🔹 1️⃣ One-to-One

👉 Ek record ka sirf ek related record

Example: User → Profile

// User.php

class User extends Model

{

    public function profile()

    {

        return $this->hasOne(Profile::class, 'user_id', 'id');

    }

}

// Profile.php

class Profile extends Model

{

    public function user()

    {

        return $this->belongsTo(User::class, 'user_id', 'id');

    }

}

🔹 2️⃣ One-to-Many

👉 Ek record ke multiple related records

Example: User → Tasks

// User.php

class User extends Model

{

    public function tasks()

    {

        return $this->hasMany(TaskModel::class, 'UserID', 'id');

    }

}

// TaskModel.php

class TaskModel extends Model

{

    public function user()

    {

        return $this->belongsTo(User::class, 'UserID', 'id');

    }

}

🔹 3️⃣ Many-to-Many

👉 Multiple records ek-dusre se relate

👉 Pivot table required

Example: Users ↔ Roles

// User.php

class User extends Model

{

    public function roles()

    {

        return $this->belongsToMany(

            Role::class,

            'role_user',

            'user_id',

            'role_id'

        );

    }

}

// Role.php

class Role extends Model

{

    public function users()

    {

        return $this->belongsToMany(

            User::class,

            'role_user',

            'role_id',

            'user_id'

        );

    }

}

🔹 4️⃣ Has One Through

👉 Intermediate table ke through ek related record

Example: Country → User → Passport

// Country.php

class Country extends Model

{

    public function passport()

    {

        return $this->hasOneThrough(

            Passport::class,

            User::class,

            'country_id', // Foreign key on users table

            'user_id',    // Foreign key on passports table

            'id',         // Local key on countries table

            'id'          // Local key on users table

        );

    }

}

🔹 5️⃣ Has Many Through

👉 Intermediate table ke through multiple records

Example: Country → Users → Posts

// Country.php

class Country extends Model

{

    public function posts()

    {

        return $this->hasManyThrough(

            Post::class,

            User::class,

            'country_id', // Foreign key on users table

            'user_id',    // Foreign key on posts table

            'id',         // Local key on countries table

            'id'          // Local key on users table

        );

    }

}

🔹 6️⃣ Polymorphic Relationships

👉 Ek model multiple models ke saath relate ho sakta hai

Example: Comments → Posts / Videos

// Comment.php

class Comment extends Model

{

    public function commentable()

    {

        return $this->morphTo();

    }

}

// Post.php

class Post extends Model

{

    public function comments()

    {

        return $this->morphMany(Comment::class, 'commentable');

    }

}

// Video.php

class Video extends Model

{

    public function comments()

    {

        return $this->morphMany(Comment::class, 'commentable');

    }

}

🧠 PART 2: Quick Summary (Same Level as JOINs)

One-to-One → ek record = ek related record

One-to-Many → ek record = multiple related records

Many-to-Many → dono side multiple, pivot table required

Has One Through → intermediate ke through single relation

Has Many Through → intermediate ke through multiple relations

Polymorphic → ek model, multiple parent types