Eloquent Relationships Cheat Sheet

A cheat sheet for Laravel’s Eloquent ORM version 5.5.

One to One Relationship

Demo details:

In this demo we have 2 models (Owner and Car), and 2 tables (owners and cars).

Business Rules:

The Owner can own one Car.The Car can be owned by one Owner.

Relations Diagram:

Relationship Details:

The Cars table should store the Owner ID.

Eloquent Models:

class Owner{public function car(){return $this->hasOne(Car::class);}}

class Car{public function owner(){return $this->belongsTo(Owner::class);}}

Database Migrations:

Schema::create('owners', function (Blueprint $table) {$table->increments('id');$table->string('name');});

Schema::create('cars', function (Blueprint $table) {$table->increments('id');$table->string('name');

$table->integer('owner\_id')->unsigned()->index()->nullable();  
$table->foreign('owner\_id')->references('id')->on('owners');  

});

Store Records:

// Create relation between Owner and Car.

$owner->car()->save($car);

// Create relation between Car and Owner.

$car->owner()->associate($owner)->save();

Retrieve Records:

// Get Owner Car

$owner->car;

// Get Car Owner

$car->owner;

One to Many Relationship

Demo details:

In this demo we have 2 models (Thief and Car), and 2 tables (thieves and cars).

Business Rules:

The Thief can steal many Cars.The Car can be stolen by one Thief.

Relations Diagram:

Relationship Details:

The Cars table should store the Thief ID.

Eloquent Models:

class Thief{public function cars(){return $this->hasMany(Car::class);}}

class Car{public function thief(){return $this->belongsTo(Thief::class);}}

Database Migrations:

Schema::create('thieves', function (Blueprint $table) {$table->increments('id');$table->string('name');});

Schema::create('cars', function (Blueprint $table) {$table->increments('id');$table->string('name');

$table->integer('thief\_id')->unsigned()->index()->nullable();  
$table->foreign('thief\_id')->references('id')->on('thieves');  

});

Store Records:

// Create relation between Thief and Car.

$thief->cars()->saveMany([$car1,$car2,]);

// Or use the save() function for single model.

$thief->cars()->save($car);

// Create relation between Car and Thief.

$car->thief()->associate($thief)->save();

Retrieve Records:

// Get Thief Car

$thief->cars;

// Get Car Thief

$car->thief;

Polymorphic One to Many Relationship

Demo details:

In this demo we have 3 models (Man, Woman and Car), and 3 tables (men, women and cars).

Business Rules:

The Man (buyer) can buy many Cars. The Woman (buyer) can buy many Cars.The Car can be bought by one buyer (Man or Woman).

Relations Diagram:

Relationship Details:

The Car table should store the Buyer ID and the Buyer Type. “buyer” is a name given to a group of models (Man and Woman). And it’s not limited to two. The buyer type is the real name of the model.

Eloquent Models:

class Man{public function cars(){return $this->morphMany(Car::class, 'buyer');}}

class Woman{public function cars(){return $this->morphMany(Car::class, 'buyer');}}

class Car{public function buyer(){return $this->morphTo();}}

Database Migrations:

Schema::create('men', function (Blueprint $table) {$table->increments('id');$table->string('name');});

Schema::create('women', function (Blueprint $table) {$table->increments('id');$table->string('name');});

Schema::create('cars', function (Blueprint $table) {$table->increments('id');$table->string('name');

$table->integer('buyer\_id')->unsigned()->index()->nullable();  
$table->string('buyer\_type')->nullable();     
// or use $table->morphs(‘buyer’); instead of "buyer\_id" and "buyer\_type"

});

Store Records:

// Create relation between buyer (Man/Woman) and Car.

$man->cars()->saveMany([$car1,$car2,]);

$woman->cars()->saveMany([$car1,$car2,]);

// Or use the save() function for single model.

$man->cars()->save($car);$woman->cars()->save($car);

// Create relation between Car and buyer (Men/Women).

