laravel 5.4 many to many relationship

问题

i have relationship many to many table 'admins' , 'pjt_roles' with pjt_role_admin. but,not working

i have 2 model

class Role

protected $table = 'pjt_roles';

public function Admin(){
    return $this->belongsToMany(Admin::class',pjt_role_admin');
}

class Admin

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

and table pjt_role_admin have attribute

1. admin_id from table admins

2. role_id from table pjt_roles

回答1:

Specify your pivot table in relationship. Default laravel assume admin_role as your pivot table because you have Admin and Role models

class Role

protected $table = 'pjt_roles';

public function Admin(){ // should be admins() for better readability
    return $this->belongsToMany(Admin::class, 'pjt_role_admin');
}

class Admin

public function Role(){ // should be roles() for better readability
    return $this->belongsToMany(Role::class, 'pjt_role_admin');
}

To determine the table name of the relationship's joining table, Eloquent will join the two related model names in alphabetical order. However, you are free to override this convention. You may do so by passing a second argument to the belongsToMany method.

Fetch Data

$admin = Admin::find(1);
$roles = $admin->Role; // should change to roles() in relationship for better readability

Save

$admin->Role()->attach($roleId);

details https://laravel.com/docs/5.4/eloquent-relationships#many-to-many

来源：https://stackoverflow.com/questions/51094443/laravel-5-4-many-to-many-relationship