Laravel 9 One To One Relationship Tutorial With Example

Hi guys,

Today, I am exaplian laravel 9 one to one relationship tutorial with example. One to One model relationship is very simple and basic. When one table refers to single row in another table that is called a one-to-one relationship. This tutorial will see how the One To One Relationship in Laravel 9 is working with an example.

Eloquent relationships are defined as methods on your Eloquent model classes. Inside this article we will see the concept of laravel 9 One to One Eloquent relationship as well as we will implement inverse of one to one relationship i.e belongs to.

So let's start following example:

Now we have to create migration of "users" and "phones" table. we will also add foreign key with users table. so let's create like as below:

users table migration:

<?php
  
use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;
  
return new class extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('users', function (Blueprint $table) {
            $table->id();
            $table->string('name');
            $table->string('email')->unique();
            $table->timestamp('email_verified_at')->nullable();
            $table->string('password');
            $table->rememberToken();
            $table->timestamps();
        });
    }
  
    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('users');
    }
};

<?php
  
use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;
  
return new class extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('phones', function (Blueprint $table) {
            $table->id();
            $table->foreignId('user_id')->constrained('users');
            $table->string('phone');
            $table->timestamps();
        });
    }
  
    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('phones');
    }
};

Here, we will create User and Phone table model. we will also use "hasOne()" and "belongsTo()" for relationship of both model.

<?php
  
namespace App\Models;
  
use Illuminate\Contracts\Auth\MustVerifyEmail;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Foundation\Auth\User as Authenticatable;
use Illuminate\Notifications\Notifiable;
use Laravel\Sanctum\HasApiTokens;
  
class User extends Authenticatable
{
    use HasApiTokens, HasFactory, Notifiable;
  
    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = [
        'name',
        'email',
        'password',
    ];
 
    /**
     * The attributes that should be hidden for serialization.
     *
     * @var array
     */
    protected $hidden = [
        'password',
        'remember_token',
    ];
  
    /**
     * The attributes that should be cast.
     *
     * @var array
     */
    protected $casts = [
        'email_verified_at' => 'datetime',
    ];
  
    /**
     * Get the phone associated with the user.
     * 
     * Syntax: return $this->hasOne(Phone::class, 'foreign_key', 'local_key');
     *
     * Example: return $this->hasOne(Phone::class, 'user_id', 'id');        
     */
    public function phone()
    {
        return $this->hasOne(Phone::class);
    }
}

<?php
  
namespace App\Models;
  
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
  
class Phone extends Model
{
    use HasFactory;
  
    /**
     * Get the user that owns the phone.
     * 
     * Syntax: return $this->belongsTo(Phone::class, 'foreign_key', 'owner_key');
     *
     * Example: return $this->belongsTo(Phone::class, 'user_id', 'id');        
     */
    public function user()
    {
        return $this->belongsTo(User::class);
    }
}

<?php
  
namespace App\Http\Controllers;
  
use Illuminate\Http\Request;
use App\Models\User;
  
class UserController extends Controller
{
    /**
     * Write code on Method
     *
     * @return response()
     */
    public function index(Request $request)
    {
        $phone = User::find(1)->phone;
  
        dd($phone);
    }
}

<?php
  
namespace App\Http\Controllers;
  
use Illuminate\Http\Request;
use App\Models\Phone;
  
class UserController extends Controller
{
    /**
     * Write code on Method
     *
     * @return response()
     */
    public function index(Request $request)
    {
        $user = Phone::find(1)->user;
  
        dd($user);
    }
}

<?php
  
namespace App\Http\Controllers;
  
use Illuminate\Http\Request;
use App\Models\User;
use App\Models\Phone;
  
class UserController extends Controller
{
    /**
     * Write code on Method
     *
     * @return response()
     */
    public function index(Request $request)
    {
        $user = User::find(1);
   
        $phone = new Phone;
        $phone->phone = '9429343852';
           
        $user->phone()->save($phone);
    }
}

<?php
  
namespace App\Http\Controllers;
  
use Illuminate\Http\Request;
use App\Models\User;
use App\Models\Phone;
  
class UserController extends Controller
{
    /**
     * Write code on Method
     *
     * @return response()
     */
    public function index(Request $request)
    {
        $phone = Phone::find(1);
   
        $user = User::find(10);
           
        $phone->user()->associate($user)->save();
    }
}

I hope you understand of one to one relationship...