Introduction
Database tables are often related to one another. For example, a blog post may have many comments or an order could be related to the user who placed it. Eloquent makes managing and working with these relationships easy, and supports a variety of common relationships:
Defining Relationships
Eloquent relationships are defined as methods on your Eloquent model
classes. Since relationships also serve as powerful query builders, defining relationships as
methods provides powerful method chaining and querying capabilities. For
example, we may chain additional query constraints on this
posts
relationship:
$user->posts()->where('active', 1)->get();
But, before diving too deep into using relationships, let's learn how to define each type of relationship supported by Eloquent.
One To One
A one-to-one relationship is a very basic type of database
relationship. For example, a User
model might be associated
with one Phone
model. To define this relationship, we will
place a phone
method on the User
model. The
phone
method should call the hasOne
method and
return its result. The hasOne
method is available to your
model via the model's Illuminate\Database\Eloquent\Model
base class:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class User extends Model
{
/**
* Get the phone associated with the user.
*/
public function phone()
{
return $this->hasOne(Phone::class);
}
}
The first argument passed to the hasOne
method is the
name of the related model class. Once the relationship is defined, we
may retrieve the related record using Eloquent's dynamic properties.
Dynamic properties allow you to access relationship methods as if they
were properties defined on the model:
$phone = User::find(1)->phone;
Eloquent determines the foreign key of the relationship based on the
parent model name. In this case, the Phone
model is
automatically assumed to have a user_id
foreign key. If you
wish to override this convention, you may pass a second argument to the
hasOne
method:
return $this->hasOne(Phone::class, 'foreign_key');
Additionally, Eloquent assumes that the foreign key should have a
value matching the primary key column of the parent. In other words,
Eloquent will look for the value of the user's id
column in
the user_id
column of the Phone
record. If you
would like the relationship to use a primary key value other than
id
or your model's $primaryKey
property, you
may pass a third argument to the hasOne
method:
return $this->hasOne(Phone::class, 'foreign_key', 'local_key');
Defining The Inverse Of The Relationship
So, we can access the Phone
model from our
User
model. Next, let's define a relationship on the
Phone
model that will let us access the user that owns the
phone. We can define the inverse of a hasOne
relationship
using the belongsTo
method:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Phone extends Model
{
/**
* Get the user that owns the phone.
*/
public function user()
{
return $this->belongsTo(User::class);
}
}
When invoking the user
method, Eloquent will attempt to
find a User
model that has an id
which matches
the user_id
column on the Phone
model.
Eloquent determines the foreign key name by examining the name of the
relationship method and suffixing the method name with _id
.
So, in this case, Eloquent assumes that the Phone
model has
a user_id
column. However, if the foreign key on the
Phone
model is not user_id
, you may pass a
custom key name as the second argument to the belongsTo
method:
/**
* Get the user that owns the phone.
*/
public function user()
{
return $this->belongsTo(User::class, 'foreign_key');
}
If the parent model does not use id
as its primary key,
or you wish to find the associated model using a different column, you
may pass a third argument to the belongsTo
method
specifying the parent table's custom key:
/**
* Get the user that owns the phone.
*/
public function user()
{
return $this->belongsTo(User::class, 'foreign_key', 'owner_key');
}
One To Many
A one-to-many relationship is used to define relationships where a single model is the parent to one or more child models. For example, a blog post may have an infinite number of comments. Like all other Eloquent relationships, one-to-many relationships are defined by defining a method on your Eloquent model:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Post extends Model
{
/**
* Get the comments for the blog post.
*/
public function comments()
{
return $this->hasMany(Comment::class);
}
}
Remember, Eloquent will automatically determine the proper foreign
key column for the Comment
model. By convention, Eloquent
will take the "snake case" name of the parent model and suffix it with
_id
. So, in this example, Eloquent will assume the foreign
key column on the Comment
model is
post_id
.
Once the relationship method has been defined, we can access the collection of related comments by
accessing the comments
property. Remember, since Eloquent
provides "dynamic relationship properties", we can access relationship
methods as if they were defined as properties on the model:
use App\Models\Post;
$comments = Post::find(1)->comments;
foreach ($comments as $comment) {
//
}
Since all relationships also serve as query builders, you may add
further constraints to the relationship query by calling the
comments
method and continuing to chain conditions onto the
query:
$comment = Post::find(1)->comments()
->where('title', 'foo')
->first();
Like the hasOne
method, you may also override the
foreign and local keys by passing additional arguments to the
hasMany
method:
return $this->hasMany(Comment::class, 'foreign_key');
return $this->hasMany(Comment::class, 'foreign_key', 'local_key');
One To Many (Inverse) / Belongs To
Now that we can access all of a post's comments, let's define a
relationship to allow a comment to access its parent post. To define the
inverse of a hasMany
relationship, define a relationship
method on the child model which calls the belongsTo
method:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Comment extends Model
{
/**
* Get the post that owns the comment.
*/
public function post()
{
return $this->belongsTo(Post::class);
}
}
Once the relationship has been defined, we can retrieve a comment's
parent post by accessing the post
"dynamic relationship
property":
use App\Models\Comment;
$comment = Comment::find(1);
return $comment->post->title;
In the example above, Eloquent will attempt to find a
Post
model that has an id
which matches the
post_id
column on the Comment
model.
Eloquent determines the default foreign key name by examining the
name of the relationship method and suffixing the method name with a
_
followed by the name of the parent model's primary key
column. So, in this example, Eloquent will assume the Post
model's foreign key on the comments
table is
post_id
.
However, if the foreign key for your relationship does not follow
these conventions, you may pass a custom foreign key name as the second
argument to the belongsTo
method:
/**
* Get the post that owns the comment.
*/
public function post()
{
return $this->belongsTo(Post::class, 'foreign_key');
}
If your parent model does not use id
as its primary key,
or you wish to find the associated model using a different column, you
may pass a third argument to the belongsTo
method
specifying your parent table's custom key:
/**
* Get the post that owns the comment.
*/
public function post()
{
return $this->belongsTo(Post::class, 'foreign_key', 'owner_key');
}
Default Models
The belongsTo
, hasOne
,
hasOneThrough
, and morphOne
relationships
allow you to define a default model that will be returned if the given
relationship is null
. This pattern is often referred to as
the Null
Object pattern and can help remove conditional checks in your code.
In the following example, the user
relation will return an
empty App\Models\User
model if no user is attached to the
Post
model:
/**
* Get the author of the post.
*/
public function user()
{
return $this->belongsTo(User::class)->withDefault();
}
To populate the default model with attributes, you may pass an array
or closure to the withDefault
method:
/**
* Get the author of the post.
*/
public function user()
{
return $this->belongsTo(User::class)->withDefault([
'name' => 'Guest Author',
]);
}
/**
* Get the author of the post.
*/
public function user()
{
return $this->belongsTo(User::class)->withDefault(function ($user, $post) {
$user->name = 'Guest Author';
});
}
Querying Belongs To Relationships
When querying for the children of a "belongs to" relationship, you
may manually build the where
clause to retrieve the
corresponding Eloquent models:
use App\Models\Post;
$posts = Post::where('user_id', $user->id)->get();
However, you may find it more convenient to use the
whereBelongsTo
method, which will automatically determine
the proper relationship and foreign key for the given model:
$posts = Post::whereBelongsTo($user)->get();
You may also provide a collection instance to the
whereBelongsTo
method. When doing so, Laravel will retrieve
models that belong to any of the parent models within the
collection:
$users = User::where('vip', true)->get();
$posts = Post::whereBelongsTo($users)->get();
By default, Laravel will determine the relationship associated with
the given model based on the class name of the model; however, you may
specify the relationship name manually by providing it as the second
argument to the whereBelongsTo
method:
$posts = Post::whereBelongsTo($user, 'author')->get();
Has One Of Many
Sometimes a model may have many related models, yet you want to
easily retrieve the "latest" or "oldest" related model of the
relationship. For example, a User
model may be related to
many Order
models, but you want to define a convenient way
to interact with the most recent order the user has placed. You may
accomplish this using the hasOne
relationship type combined
with the ofMany
methods:
/**
* Get the user's most recent order.
