Devise\Users\UsersRepository::findByUsername PHP Method

    public function findByUsername($username)
    {
        return $this->findByFieldAndValue('username', $username);
    }

 /**
  * Gets the proper UsersRepository find method for a user
  * based on the fieldname being passed in.
  *
  * @param  string  $fieldname
  * @param  string  $value
  * @return DvsUser
  */
 protected function retrieveUserFindMethodByField($fieldname, $value)
 {
     switch ($fieldname) {
         case "username":
             return $this->UsersRepository->findByUsername($value);
         case "email":
             return $this->UsersRepository->findByEmail($value);
     }
 }