In this article, we will see laravel 8 one to one relationship example also you can use one to one relationships in laravel 6 and laravel 7. One to one relationship is a very basic type of database relationship. You have one table with a primary key that references the id of the other table. For one to one relationships using hasOne and belongsTo the method in the model for accessing each other model. Also, we will create migration with a foreign key, retrieve records using the model, insert new records, update records, etc.

So, let's see one to one relationship in laravel 8 and laravel 8 relationship with the condition.

We will create a User and Phone table. User a 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.

 

 

Now, we have to create migration for users and phones table. we will also add foreign keys to the user's table.

Create Migration of Users Table

Schema::create('users', function (Blueprint $table) {

    $table->increments('id');

    $table->string('name');

    $table->string('email')->unique();

    $table->timestamps();

});

Create Migration of Phones Table with Foreign Key

Schema::create('phones', function (Blueprint $table) {

    $table->increments('id');

    $table->integer('user_id')->unsigned();

    $table->string('phone_no');

    $table->timestamps();
    

    $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');

});

 

In the user model, we can create a phone() function and add a relation to the phone model using hasOne method.

User Model:

<?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);
    }
}

 

 

Phone Model:

we can access the Phone model from our User model. Next, let's define a relationship on the Phone the 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);
    }
}

 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

public function user()
{
    return $this->belongsTo(User::class, 'foreign_key');
}

 

Once the relationship is defined, we may retrieve the related record using Eloquent's dynamic properties. So, here we can use the User model with a phone function.

$phone = User::find(1)->phone;

$user = Phone::find(1)->user;

 

 Using model find the user and save the phone number.

$user = User::find(1);
 
$phone = new Phone;
$phone->phone_no = '9876543210';
 
$user->phone()->save($phone);

 

 

$phone = Phone::find(1);
 
$user = User::find(1);
 
$phone->user()->associate($user)->save();

 

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