Trouble getting attribute of relation in Laravel - laravel-5

Question

I'm having a trouble with a relation in Laravel 5. the thing is that I have a table User and that user belongs to a Group for that, in the User model I have this:
public function group(){
return $this->belongsTo('App\models\Group');
}
The model Group have this attributes: name,unity,level, init_date. I also put there a default function to return a group as String, this is the code:
public function __toString(){
return $this->name.' Unity '.$this->unity;
}
So, the thing that in a view a have many users and for each of them I want to display the unity, name,date. When I call $user->group it returns me correctly the name and the unity in a String (because the _toString function) that means that he is really querying the group perfectly, but then, when I want to access a simple attribute as unity,date,or name with $user->group->name Laravel gives me this error:
Trying to get property of non-object
I even tried $user->group()->name then I gets: Undefined property: Illuminate\Database\Eloquent\Relations\BelongsTo::$name
Edited:
The model User:
class User extends Model implements AuthenticatableContract, CanResetPasswordContract {
use Authenticatable, CanResetPassword;
protected $table = 'users';
protected $fillable = ['email', 'password','estate','filial_id','perfil_id','rol','cat_teacher'];
/**
* The attributes excluded from the model's JSON form.
*
* #var array
*/
protected $hidden = ['password', 'remember_token'];
public function __toString(){
return $this->email;
}
public function filial(){
return $this->belongsTo('App\models\Filial');
}
public function perfil(){
return $this->belongsTo('App\models\Perfil','perfil_id');
}
public function grupo(){
return $this->belongsTo('App\models\Group','group_id','id');
}
}
The model Group:
class Group extends Model {
protected $table = 'groups';
protected $fillable = ['name','unity','date'];
public function filiales() {
return $this->belongsTo('App\models\Filial');
}
public function teacher(){
return $this->belongsTo('App\models\User','teacher_id');
}
public function users() {
return $this->hasMany('App\models\User');
}
}
Then, in the controller I made a dd($users) and there not appear the relations, appears other relations but not this one. In the view I want to print some of the attributes in a table, for that I have:
<td>{{$user->group}}</td>
<td>{{$user->group->unity}}</td>
The first line works perfectly, and I don´t know why.

Answer 1

The reason you're unable to return your group's name is that ->group() returns an instance of the query builder, and not an eloquent collection/object. Since a user belongs to a single group, modify your code in one of these two ways:
public function group(){
return $this->belongsTo('App\models\Group')->first();
}
And then access the group using one of the following methods:
$user = User::with("group")->where("id", "=", 1)->first();
$group = $user->group;
echo $group->name;
// OR
$user = User::where("id", "=", 1)->first();
$group = $user->group();
echo $group->name;
Or, leave the group() function as it is and access ->group()->first() on your $user object:
$user = User::where("id", "=", 1)->first();
$group = $user->group()->first();
echo $group->name;
Any of the above methods should properly return your group object's name (or other attributes). Check the Eloquent Documentation for detailed explanations on how to access these objects.