How to establish a hasManyThrough relationship in laravel for roles and permissions?

Question

So I understand how to load the roles for a user and the permissions for a role.

But now I have a user table, a role table, and a permission table. I also have role_user table for linking users and roles. And of course a permission_role for linking permissions and roles.

Now when I want to get all the roles for the user, I simply do something like this:

public function roles()
{
        return $this->belongsToMany('Uppdragshuset\AO\Tenant\Models\Role');
}

Similarly I can fetch permissions for roles like so:

public function permissions()
{
        return $this->belongsToMany(Permission::class);
}

Now according to the documentation on laravel, I can directly fetch permissions for a user by using the hasManyThrough relation too like so:

public function permissions()
{
    return $this->hasManyThrough(Permission::class, Role::class);
}

But this is returning with an error saying:

Unknown column 'role.user_id' in 'field list'

I think I understand why. Laravel is looking for user_id field in the role table but it does not understand that it is a many to many relation and it should look for it in the pivot table.

So what is the way around this? Is there a way around this in Eloquent or will I have to resort to using the query builder? And if yes, how to do the same thing with the query builder?

Answer 1

HasManyThrough can only be used to connect two HasMany relationships. There is no native relationship for your case.

I created a HasManyThrough relationship with unlimited levels and support for BelongsToMany :
Repository on GitHub

After the installation, you can use it like this:

class User extends Model {
    use \Staudenmeir\EloquentHasManyDeep\HasRelationships;

    public function permissions() {
        return $this->hasManyDeep(Permission::class, ['role_user', Role::class, 'permission_role']);
    }
}