*/
public function latestOrder()
{
return $this->hasOne(Order::class)->latestOfMany();
}
Likewise, you may define a method to retrieve the "oldest", or first, related model of a relationship:
/**
* Get the user's oldest order.
*/
public function oldestOrder()
{
return $this->hasOne(Order::class)->oldestOfMany();
}
By default, the latestOfMany
and
oldestOfMany
methods will retrieve the latest or oldest
related model based on the model's primary key, which must be sortable.
However, sometimes you may wish to retrieve a single model from a larger
relationship using a different sorting criteria.
For example, using the ofMany
method, you may retrieve
the user's most expensive order. The ofMany
method accepts
the sortable column as its first argument and which aggregate function
(min
or max
) to apply when querying for the
related model:
/**
* Get the user's largest order.
*/
public function largestOrder()
{
return $this->hasOne(Order::class)->ofMany('price', 'max');
}
Warning!!
Because PostgreSQL does not support executing theMAX
function against UUID columns, it is not currently possible to use one-of-many relationships in combination with PostgreSQL UUID columns.
Advanced Has One Of Many Relationships
It is possible to construct more advanced "has one of many"
relationships. For example, a Product
model may have many
associated Price
models that are retained in the system
even after new pricing is published. In addition, new pricing data for
the product may be able to be published in advance to take effect at a
future date via a published_at
column.
So, in summary, we need to retrieve the latest published pricing
where the published date is not in the future. In addition, if two
prices have the same published date, we will prefer the price with the
greatest ID. To accomplish this, we must pass an array to the
ofMany
method that contains the sortable columns which
determine the latest price. In addition, a closure will be provided as
the second argument to the ofMany
method. This closure will
be responsible for adding additional publish date constraints to the
relationship query:
/**
* Get the current pricing for the product.
*/
public function currentPricing()
{
return $this->hasOne(Price::class)->ofMany([
'published_at' => 'max',
'id' => 'max',
], function ($query) {
$query->where('published_at', '<', now());
});
}
Has One Through
The "has-one-through" relationship defines a one-to-one relationship with another model. However, this relationship indicates that the declaring model can be matched with one instance of another model by proceeding through a third model.
For example, in a vehicle repair shop application, each
Mechanic
model may be associated with one Car
model, and each Car
model may be associated with one
Owner
model. While the mechanic and the owner have no
direct relationship within the database, the mechanic can access the
owner through the Car
model. Let's look at the
tables necessary to define this relationship:
mechanics
id - integer
name - string
cars
id - integer
model - string
mechanic_id - integer
owners
id - integer
name - string
car_id - integer
Now that we have examined the table structure for the relationship,
let's define the relationship on the Mechanic
model:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Mechanic extends Model
{
/**
* Get the car's owner.
*/
public function carOwner()
{
return $this->hasOneThrough(Owner::class, Car::class);
}
}
The first argument passed to the hasOneThrough
method is
the name of the final model we wish to access, while the second argument
is the name of the intermediate model.
Or, if the relevant relationships have already been defined on all of
the models involved in the relationship, you may fluently define a
"has-one-through" relationship by invoking the through
method and supplying the names of those relationships. For example, if
the Mechanic
model has a cars
relationship and
the Car
model has an owner
relationship, you
may define a "has-one-through" relationship connecting the mechanic and
the owner like so:
// String based syntax...
return $this->through('cars')->has('owner');
// Dynamic syntax...
return $this->throughCars()->hasOwner();
Key Conventions
Typical Eloquent foreign key conventions will be used when performing
the relationship's queries. If you would like to customize the keys of
the relationship, you may pass them as the third and fourth arguments to
the hasOneThrough
method. The third argument is the name of
the foreign key on the intermediate model. The fourth argument is the
name of the foreign key on the final model. The fifth argument is the
local key, while the sixth argument is the local key of the intermediate
model:
class Mechanic extends Model
{
/**
* Get the car's owner.
*/
public function carOwner()
{
return $this->hasOneThrough(
Owner::class,
Car::class,
'mechanic_id', // Foreign key on the cars table...
'car_id', // Foreign key on the owners table...
'id', // Local key on the mechanics table...
'id' // Local key on the cars table...
);
}
}
Or, as discussed earlier, if the relevant relationships have already
been defined on all of the models involved in the relationship, you may
fluently define a "has-one-through" relationship by invoking the
through
method and supplying the names of those
relationships. This approach offers the advantage of reusing the key
conventions already defined on the existing relationships:
// String based syntax...
return $this->through('cars')->has('owner');
// Dynamic syntax...
return $this->throughCars()->hasOwner();
Has Many Through
The "has-many-through" relationship provides a convenient way to
access distant relations via an intermediate relation. For example,
let's assume we are building a deployment platform like Laravel Vapor. A
Project
model might access many Deployment
models through an intermediate Environment
model. Using
this example, you could easily gather all deployments for a given
project. Let's look at the tables required to define this
relationship:
projects
id - integer
name - string
environments
id - integer
project_id - integer
name - string
deployments
id - integer
environment_id - integer
commit_hash - string
Now that we have examined the table structure for the relationship,
let's define the relationship on the Project
model:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Project extends Model
{
/**
* Get all of the deployments for the project.
*/
public function deployments()
{
return $this->hasManyThrough(Deployment::class, Environment::class);
}
}
The first argument passed to the hasManyThrough
method
is the name of the final model we wish to access, while the second
argument is the name of the intermediate model.
Or, if the relevant relationships have already been defined on all of
the models involved in the relationship, you may fluently define a
"has-many-through" relationship by invoking the through
method and supplying the names of those relationships. For example, if
the Project
model has a environments
relationship and the Environment
model has a
deployments
relationship, you may define a
"has-many-through" relationship connecting the project and the
deployments like so:
// String based syntax...
return $this->through('environments')->has('deployments');
// Dynamic syntax...
return $this->throughEnvironments()->hasDeployments();
Though the Deployment
model's table does not contain a
project_id
column, the hasManyThrough
relation
provides access to a project's deployments via
$project->deployments
. To retrieve these models,
Eloquent inspects the project_id
column on the intermediate
Environment
model's table. After finding the relevant
environment IDs, they are used to query the Deployment
model's table.
Key Conventions
Typical Eloquent foreign key conventions will be used when performing
the relationship's queries. If you would like to customize the keys of
the relationship, you may pass them as the third and fourth arguments to
the hasManyThrough
method. The third argument is the name
of the foreign key on the intermediate model. The fourth argument is the
name of the foreign key on the final model. The fifth argument is the
local key, while the sixth argument is the local key of the intermediate
model:
class Project extends Model
{
public function deployments()
{
return $this->hasManyThrough(
Deployment::class,
Environment::class,
'project_id', // Foreign key on the environments table...
'environment_id', // Foreign key on the deployments table...
'id', // Local key on the projects table...
'id' // Local key on the environments table...
