Php registration error validation - php

Question

I have been practicing with PHP and mongodb. I am developing a simple web application but using OOP.
I created a class called user which has my methods to do with user like addUser, deleteUser etc. For add user, I would like for the form to carry out some simple validation tasks, but i am not sure how. Here is the class to add a new user:
function createUser($username, $name, $email, $password){
$user = array(
'username' => $username,
'name' => $name,
'email' => $email,
'password' => $password
);
if ($this->db->count(array('username' => $username)) == 0) {
$this->db->insert($user);
return true;
} else {
echo 'username taken';
}
}
And the html:
<?php
session_start();
include_once 'user.php';
include './templates/header.php';
if (isset($_POST['register']) && ($_POST['register']) == ($_POST["register"])) {
$user = new User();
$return = $user->createUser(
$_POST['username'],
$_POST['name'],
$_POST['email'],
$_POST['password'],
$_POST['password2']);
}
if ($return == true) {
echo 'you have successfully registered';
} else {
echo '</br>' . 'sorry, try again';
}
?>
<div class="container">
<div class="jumbotron">
<form method="post" action="">
<label>Username: </label><br>
<input name="username" type="text" ><br><br>
<label>Name: </label><br>
<input name="name" type="text"><br><br>
<label>Email: </label><br>
<input name="email" type="email" ><br><br>
<label>Password: </label><br>
<input name="password" type="password" ><br><br><br>
<label>Repeat Password: </label><br>
<input name="password2" type="password" ><br><br><br>
<input name="register" class="btn btn-primary btn-lg" type="submit" value="Register"><br>
</form>
</div>
</div>
Please feel free to correct me on other mistakes you may notice. I know there is bound to be some.

Answer 1

i wrote a simple example for you its simple and useful
class validation {
public $currentValue;
public $values = array();
public $errors = array();
public function __construct() {
parent::__construct();
// echo "burasi model sayfasi ";
}
public function post($key){
if(isset($_POST[$key])){
$this->values[$key] = $_POST[$key];
$this->currentValue = $key;
return $this;
}else{ die("hi boo boo ! your form values are empty");}
}
public function isEmpty(){
if(empty($this->values[$this->currentValue])){
$message='the form is emppty';
$this->errors[$this->currentValue]['empty'] =''.$message.'';
}
return $this;
}
public function submit(){
if(empty($this->errors)){
return true;
}else{
return false;
}
}
}
this is an example so how can you use it ?
firstly you need yo call the class
$form = new validation ();
$form->post("all you need just write post name here ")
->isEmpty();
if($form->submit()){
//everyting is ok !
you cann add delet or update data
}else{
$data["error"] = $form->errors; // and we sett the errorr mesages to the array now you can show the user the errormesages ! well done
}
}