Integrity constraint violation: 1048 Column 'user_id' cannot be null error occurs when assigning roles (Laravel 5.3)

问题:

Here's what I was doing before the error occurred

I'm trying to assign a role for a user from my users and roles table in a new table called `role_users'.

Role.php model

class Role extends Model{     public function users(){     return $this->belongsToMany('App\User','role_users', 'role_id', 'user_id');   } } 

User.php model

class User extends Model implements Authenticatable {   use \Illuminate\Auth\Authenticatable;    public function roles(){     return $this->belongsToMany('App\Role', 'role_users', 'user_id', 'role_id');   }     } 

I keep getting the error in this line from my AccountController.php

$roleuser = new User; $user_superadmin = Role::where('role_desc', 'Superadmin')->first(); $roleuser->roles()->attach($user_superadmin); /*this line specifically*/ 

I'm having Integrity constraint violation: 1048 Column 'user_id' cannot be null (SQL: insert into 'role_users' ('role_id', 'user_id') values (1, )). The users table is already updated and the user_id has already been saved to the database.

Can someone help me? I must have overlooked some important stuff.

回答1:

The problem here is that you don't attach role to any existing user, you just run:

$roleuser = new User; 

to create user object that is not save to database.

You should rather do something like this:

$roleuser = User::find(1); // find user with id 1 $user_superadmin = Role::where('role_desc', 'Superadmin')->first(); $roleuser->roles()->attach($user_superadmin); /*this line specifically*/ 

or

$roleuser = User::create(['name' => 'Sample user']); // create sample user $user_superadmin = Role::where('role_desc', 'Superadmin')->first(); $roleuser->roles()->attach($user_superadmin); /*this line specifically*/ 

You should also don't use $roleuser variable here, because it's obviously $user

回答2:

You can't attach relation to non existing user. Try to create user first:

$roleuser = User::create(['name' => 'John']); // Instead of new User; 

Or fetch user from DB:

$roleuser = User:find(1); 

文章来源: Integrity constraint violation: 1048 Column 'user_id' cannot be null error occurs when assigning roles (Laravel 5.3)