);
}
}
Or, as discussed earlier, if the relevant relationships have already
been defined on all of the models involved in the relationship, you may
fluently define a "has-many-through" relationship by invoking the
through
method and supplying the names of those
relationships. This approach offers the advantage of reusing the key
conventions already defined on the existing relationships:
// String based syntax...
return $this->through('environments')->has('deployments');
// Dynamic syntax...
return $this->throughEnvironments()->hasDeployments();
Many To Many Relationships
Many-to-many relations are slightly more complicated than
hasOne
and hasMany
relationships. An example
of a many-to-many relationship is a user that has many roles and those
roles are also shared by other users in the application. For example, a
user may be assigned the role of "Author" and "Editor"; however, those
roles may also be assigned to other users as well. So, a user has many
roles and a role has many users.
Table Structure
To define this relationship, three database tables are needed:
users
, roles
, and role_user
. The
role_user
table is derived from the alphabetical order of
the related model names and contains user_id
and
role_id
columns. This table is used as an intermediate
table linking the users and roles.
Remember, since a role can belong to many users, we cannot simply
place a user_id
column on the roles
table.
This would mean that a role could only belong to a single user. In order
to provide support for roles being assigned to multiple users, the
role_user
table is needed. We can summarize the
relationship's table structure like so:
users
id - integer
name - string
roles
id - integer
name - string
role_user
user_id - integer
role_id - integer
Model Structure
Many-to-many relationships are defined by writing a method that
returns the result of the belongsToMany
method. The
belongsToMany
method is provided by the
Illuminate\Database\Eloquent\Model
base class that is used
by all of your application's Eloquent models. For example, let's define
a roles
method on our User
model. The first
argument passed to this method is the name of the related model
class:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class User extends Model
{
/**
* The roles that belong to the user.
*/
public function roles()
{
return $this->belongsToMany(Role::class);
}
}
Once the relationship is defined, you may access the user's roles
using the roles
dynamic relationship property:
use App\Models\User;
$user = User::find(1);
foreach ($user->roles as $role) {
//
}
Since all relationships also serve as query builders, you may add
further constraints to the relationship query by calling the
roles
method and continuing to chain conditions onto the
query:
$roles = User::find(1)->roles()->orderBy('name')->get();
To determine the table name of the relationship's intermediate table,
Eloquent will join the two related model names in alphabetical order.
However, you are free to override this convention. You may do so by
passing a second argument to the belongsToMany
method:
return $this->belongsToMany(Role::class, 'role_user');
In addition to customizing the name of the intermediate table, you
may also customize the column names of the keys on the table by passing
additional arguments to the belongsToMany
method. The third
argument is the foreign key name of the model on which you are defining
the relationship, while the fourth argument is the foreign key name of
the model that you are joining to:
return $this->belongsToMany(Role::class, 'role_user', 'user_id', 'role_id');
Defining The Inverse Of The Relationship
To define the "inverse" of a many-to-many relationship, you should
define a method on the related model which also returns the result of
the belongsToMany
method. To complete our user / role
example, let's define the users
method on the
Role
model:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Role extends Model
{
/**
* The users that belong to the role.
*/
public function users()
{
return $this->belongsToMany(User::class);
}
}
As you can see, the relationship is defined exactly the same as its
User
model counterpart with the exception of referencing
the App\Models\User
model. Since we're reusing the
belongsToMany
method, all of the usual table and key
customization options are available when defining the "inverse" of
many-to-many relationships.
Retrieving Intermediate Table Columns
As you have already learned, working with many-to-many relations
requires the presence of an intermediate table. Eloquent provides some
very helpful ways of interacting with this table. For example, let's
assume our User
model has many Role
models
that it is related to. After accessing this relationship, we may access
the intermediate table using the pivot
attribute on the
models:
use App\Models\User;
$user = User::find(1);
foreach ($user->roles as $role) {
echo $role->pivot->created_at;
}
Notice that each Role
model we retrieve is automatically
assigned a pivot
attribute. This attribute contains a model
representing the intermediate table.
By default, only the model keys will be present on the
pivot
model. If your intermediate table contains extra
attributes, you must specify them when defining the relationship:
return $this->belongsToMany(Role::class)->withPivot('active', 'created_by');
If you would like your intermediate table to have
created_at
and updated_at
timestamps that are
automatically maintained by Eloquent, call the
withTimestamps
method when defining the relationship:
return $this->belongsToMany(Role::class)->withTimestamps();
Warning!!
Intermediate tables that utilize Eloquent's automatically maintained timestamps are required to have bothcreated_at
andupdated_at
timestamp columns.
Customizing The pivot
Attribute Name
As noted previously, attributes from the intermediate table may be
accessed on models via the pivot
attribute. However, you
are free to customize the name of this attribute to better reflect its
purpose within your application.
For example, if your application contains users that may subscribe to
podcasts, you likely have a many-to-many relationship between users and
podcasts. If this is the case, you may wish to rename your intermediate
table attribute to subscription
instead of
pivot
. This can be done using the as
method
when defining the relationship:
return $this->belongsToMany(Podcast::class)
->as('subscription')
->withTimestamps();
Once the custom intermediate table attribute has been specified, you may access the intermediate table data using the customized name:
$users = User::with('podcasts')->get();
foreach ($users->flatMap->podcasts as $podcast) {
echo $podcast->subscription->created_at;
}
Filtering Queries Via Intermediate Table Columns
You can also filter the results returned by
belongsToMany
relationship queries using the
wherePivot
, wherePivotIn
,
wherePivotNotIn
, wherePivotBetween
,
wherePivotNotBetween
, wherePivotNull
, and
wherePivotNotNull
methods when defining the
relationship:
return $this->belongsToMany(Role::class)
->wherePivot('approved', 1);
return $this->belongsToMany(Role::class)
->wherePivotIn('priority', [1, 2]);
return $this->belongsToMany(Role::class)
->wherePivotNotIn('priority', [1, 2]);
return $this->belongsToMany(Podcast::class)
->as('subscriptions')
->wherePivotBetween('created_at', ['2020-01-01 00:00:00', '2020-12-31 00:00:00']);
return $this->belongsToMany(Podcast::class)
->as('subscriptions')
->wherePivotNotBetween('created_at', ['2020-01-01 00:00:00', '2020-12-31 00:00:00']);
return $this->belongsToMany(Podcast::class)
->as('subscriptions')
->wherePivotNull('expired_at');
return $this->belongsToMany(Podcast::class)
->as('subscriptions')
->wherePivotNotNull('expired_at');
Ordering Queries Via Intermediate Table Columns
You can order the results returned by belongsToMany
relationship queries using the orderByPivot
method. In the
following example, we will retrieve all of the latest badges for the
user:
return $this->belongsToMany(Badge::class)
->where('rank', 'gold')
->orderByPivot('created_at', 'desc');
Defining Custom Intermediate Table Models
If you would like to define a custom model to represent the
intermediate table of your many-to-many relationship, you may call the
using
method when defining the relationship. Custom pivot
models give you the opportunity to define additional behavior on the
pivot model, such as methods and casts.
Custom many-to-many pivot models should extend the
Illuminate\Database\Eloquent\Relations\Pivot
class while
custom polymorphic many-to-many pivot models should extend the
Illuminate\Database\Eloquent\Relations\MorphPivot
class.
For example, we may define a Role
model which uses a custom
RoleUser
pivot model:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Role extends Model
{
/**
* The users that belong to the role.
*/
public function users()
{
return $this->belongsToMany(User::class)->using(RoleUser::class);
}
}
When defining the RoleUser
model, you should extend the
Illuminate\Database\Eloquent\Relations\Pivot
class:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Relations\Pivot;
class RoleUser extends Pivot
{
//
}
Warning!!
