Accessors (Getter) & Mutators (Setter) On a Pivot Table in Laravel

Question

I have a pivot table that connects users to workspaces. On the pivot table, I also have a column for role, which defines the users role for that workspace. Can I provide Accessor (Getter) & Mutator (Setter) methods on the role inside the pivot table? I have been trying to look all over, but details on pivot tables in eloquent are pretty sparse.

I am not sure if I have to setup a custom pivot model? If I do, an example would be awesome as the documentation on pivot models is very basic.

Thanks.

Answer 1

If all you need to do is access additional fields on the pivot table, you just need to use the withPivot() method on the relationship definition:

class User extends Model {
    public function workspaces() {
        return $this->belongsToMany('App\Models\Workspace')->withPivot('role');
    }
}

class Workspace extends Model {
    public function users() {
        return $this->belongsToMany('App\Models\User')->withPivot('role');
    }
}

Now your role field will be available on the pivot table:

$user = User::first();

// get data
foreach($user->workspaces as $workspace) {
    var_dump($workspace->pivot->role);
}

// set data
$workspaceId = $user->workspaces->first()->id;
$user->workspaces()->updateExistingPivot($workspaceId, ['role' => 'new role value']);

---

If you really need to create accessors/mutators for your pivot table, you will need to create a custom pivot table class. I have not done this before, so I don't know if this will actually work, but it looks like you would do this:

Create a new pivot class that contains your accessors/mutators. This class should extend the default Pivot class. This new class is the class that is going to get instantiated when User or Workspace creates a Pivot model instance.

namespace App\Models;
use Illuminate\Database\Eloquent\Relations\Pivot;
class UserWorkspacePivot extends Pivot {
    getRoleAttribute() {
        ...
    }
    setRoleAttribute() {
        ...
    }
}

Now, update your User and Workspace models to create this new pivot table class, instead of the default one. This is done by overriding the newPivot() method provided by the Model class. You want to override this method so that you create an instance of your new UserWorkspacePivot class, instead of the default Pivot class.

class User extends Model {
    // normal many-to-many relationship to workspaces
    public function workspaces() {
        // don't forget to add in additional fields using withPivot()
        return $this->belongsToMany('App\Models\Workspace')->withPivot('role');
    }

    // method override to instantiate custom pivot class
    public function newPivot(Model $parent, array $attributes, $table, $exists) {
        return new UserWorkspacePivot($parent, $attributes, $table, $exists);
    }
}

class Workspace extends Model {
    // normal many-to-many relationship to users
    public function users() {
        // don't forget to add in additional fields using withPivot()
        return $this->belongsToMany('App\Models\User')->withPivot('role');
    }

    // method override to instantiate custom pivot class
    public function newPivot(Model $parent, array $attributes, $table, $exists) {
        return new UserWorkspacePivot($parent, $attributes, $table, $exists);
    }
}

Answer 2

I figured out how to use Accessors and Mutators on the Pivot table (I'm using Laravel 5.8)

You must use using() on your belongsToMany relationships, for example:

namespace App;
use Illuminate\Database\Eloquent\Model;

class User extends Model {
    public function workspaces() {
        return $this->belongsToMany('App\Workspace')->using('App\UserWorkspace');
    }
}

namespace App;
use Illuminate\Database\Eloquent\Model;

class Workspace extends Model {
    public function users() {
        return $this->belongsToMany('App\User')->using('App\UserWorkspace');
    }
}

So, use your Pivot model:

namespace App;
use Illuminate\Database\Eloquent\Relations\Pivot;

class UserWorkspace extends Pivot {
    public function getRoleAttribute() {
        // your code to getter here

    }
    public function setRoleAttribute($value) {
        // your code to setter here
    }
}