$car1->buyer()->associate($man)->save();$car2->buyer()->associate($woman)->save();

Retrieve Records:

// Get buyer (Man/Woman) Cars

$men->cars$women->cars

// Get Car buyer (Man and Woman)

$car->buyer

Many to Many Relationship

Demo details:

In this demo we have 2 models (Driver and Car), and 3 tables (drivers, cars and a pivot table named car_driver).

Business Rules:

The Driver can drive many Cars.The Car can be driven by many Drivers.

Relations Diagram:

Relationship Details:

The Pivot table “car_driver” should store the Driver ID and the Car ID.

Eloquent Models:

class Driver{public function cars(){return $this->belongsToMany(Car::class);}}

class Car{public function drivers(){return $this->belongsToMany(Driver::class);}}

Database Migrations:

Schema::create('drivers', function (Blueprint $table) {$table->increments('id');$table->string('name');});

Schema::create('cars', function (Blueprint $table) {$table->increments('id');$table->string('name');});

Schema::create('car_driver', function (Blueprint $table) {$table->increments('id');

$table->integer('car\_id')->unsigned()->index();  
$table->foreign('car\_id')->references('id')->on('cars')->onDelete('cascade');

$table->integer('driver\_id')->unsigned()->index();  
$table->foreign('driver\_id')->references('id')->on('drivers')->onDelete('cascade');  

});

Store Records:

// Create relation between Driver and Car.

$driver->cars()->attach([$car1->id,$car2->id,]);

// Or use the sync() function to prevent duplicated relations.

$driver->cars()->sync([$car1->id,$car2->id,]);

// Create relation between Car and Driver.

$car->drivers()->attach([$driver1->id,$driver2->id,]);

// Or use the sync() function to prevent duplicated relations.

$car->drivers()->sync([$driver1->id,$driver2->id,]);

Retrieve Records:

// Get Driver Car

$driver->cars

// Get Car Drivers

$car->drivers

Polymorphic Many to Many Relationship

Demo details:

In this demo we have 3 models (Valet, Owner and Car), and 4 tables (valets, owners, cars and drivers).

Business Rules:

The Valet (driver) can drive many Cars. The Owner (driver) can drive many Cars.The Car can be driven by many drivers (Valet or/and Owner).

Relations Diagram:

Relationship Details:

The Pivot table “drivers” should store the Driver ID, Driver Type and the Car ID.“driver” is a name given to a group of models (Valet and Owner). And it’s not limited to two. The driver type is the real name of the model.

Eloquent Models:

class Valet{public function cars(){return $this->morphToMany(Car::class, 'driver');}}

class Owner{public function cars(){return $this->morphToMany(Car::class, 'driver');}}

class Car{public function valets(){return $this->morphedByMany(Valet::class, 'driver');}

public function owners()  
{  
    return $this->morphedByMany(Owner::class, 'driver');  
}  

}

Database Migrations:

Schema::create('valets', function (Blueprint $table) {$table->increments('id');$table->string('name');});

Schema::create('owners', function (Blueprint $table) {$table->increments('id');$table->string('name');});

Schema::create('drivers', function (Blueprint $table) {$table->increments('id');

$table->integer('driver\_id')->unsigned()->index();  
$table->string('driver\_type');  
// or use $table->morphs(‘driver’); instead of "driver\_id" and "driver\_type"

$table->integer('car\_id')->unsigned()->index();  
$table->foreign('car\_id')->references('id')->on('cars')->onDelete('cascade');  

});

Store Records:

// Create relation between driver (Valet/Owner) and Car.

$valet->cars()->saveMany([$car1, $car2]);$owner->cars()->saveMany([$car1, $car2]);

// Or use the save() function for single model.

$valet->cars()->save($car1);$owner->cars()->save($car1);

// Create relation between Car and driver (Valet/Owner).

$car->valets()->attach([$valet1->id,$valet2->id,]);

$car->owners()->attach([$owner1->id,$owner2->id,]);

// Or use the sync() function to prevent duplicated relations.

$car->valets()->sync([$valet1->id,$valet2->id,]);

$car->owners()->sync([$owner1->id,$owner2->id,]);

Retrieve Records:

// Get driver (Valet/Owner) Cars

$valet->cars$owner->cars

// Get Car drivers (Valet and Owner)

$car->owners$car->valets

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