Pivot models may not use theSoftDeletes
trait. If you need to soft delete pivot records consider converting your pivot model to an actual Eloquent model.
Custom Pivot Models And Incrementing IDs
If you have defined a many-to-many relationship that uses a custom
pivot model, and that pivot model has an auto-incrementing primary key,
you should ensure your custom pivot model class defines an
incrementing
property that is set to true
.
/**
* Indicates if the IDs are auto-incrementing.
*
* @var bool
*/
public $incrementing = true;
Polymorphic Relationships
A polymorphic relationship allows the child model to belong to more
than one type of model using a single association. For example, imagine
you are building an application that allows users to share blog posts
and videos. In such an application, a Comment
model might
belong to both the Post
and Video
models.
One To One (Polymorphic)
Table Structure
A one-to-one polymorphic relation is similar to a typical one-to-one
relation; however, the child model can belong to more than one type of
model using a single association. For example, a blog Post
and a User
may share a polymorphic relation to an
Image
model. Using a one-to-one polymorphic relation allows
you to have a single table of unique images that may be associated with
posts and users. First, let's examine the table structure:
posts
id - integer
name - string
users
id - integer
name - string
images
id - integer
url - string
imageable_id - integer
imageable_type - string
Note the imageable_id
and imageable_type
columns on the images
table. The imageable_id
column will contain the ID value of the post or user, while the
imageable_type
column will contain the class name of the
parent model. The imageable_type
column is used by Eloquent
to determine which "type" of parent model to return when accessing the
imageable
relation. In this case, the column would contain
either App\Models\Post
or App\Models\User
.
Model Structure
Next, let's examine the model definitions needed to build this relationship:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Image extends Model
{
/**
* Get the parent imageable model (user or post).
*/
public function imageable()
{
return $this->morphTo();
}
}
class Post extends Model
{
/**
* Get the post's image.
*/
public function image()
{
return $this->morphOne(Image::class, 'imageable');
}
}
class User extends Model
{
/**
* Get the user's image.
*/
public function image()
{
return $this->morphOne(Image::class, 'imageable');
}
}
Retrieving The Relationship
Once your database table and models are defined, you may access the
relationships via your models. For example, to retrieve the image for a
post, we can access the image
dynamic relationship
property:
use App\Models\Post;
$post = Post::find(1);
$image = $post->image;
You may retrieve the parent of the polymorphic model by accessing the
name of the method that performs the call to morphTo
. In
this case, that is the imageable
method on the
Image
model. So, we will access that method as a dynamic
relationship property:
use App\Models\Image;
$image = Image::find(1);
$imageable = $image->imageable;
The imageable
relation on the Image
model
will return either a Post
or User
instance,
depending on which type of model owns the image.
Key Conventions
If necessary, you may specify the name of the "id" and "type" columns
utilized by your polymorphic child model. If you do so, ensure that you
always pass the name of the relationship as the first argument to the
morphTo
method. Typically, this value should match the
method name, so you may use PHP's __FUNCTION__
constant:
/**
* Get the model that the image belongs to.
*/
public function imageable()
{
return $this->morphTo(__FUNCTION__, 'imageable_type', 'imageable_id');
}
One To Many (Polymorphic)
Table Structure
A one-to-many polymorphic relation is similar to a typical
one-to-many relation; however, the child model can belong to more than
one type of model using a single association. For example, imagine users
of your application can "comment" on posts and videos. Using polymorphic
relationships, you may use a single comments
table to
contain comments for both posts and videos. First, let's examine the
table structure required to build this relationship:
posts
id - integer
title - string
body - text
videos
id - integer
title - string
url - string
comments
id - integer
body - text
commentable_id - integer
commentable_type - string
Model Structure
Next, let's examine the model definitions needed to build this relationship:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Comment extends Model
{
/**
* Get the parent commentable model (post or video).
*/
public function commentable()
{
return $this->morphTo();
}
}
class Post extends Model
{
/**
* Get all of the post's comments.
*/
public function comments()
{
return $this->morphMany(Comment::class, 'commentable');
}
}
class Video extends Model
{
/**
* Get all of the video's comments.
*/
public function comments()
{
return $this->morphMany(Comment::class, 'commentable');
}
}
Retrieving The Relationship
Once your database table and models are defined, you may access the
relationships via your model's dynamic relationship properties. For
example, to access all of the comments for a post, we can use the
comments
dynamic property:
use App\Models\Post;
$post = Post::find(1);
foreach ($post->comments as $comment) {
//
}
You may also retrieve the parent of a polymorphic child model by
accessing the name of the method that performs the call to
morphTo
. In this case, that is the commentable
method on the Comment
model. So, we will access that method
as a dynamic relationship property in order to access the comment's
parent model:
use App\Models\Comment;
$comment = Comment::find(1);
$commentable = $comment->commentable;
The commentable
relation on the Comment
model will return either a Post
or Video
instance, depending on which type of model is the comment's parent.
One Of Many (Polymorphic)
Sometimes a model may have many related models, yet you want to
easily retrieve the "latest" or "oldest" related model of the
relationship. For example, a User
model may be related to
many Image
models, but you want to define a convenient way
to interact with the most recent image the user has uploaded. You may
accomplish this using the morphOne
relationship type
combined with the ofMany
methods:
/**
* Get the user's most recent image.
*/
public function latestImage()
{
return $this->morphOne(Image::class, 'imageable')->latestOfMany();
}
Likewise, you may define a method to retrieve the "oldest", or first, related model of a relationship:
/**
* Get the user's oldest image.
*/
public function oldestImage()
{
return $this->morphOne(Image::class, 'imageable')->oldestOfMany();
}
By default, the latestOfMany
and
oldestOfMany
methods will retrieve the latest or oldest
related model based on the model's primary key, which must be sortable.
However, sometimes you may wish to retrieve a single model from a larger
relationship using a different sorting criteria.
For example, using the ofMany
method, you may retrieve
the user's most "liked" image. The ofMany
method accepts
the sortable column as its first argument and which aggregate function
(min
or max
) to apply when querying for the
related model:
/**
* Get the user's most popular image.
*/
public function bestImage()
{
return $this->morphOne(Image::class, 'imageable')->ofMany('likes', 'max');
}
Note:
It is possible to construct more advanced "one of many" relationships. For more information, please consult the has one of many documentation.
Many To Many (Polymorphic)
Table Structure
Many-to-many polymorphic relations are slightly more complicated than
"morph one" and "morph many" relationships. For example, a
Post
model and Video
model could share a
polymorphic relation to a Tag
model. Using a many-to-many
polymorphic relation in this situation would allow your application to
have a single table of unique tags that may be associated with posts or
videos. First, let's examine the table structure required to build this
relationship:
posts
id - integer
name - string
videos
id - integer
name - string
tags
id - integer
name - string
taggables
tag_id - integer
taggable_id - integer
taggable_type - string
Note:
Before diving into polymorphic many-to-many relationships, you may benefit from reading the documentation on typical many-to-many relationships.
Model Structure
Next, we're ready to define the relationships on the models. The
Post
and Video
models will both contain a
tags
method that calls the morphToMany
method
provided by the base Eloquent model class.
The morphToMany
method accepts the name of the related
model as well as the "relationship name". Based on the name we assigned
to our intermediate table name and the keys it contains, we will refer
to the relationship as "taggable":
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Post extends Model
{
/**
* Get all of the tags for the post.
