one-to-many relationship doesn't work - php

Question

I am trying to create one-to-many relationship with 2 models, User and Role. So, I would like that one User can only have one role, and the Role can be assigned to more than User. I tried to follow the offical tutorial on https://laravel.com/docs/5.1/eloquent-relationships#one-to-many, and ended up with this:
class User extends Model
{
public function role()
{
return $this->belongsToMany('App\Admin\Role');
}
}
class Role extends Model
{
protected $table = 'roles';
public function users()
{
return $this->hasMany('App\Admin\User');
}
}
Based on that link, I think the Role is the same thing as the Post, one Role can be assigned to many User. However, this doesn't quite work, here is how I tried to access the role name for a specific User
$role_first = $user->role; // Eloquent\Collection
$role_second = $user->role(); // Eloquent\Relations\BelongsToMany
$role_first->role_title // 'Undefined property: Illuminate\Database\Eloquent\Collection::$role_title'
$role_second->role_title // exception 'ErrorException' with message 'Undefined property: Illuminate\Database\Eloquent\Relations\BelongsToMany::$role_title'
What is exactly wrong here?

Answer 1

In the User class
public function role()
{
// not $this->belongsToMany('App\Admin\Role');
return $this->belongsTo('App\Admin\Role');
}
Because you want a oneToMany not manyToMany relationship.

Answer 2

This should do it. Please give it a try
class User extends Model
{
public function role()
{
return $this->hasOne(App\Admin\Role::class);
}
}
// user belongs to one role
class Role extends Model
{
protected $table = 'roles';
public function users()
{
return $this->belongsTo(App\Admin\User::class);
}
}

Answer 3

User Model
class User extends Authenticatable{
public function roles(){
return $this->belongsTo('App\Admin\Role');
}
}
Role Model
class Role extends Model{
public function users(){
return $this->hasMany('App\Admin\User');
}
}
The user can have only one role, and the role can be assigned to many users.

Answer 4

Just make sure the relation
A User hasOne Role
A Role belongsToMany Users
so, in this condition
class User extends Model
{
public function role()
{
return $this->hasOne('App\Admin\Role');
}
}
class Role extends Model
{
protected $table = 'roles';
public function users()
{
return $this->belongsToMany('App\Admin\User');
}
}
and must check your user_id foreign constraint be 'unsigned' in your role migration table.