Laravel relationship not working: getConnectionName() Error

I have two tables users and user_details. I have linked users table as

public function userDetails()
{
    return $this->hasOne('App\Repositories\Models\UserDetails', 'id', 'user_id');
}

and linked user_details table as

public function user()
{
    return $this->belongsTo('App\Repository\Models\User');
}

While from UserController for accessing users data with details, if I try to access the data

return $this->user->with('userDetails')->get();

I get this type of error

FatalErrorException in HasRelationships.php line 488: Call to undefined method

App\Repositories\Models\UserDetails::getConnectionName()

Is there anything wrong?