*/
public function tags()
{
return $this->morphToMany(Tag::class, 'taggable');
}
}
Defining The Inverse Of The Relationship
Next, on the Tag
model, you should define a method for
each of its possible parent models. So, in this example, we will define
a posts
method and a videos
method. Both of
these methods should return the result of the morphedByMany
method.
The morphedByMany
method accepts the name of the related
model as well as the "relationship name". Based on the name we assigned
to our intermediate table name and the keys it contains, we will refer
to the relationship as "taggable":
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Tag extends Model
{
/**
* Get all of the posts that are assigned this tag.
*/
public function posts()
{
return $this->morphedByMany(Post::class, 'taggable');
}
/**
* Get all of the videos that are assigned this tag.
*/
public function videos()
{
return $this->morphedByMany(Video::class, 'taggable');
}
}
Retrieving The Relationship
Once your database table and models are defined, you may access the
relationships via your models. For example, to access all of the tags
for a post, you may use the tags
dynamic relationship
property:
use App\Models\Post;
$post = Post::find(1);
foreach ($post->tags as $tag) {
//
}
You may retrieve the parent of a polymorphic relation from the
polymorphic child model by accessing the name of the method that
performs the call to morphedByMany
. In this case, that is
the posts
or videos
methods on the
Tag
model:
use App\Models\Tag;
$tag = Tag::find(1);
foreach ($tag->posts as $post) {
//
}
foreach ($tag->videos as $video) {
//
}
Custom Polymorphic Types
By default, Laravel will use the fully qualified class name to store
the "type" of the related model. For instance, given the one-to-many
relationship example above where a Comment
model may belong
to a Post
or a Video
model, the default
commentable_type
would be either
App\Models\Post
or App\Models\Video
,
respectively. However, you may wish to decouple these values from your
application's internal structure.
For example, instead of using the model names as the "type", we may
use simple strings such as post
and video
. By
doing so, the polymorphic "type" column values in our database will
remain valid even if the models are renamed:
use Illuminate\Database\Eloquent\Relations\Relation;
Relation::enforceMorphMap([
'post' => 'App\Models\Post',
'video' => 'App\Models\Video',
]);
You may call the enforceMorphMap
method in the
boot
method of your
App\Providers\AppServiceProvider
class or create a separate
service provider if you wish.
You may determine the morph alias of a given model at runtime using
the model's getMorphClass
method. Conversely, you may
determine the fully-qualified class name associated with a morph alias
using the Relation::getMorphedModel
method:
use Illuminate\Database\Eloquent\Relations\Relation;
$alias = $post->getMorphClass();
$class = Relation::getMorphedModel($alias);
Warning!!
When adding a "morph map" to your existing application, every morphable*_type
column value in your database that still contains a fully-qualified class will need to be converted to its "map" name.
Dynamic Relationships
You may use the resolveRelationUsing
method to define
relations between Eloquent models at runtime. While not typically
recommended for normal application development, this may occasionally be
useful when developing Laravel packages.
The resolveRelationUsing
method accepts the desired
relationship name as its first argument. The second argument passed to
the method should be a closure that accepts the model instance and
returns a valid Eloquent relationship definition. Typically, you should
configure dynamic relationships within the boot method of a service provider:
use App\Models\Order;
use App\Models\Customer;
Order::resolveRelationUsing('customer', function ($orderModel) {
return $orderModel->belongsTo(Customer::class, 'customer_id');
});
Warning!!
When defining dynamic relationships, always provide explicit key name arguments to the Eloquent relationship methods.
Querying Relations
Since all Eloquent relationships are defined via methods, you may call those methods to obtain an instance of the relationship without actually executing a query to load the related models. In addition, all types of Eloquent relationships also serve as query builders, allowing you to continue to chain constraints onto the relationship query before finally executing the SQL query against your database.
For example, imagine a blog application in which a User
model has many associated Post
models:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class User extends Model
{
/**
* Get all of the posts for the user.
*/
public function posts()
{
return $this->hasMany(Post::class);
}
}
You may query the posts
relationship and add additional
constraints to the relationship like so:
use App\Models\User;
$user = User::find(1);
$user->posts()->where('active', 1)->get();
You are able to use any of the Laravel query builder's methods on the relationship, so be sure to explore the query builder documentation to learn about all of the methods that are available to you.
Chaining orWhere
Clauses After Relationships
As demonstrated in the example above, you are free to add additional
constraints to relationships when querying them. However, use caution
when chaining orWhere
clauses onto a relationship, as the
orWhere
clauses will be logically grouped at the same level
as the relationship constraint:
$user->posts()
->where('active', 1)
->orWhere('votes', '>=', 100)
->get();
The example above will generate the following SQL. As you can see,
the or
clause instructs the query to return any
user with greater than 100 votes. The query is no longer constrained to
a specific user:
select *
from posts
where user_id = ? and active = 1 or votes >= 100
In most situations, you should use logical groups to group the conditional checks between parentheses:
use Illuminate\Database\Eloquent\Builder;
$user->posts()
->where(function (Builder $query) {
return $query->where('active', 1)
->orWhere('votes', '>=', 100);
})
->get();
The example above will produce the following SQL. Note that the logical grouping has properly grouped the constraints and the query remains constrained to a specific user:
select *
from posts
where user_id = ? and (active = 1 or votes >= 100)
Relationship Methods Vs. Dynamic Properties
If you do not need to add additional constraints to an Eloquent
relationship query, you may access the relationship as if it were a
property. For example, continuing to use our User
and
Post
example models, we may access all of a user's posts
like so:
use App\Models\User;
$user = User::find(1);
foreach ($user->posts as $post) {
//
}
Dynamic relationship properties perform "lazy loading", meaning they will only load their relationship data when you actually access them. Because of this, developers often use eager loading to pre-load relationships they know will be accessed after loading the model. Eager loading provides a significant reduction in SQL queries that must be executed to load a model's relations.
Querying Relationship Existence
When retrieving model records, you may wish to limit your results
based on the existence of a relationship. For example, imagine you want
to retrieve all blog posts that have at least one comment. To do so, you
may pass the name of the relationship to the has
and
orHas
methods:
use App\Models\Post;
// Retrieve all posts that have at least one comment...
$posts = Post::has('comments')->get();
You may also specify an operator and count value to further customize the query:
// Retrieve all posts that have three or more comments...
$posts = Post::has('comments', '>=', 3)->get();
Nested has
statements may be constructed using "dot"
notation. For example, you may retrieve all posts that have at least one
comment that has at least one image:
// Retrieve posts that have at least one comment with images...
$posts = Post::has('comments.images')->get();
If you need even more power, you may use the whereHas
and orWhereHas
methods to define additional query
constraints on your has
queries, such as inspecting the
content of a comment:
use Illuminate\Database\Eloquent\Builder;
// Retrieve posts with at least one comment containing words like code%...
$posts = Post::whereHas('comments', function (Builder $query) {
$query->where('content', 'like', 'code%');
})->get();
// Retrieve posts with at least ten comments containing words like code%...
$posts = Post::whereHas('comments', function (Builder $query) {
$query->where('content', 'like', 'code%');
}, '>=', 10)->get();
Warning!!
Eloquent does not currently support querying for relationship existence across databases. The relationships must exist within the same database.
Inline Relationship Existence Queries
If you would like to query for a relationship's existence with a
single, simple where condition attached to the relationship query, you
may find it more convenient to use the whereRelation
,
orWhereRelation
, whereMorphRelation
, and
orWhereMorphRelation
methods. For example, we may query for
all posts that have unapproved comments:
use App\Models\Post;
$posts = Post::whereRelation('comments', 'is_approved', false)->get();
Of course, like calls to the query builder's where
method, you may also specify an operator:
$posts = Post::whereRelation(
'comments', 'created_at', '>=', now()->subHour()
)->get();
Querying Relationship Absence
When retrieving model records, you may wish to limit your results
based on the absence of a relationship. For example, imagine you want to
retrieve all blog posts that don't have any comments.
