public function assignProject($user_id)
{
if ($this->validateAssignExist($user_id) == false) {
$projectAssignment = new ProjectAssignments();
$projectAssignment->user_id = $user_id;
$projectAssignment->project_id = $this->id;
$projectAssignment->save();
} else {
throw new ExitException('Exiting error!');
}
}
