如何使用Laravel中嵌套的多对多关系从数据库中获取数据

Question

I'm working on Laravel Access Control Level (ACL) system. where is table contains some many to many to relationship. User table has many to many belongsToMany with Role Table and inversely many to many Role has belongsToMany with User table.Again, Role table has many to many belongsToMany relationship with Permission table and inversely Permission has many to many belongsToMany with Role table.

I want to run a query from user table which is fetch the all permissions of a role. this role is assigned to current user through roles table.

Here is my code sample.

User Model

 public function roles()
{
    return $this->belongstoMany(Role::class);
}

Role Model

 public function users()
{
    return $this->belongsToMany(User::class);
}

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

Permission Table

 public function roles()
{
    return $this->belongsToMany(Role::class);
}

I've tried this query using egar loading...

public function hasPermission($permission)
{
   if($this->roles()->with('permissions')->get()->pluck('permissions'))
   {
    return true;
   }
   return false;
} 

But it always return false.

Answer 1

There are many ways to check if one of the roles has given permission.

One example, add hasPermission method to User.php model

public function hasPermission($permission = '') {
  if ( empty($permisison) ) {
     return false;
  }

  /*
    Find all user roles that have given permission
  */
  $rolesWithPermission = $this
                          ->roles()
                            ->whereHas('permissions', function($query) use ($permission) {
                              $query->where('name', $permission);
                            })
                          ->get();

  /*
    If there is at least one role with given permission,
    user has permission
  */
  return $rolesWithPermission->count() > 0;
}

Or you can do one query with multiple joins between users, roles and permissions, and filter out the result with where('permissions.name', '=', $permission)