To do so, you may pass the name of the relationship to the
doesntHave
and orDoesntHave
methods:
use App\Models\Post;
$posts = Post::doesntHave('comments')->get();
If you need even more power, you may use the
whereDoesntHave
and orWhereDoesntHave
methods
to add additional query constraints to your doesntHave
queries, such as inspecting the content of a comment:
use Illuminate\Database\Eloquent\Builder;
$posts = Post::whereDoesntHave('comments', function (Builder $query) {
$query->where('content', 'like', 'code%');
})->get();
You may use "dot" notation to execute a query against a nested relationship. For example, the following query will retrieve all posts that do not have comments; however, posts that have comments from authors that are not banned will be included in the results:
use Illuminate\Database\Eloquent\Builder;
$posts = Post::whereDoesntHave('comments.author', function (Builder $query) {
$query->where('banned', 0);
})->get();
Querying Morph To Relationships
To query the existence of "morph to" relationships, you may use the
whereHasMorph
and whereDoesntHaveMorph
methods. These methods accept the name of the relationship as their
first argument. Next, the methods accept the names of the related models
that you wish to include in the query. Finally, you may provide a
closure which customizes the relationship query:
use App\Models\Comment;
use App\Models\Post;
use App\Models\Video;
use Illuminate\Database\Eloquent\Builder;
// Retrieve comments associated to posts or videos with a title like code%...
$comments = Comment::whereHasMorph(
'commentable',
[Post::class, Video::class],
function (Builder $query) {
$query->where('title', 'like', 'code%');
}
)->get();
// Retrieve comments associated to posts with a title not like code%...
$comments = Comment::whereDoesntHaveMorph(
'commentable',
Post::class,
function (Builder $query) {
$query->where('title', 'like', 'code%');
}
)->get();
You may occasionally need to add query constraints based on the
"type" of the related polymorphic model. The closure passed to the
whereHasMorph
method may receive a $type
value
as its second argument. This argument allows you to inspect the "type"
of the query that is being built:
use Illuminate\Database\Eloquent\Builder;
$comments = Comment::whereHasMorph(
'commentable',
[Post::class, Video::class],
function (Builder $query, $type) {
$column = $type === Post::class ? 'content' : 'title';
$query->where($column, 'like', 'code%');
}
)->get();
Querying All Related Models
Instead of passing an array of possible polymorphic models, you may
provide *
as a wildcard value. This will instruct Laravel
to retrieve all of the possible polymorphic types from the database.
Laravel will execute an additional query in order to perform this
operation:
use Illuminate\Database\Eloquent\Builder;
$comments = Comment::whereHasMorph('commentable', '*', function (Builder $query) {
$query->where('title', 'like', 'foo%');
})->get();
Aggregating Related Models
Counting Related Models
Sometimes you may want to count the number of related models for a
given relationship without actually loading the models. To accomplish
this, you may use the withCount
method. The
withCount
method will place a {relation}_count
attribute on the resulting models:
use App\Models\Post;
$posts = Post::withCount('comments')->get();
foreach ($posts as $post) {
echo $post->comments_count;
}
By passing an array to the withCount
method, you may add
the "counts" for multiple relations as well as add additional
constraints to the queries:
use Illuminate\Database\Eloquent\Builder;
$posts = Post::withCount(['votes', 'comments' => function (Builder $query) {
$query->where('content', 'like', 'code%');
}])->get();
echo $posts[0]->votes_count;
echo $posts[0]->comments_count;
You may also alias the relationship count result, allowing multiple counts on the same relationship:
use Illuminate\Database\Eloquent\Builder;
$posts = Post::withCount([
'comments',
'comments as pending_comments_count' => function (Builder $query) {
$query->where('approved', false);
},
])->get();
echo $posts[0]->comments_count;
echo $posts[0]->pending_comments_count;
Deferred Count Loading
Using the loadCount
method, you may load a relationship
count after the parent model has already been retrieved:
$book = Book::first();
$book->loadCount('genres');
If you need to set additional query constraints on the count query, you may pass an array keyed by the relationships you wish to count. The array values should be closures which receive the query builder instance:
$book->loadCount(['reviews' => function ($query) {
$query->where('rating', 5);
}])
Relationship Counting & Custom Select Statements
If you're combining withCount
with a select
statement, ensure that you call withCount
after the
select
method:
$posts = Post::select(['title', 'body'])
->withCount('comments')
->get();
Other Aggregate Functions
In addition to the withCount
method, Eloquent provides
withMin
, withMax
, withAvg
,
withSum
, and withExists
methods. These methods
will place a {relation}_{function}_{column}
attribute on
your resulting models:
use App\Models\Post;
$posts = Post::withSum('comments', 'votes')->get();
foreach ($posts as $post) {
echo $post->comments_sum_votes;
}
If you wish to access the result of the aggregate function using another name, you may specify your own alias:
$posts = Post::withSum('comments as total_comments', 'votes')->get();
foreach ($posts as $post) {
echo $post->total_comments;
}
Like the loadCount
method, deferred versions of these
methods are also available. These additional aggregate operations may be
performed on Eloquent models that have already been retrieved:
$post = Post::first();
$post->loadSum('comments', 'votes');
If you're combining these aggregate methods with a
select
statement, ensure that you call the aggregate
methods after the select
method:
$posts = Post::select(['title', 'body'])
->withExists('comments')
->get();
Counting Related Models On Morph To Relationships
If you would like to eager load a "morph to" relationship, as well as
related model counts for the various entities that may be returned by
that relationship, you may utilize the with
method in
combination with the morphTo
relationship's
morphWithCount
method.
In this example, let's assume that Photo
and
Post
models may create ActivityFeed
models. We
will assume the ActivityFeed
model defines a "morph to"
relationship named parentable
that allows us to retrieve
the parent Photo
or Post
model for a given
ActivityFeed
instance. Additionally, let's assume that
Photo
models "have many" Tag
models and
Post
models "have many" Comment
models.
Now, let's imagine we want to retrieve ActivityFeed
instances and eager load the parentable
parent models for
each ActivityFeed
instance. In addition, we want to
retrieve the number of tags that are associated with each parent photo
and the number of comments that are associated with each parent
post:
use Illuminate\Database\Eloquent\Relations\MorphTo;
$activities = ActivityFeed::with([
'parentable' => function (MorphTo $morphTo) {
$morphTo->morphWithCount([
Photo::class => ['tags'],
Post::class => ['comments'],
]);
}])->get();
Deferred Count Loading
Let's assume we have already retrieved a set of
ActivityFeed
models and now we would like to load the
nested relationship counts for the various parentable
models associated with the activity feeds. You may use the
loadMorphCount
method to accomplish this:
$activities = ActivityFeed::with('parentable')->get();
$activities->loadMorphCount('parentable', [
Photo::class => ['tags'],
Post::class => ['comments'],
]);
Eager Loading
When accessing Eloquent relationships as properties, the related
models are "lazy loaded". This means the relationship data is not
actually loaded until you first access the property. However, Eloquent
can "eager load" relationships at the time you query the parent model.
Eager loading alleviates the "N + 1" query problem. To illustrate the N
+ 1 query problem, consider a Book
model that "belongs to"
to an Author
model:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Book extends Model
{
/**
* Get the author that wrote the book.
*/
public function author()
{
return $this->belongsTo(Author::class);
}
}
Now, let's retrieve all books and their authors:
use App\Models\Book;
$books = Book::all();
foreach ($books as $book) {
echo $book->author->name;
}
This loop will execute one query to retrieve all of the books within the database table, then another query for each book in order to retrieve the book's author. So, if we have 25 books, the code above would run 26 queries: one for the original book, and 25 additional queries to retrieve the author of each book.
Thankfully, we can use eager loading to reduce this operation to just
two queries. When building a query, you may specify which relationships
should be eager loaded using the with
method:
$books = Book::with('author')->get();
foreach ($books as $book) {
echo $book->author->name;
}
For this operation, only two queries will be executed - one query to retrieve all of the books and one query to retrieve all of the authors for all of the books:
select * from books
select * from authors where id in (1, 2, 3, 4, 5, ...)
Eager Loading Multiple Relationships
Sometimes you may need to eager load several different relationships.
To do so, just pass an array of relationships to the with
method:
$books = Book::with(['author', 'publisher'])->get();
Nested Eager Loading
To eager load a relationship's relationships, you may use "dot" syntax. For example, let's eager load all of the book's authors and all of the author's personal contacts:
$books = Book::with('author.contacts')->get();
Alternatively, you may specify nested eager loaded relationships by
providing a nested array to the with
method, which can be
convenient when eager loading multiple nested relationships:
$books = Book::with([
'author' => [
'contacts',
'publisher',
],
])->get();
Nested Eager Loading morphTo
Relationships
If you would like to eager load a morphTo
relationship,
as well as nested relationships on the various entities that may be
returned by that relationship, you may use the with
method
in combination with the morphTo
relationship's
morphWith
method. To help illustrate this method, let's
consider the following model:
<?php
use Illuminate\Database\Eloquent\Model;
class ActivityFeed extends Model
{
/**
* Get the parent of the activity feed record.
*/
public function parentable()
{
return $this->morphTo();
}
}
In this example, let's assume Event
, Photo
,
and Post
models may create ActivityFeed
models. Additionally, let's assume that Event
models belong
to a Calendar
model, Photo
models are
associated with Tag
models, and Post
models
belong to an Author
model.
Using these model definitions and relationships, we may retrieve
ActivityFeed
model instances and eager load all
parentable
models and their respective nested
relationships:
use Illuminate\Database\Eloquent\Relations\MorphTo;
$activities = ActivityFeed::query()
->with(['parentable' => function (MorphTo $morphTo) {
$morphTo->morphWith([
Event::class => ['calendar'],
Photo::class => ['tags'],
Post::class => ['author'],
]);
}])->get();
Eager Loading Specific Columns
You may not always need every column from the relationships you are retrieving. For this reason, Eloquent allows you to specify which columns of the relationship you would like to retrieve:
$books = Book::with('author:id,name,book_id')->get();
Warning!!
When using this feature, you should always include theid
column and any relevant foreign key columns in the list of columns you wish to retrieve.
Eager Loading By Default
Sometimes you might want to always load some relationships when
retrieving a model. To accomplish this, you may define a
$with
property on the model:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Book extends Model
{
/**
* The relationships that should always be loaded.
*
* @var array
*/
protected $with = ['author'];
/**
* Get the author that wrote the book.
*/
public function author()
{
return $this->belongsTo(Author::class);
}
/**
* Get the genre of the book.
*/
public function genre()
{
return $this->belongsTo(Genre::class);
}
}
If you would like to remove an item from the $with
property for a single query, you may use the without
method:
$books = Book::without('author')->get();
If you would like to override all items within the $with
property for a single query, you may use the withOnly
method:
$books = Book::withOnly('genre')->get();
Constraining Eager Loads
Sometimes you may wish to eager load a relationship but also specify
additional query conditions for the eager loading query. You can
accomplish this by passing an array of relationships to the
with
method where the array key is a relationship name and
the array value is a closure that adds additional constraints to the
eager loading query:
use App\Models\User;
$users = User::with(['posts' => function ($query) {
$query->where('title', 'like', '%code%');
}])->get();
In this example, Eloquent will only eager load posts where the post's
title
column contains the word code
. You may
call other query builder methods to further
customize the eager loading operation:
$users = User::with(['posts' => function ($query) {
$query->orderBy('created_at', 'desc');
}])->get();
Warning!!
Thelimit
andtake
query builder methods may not be used when constraining eager loads.
Constraining Eager Loading Of morphTo
Relationships
If you are eager loading a morphTo
relationship,
Eloquent will run multiple queries to fetch each type of related model.
You may add additional constraints to each of these queries using the
MorphTo
relation's constrain
method:
use Illuminate\Database\Eloquent\Builder;
use Illuminate\Database\Eloquent\Relations\MorphTo;
$comments = Comment::with(['commentable' => function (MorphTo $morphTo) {
$morphTo->constrain([
Post::class => function (Builder $query) {
$query->whereNull('hidden_at');
},
Video::class => function (Builder $query) {
$query->where('type', 'educational');
},
]);
}])->get();
In this example, Eloquent will only eager load posts that have not
been hidden and videos that have a type
value of
"educational".
Constraining Eager Loads With Relationship Existence
You may sometimes find yourself needing to check for the existence of
a relationship while simultaneously loading the relationship based on
the same conditions. For example, you may wish to only retrieve
User
models that have child Post
models
matching a given query condition while also eager loading the matching
posts. You may accomplish this using the withWhereHas
method:
use App\Models\User;
$users = User::withWhereHas('posts', function ($query) {
$query->where('featured', true);
})->get();
Lazy Eager Loading
Sometimes you may need to eager load a relationship after the parent model has already been retrieved. For example, this may be useful if you need to dynamically decide whether to load related models:
use App\Models\Book;
$books = Book::all();
if ($someCondition) {
$books->load('author', 'publisher');
}
If you need to set additional query constraints on the eager loading query, you may pass an array keyed by the relationships you wish to load. The array values should be closure instances which receive the query instance:
$author->load(['books' => function ($query) {
$query->orderBy('published_date', 'asc');
}]);
To load a relationship only when it has not already been loaded, use
the loadMissing
method:
$book->loadMissing('author');
Nested Lazy Eager Loading & morphTo
If you would like to eager load a morphTo
relationship,
as well as nested relationships on the various entities that may be
returned by that relationship, you may use the loadMorph
method.
This method accepts the name of the morphTo
relationship
as its first argument, and an array of model / relationship pairs as its
second argument. To help illustrate this method, let's consider the
following model:
<?php
use Illuminate\Database\Eloquent\Model;
class ActivityFeed extends Model
{
/**
* Get the parent of the activity feed record.
*/
public function parentable()
{
return $this->morphTo();
}
}
In this example, let's assume Event
, Photo
,
and Post
models may create ActivityFeed
models. Additionally, let's assume that Event
models belong
to a Calendar
model, Photo
models are
associated with Tag
models, and Post
models
belong to an Author
model.
Using these model definitions and relationships, we may retrieve
ActivityFeed
model instances and eager load all
parentable
models and their respective nested
relationships:
$activities = ActivityFeed::with('parentable')
->get()
->loadMorph('parentable', [
Event::class => ['calendar'],
Photo::class => ['tags'],
Post::class => ['author'],
]);
Preventing Lazy Loading
As previously discussed, eager loading relationships can often
provide significant performance benefits to your application. Therefore,
if you would like, you may instruct Laravel to always prevent the lazy
loading of relationships. To accomplish this, you may invoke the
preventLazyLoading
method offered by the base Eloquent
model class. Typically, you should call this method within the
boot
method of your application's
AppServiceProvider
class.
The preventLazyLoading
method accepts an optional
boolean argument that indicates if lazy loading should be prevented. For
example, you may wish to only disable lazy loading in non-production
environments so that your production environment will continue to
function normally even if a lazy loaded relationship is accidentally
present in production code:
use Illuminate\Database\Eloquent\Model;
/**
* Bootstrap any application services.
*
* @return void
*/
public function boot()
{
Model::preventLazyLoading(! $this->app->isProduction());
}
After preventing lazy loading, Eloquent will throw a
Illuminate\Database\LazyLoadingViolationException
exception
when your application attempts to lazy load any Eloquent
relationship.
You may customize the behavior of lazy loading violations using the
handleLazyLoadingViolationsUsing
method. For example, using
this method, you may instruct lazy loading violations to only be logged
instead of interrupting the application's execution with exceptions:
Model::handleLazyLoadingViolationUsing(function ($model, $relation) {
$class = get_class($model);
info("Attempted to lazy load [{$relation}] on model [{$class}].");
});
Inserting & Updating Related Models
The save
Method
Eloquent provides convenient methods for adding new models to
relationships. For example, perhaps you need to add a new comment to a
post. Instead of manually setting the post_id
attribute on
the Comment
model you may insert the comment using the
relationship's save
method:
use App\Models\Comment;
use App\Models\Post;
$comment = new Comment(['message' => 'A new comment.']);
$post = Post::find(1);
$post->comments()->save($comment);
Note that we did not access the comments
relationship as
a dynamic property. Instead, we called the comments
method
to obtain an instance of the relationship. The save
method
will automatically add the appropriate post_id
value to the
new Comment
model.
If you need to save multiple related models, you may use the
saveMany
method:
$post = Post::find(1);
$post->comments()->saveMany([
new Comment(['message' => 'A new comment.']),
new Comment(['message' => 'Another new comment.']),
]);
The save
and saveMany
methods will persist
the given model instances, but will not add the newly persisted models
to any in-memory relationships that are already loaded onto the parent
model. If you plan on accessing the relationship after using the
save
or saveMany
methods, you may wish to use
the refresh
method to reload the model and its
relationships:
$post->comments()->save($comment);
$post->refresh();
// All comments, including the newly saved comment...
$post->comments;
Recursively Saving Models & Relationships
If you would like to save
your model and all of its
associated relationships, you may use the push
method. In
this example, the Post
model will be saved as well as its
comments and the comment's authors:
$post = Post::find(1);
$post->comments[0]->message = 'Message';
$post->comments[0]->author->name = 'Author Name';
$post->push();
The pushQuietly
method may be used to save a model and
its associated relationships without raising any events:
$post->pushQuietly();
The create
Method
In addition to the save
and saveMany
methods, you may also use the create
method, which accepts
an array of attributes, creates a model, and inserts it into the
database. The difference between save
and
create
is that save
accepts a full Eloquent
model instance while create
accepts a plain PHP
array
. The newly created model will be returned by the
create
method:
use App\Models\Post;
$post = Post::find(1);
$comment = $post->comments()->create([
'message' => 'A new comment.',
]);
You may use the createMany
method to create multiple
related models:
$post = Post::find(1);
$post->comments()->createMany([
['message' => 'A new comment.'],
['message' => 'Another new comment.'],
]);
You may also use the findOrNew
, firstOrNew
,
firstOrCreate
, and updateOrCreate
methods to
create and update models on
relationships.
Note:
Before using thecreate
method, be sure to review the mass assignment documentation.
Belongs To Relationships
If you would like to assign a child model to a new parent model, you
may use the associate
method. In this example, the
User
model defines a belongsTo
relationship to
the Account
model. This associate
method will
set the foreign key on the child model:
use App\Models\Account;
$account = Account::find(10);
$user->account()->associate($account);
$user->save();
To remove a parent model from a child model, you may use the
dissociate
method. This method will set the relationship's
foreign key to null
:
$user->account()->dissociate();
$user->save();
Many To Many Relationships
Attaching / Detaching
Eloquent also provides methods to make working with many-to-many
relationships more convenient. For example, let's imagine a user can
have many roles and a role can have many users. You may use the
attach
method to attach a role to a user by inserting a
record in the relationship's intermediate table:
use App\Models\User;
$user = User::find(1);
$user->roles()->attach($roleId);
When attaching a relationship to a model, you may also pass an array of additional data to be inserted into the intermediate table:
$user->roles()->attach($roleId, ['expires' => $expires]);
Sometimes it may be necessary to remove a role from a user. To remove
a many-to-many relationship record, use the detach
method.
The detach
method will delete the appropriate record out of
the intermediate table; however, both models will remain in the
database:
// Detach a single role from the user...
$user->roles()->detach($roleId);
// Detach all roles from the user...
$user->roles()->detach();
For convenience, attach
and detach
also
accept arrays of IDs as input:
$user = User::find(1);
$user->roles()->detach([1, 2, 3]);
$user->roles()->attach([
1 => ['expires' => $expires],
2 => ['expires' => $expires],
]);
Syncing Associations
You may also use the sync
method to construct
many-to-many associations. The sync
method accepts an array
of IDs to place on the intermediate table. Any IDs that are not in the
given array will be removed from the intermediate table. So, after this
operation is complete, only the IDs in the given array will exist in the
intermediate table:
$user->roles()->sync([1, 2, 3]);
You may also pass additional intermediate table values with the IDs:
$user->roles()->sync([1 => ['expires' => true], 2, 3]);
If you would like to insert the same intermediate table values with
each of the synced model IDs, you may use the
syncWithPivotValues
method:
$user->roles()->syncWithPivotValues([1, 2, 3], ['active' => true]);
If you do not want to detach existing IDs that are missing from the
given array, you may use the syncWithoutDetaching
method:
$user->roles()->syncWithoutDetaching([1, 2, 3]);
Toggling Associations
The many-to-many relationship also provides a toggle
method which "toggles" the attachment status of the given related model
IDs. If the given ID is currently attached, it will be detached.
Likewise, if it is currently detached, it will be attached:
$user->roles()->toggle([1, 2, 3]);
You may also pass additional intermediate table values with the IDs:
$user->roles()->toggle([
1 => ['expires' => true],
2 => ['expires' => true],
]);
Updating A Record On The Intermediate Table
If you need to update an existing row in your relationship's
intermediate table, you may use the updateExistingPivot
method. This method accepts the intermediate record foreign key and an
array of attributes to update:
$user = User::find(1);
$user->roles()->updateExistingPivot($roleId, [
'active' => false,
]);
Touching Parent Timestamps
When a model defines a belongsTo
or
belongsToMany
relationship to another model, such as a
Comment
which belongs to a Post
, it is
sometimes helpful to update the parent's timestamp when the child model
is updated.
For example, when a Comment
model is updated, you may
want to automatically "touch" the updated_at
timestamp of
the owning Post
so that it is set to the current date and
time. To accomplish this, you may add a touches
property to
your child model containing the names of the relationships that should
have their updated_at
timestamps updated when the child
model is updated:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Comment extends Model
{
/**
* All of the relationships to be touched.
*
* @var array
*/
protected $touches = ['post'];
/**
* Get the post that the comment belongs to.
*/
public function post()
{
return $this->belongsTo(Post::class);
}
}
Warning!!
Parent model timestamps will only be updated if the child model is updated using Eloquent'ssave
method.