I'm not 100% understanding your question, but will do my best to answer it. I believe you are referring to how to validate values on form submit through PHP.
You can do this the old way without jQuery using a standard POST or GET
form.html
<html>
<head>
<title>Form Page</title>
</head>
<body>
<form action="validation.php" method="POST">
<input type="text" name="email" />
</form>
</body>
</html>
validation.php
<?php
$email = $_POST['email'];
//any validation here (this validates if email has @ sign)
$is_valid = strpos($email, "@");
if($is_valid === false){
//@ sign is not in string thus email is invalid, send message
echo "Error";
} else{
//is valid
echo "Valid";
}
?>
The $_POST is used to receive variables that were posted. The $_GET is used to receive variables that are sent GET method. The GET method sends data through the url as a query string. Consequently, it should not be used for sensitive information as this poses a security risk.
You can also use the more recent jQuery method using AJAX so it doesn't reload the entire page to validate.
form_jquery.html
<html>
<head>
<title>Form Page</title>
<script src="http://code.jquery.com/jquery-1.9.0.min.js" type="text/javascript"></script>
<script type="text/javascript">
$(document).ready(function(){
$("form").submit(function(){
//do javascript validation here
//do php validation here
$.post("validation.php", {email: $("#email").val()}, function(data){
alert(data); //validation msg
}, "text");
});
});
</script>
</head>
<body>
<form>
<input id="email" type="text" name="email" />
</form>
</body>
</html>
If JavaScript is disabled on the client, you cannot use JavaScript client validation or jQuery (jQuery is a JavaScript framework). You can only use server-side.
In response to this code:
if(isset($code) && $code == 1)
The isset checks to see if $code has a value (i.e. not null) and the $code == 1 checks to evaluate if $code is equal to 1. If that condition is met, it assigns the CSS class "error" to the input text box giving it a red border.
Applying your example, jQuery would be best suited for you.
name_jquery.html
<html>
<head>
<title>Form Page</title>
<script src="http://code.jquery.com/jquery-1.9.0.min.js" type="text/javascript"></script>
<style type="text/css">
.error{border:1px solid red; }
</style>
<script type="text/javascript">
$(document).ready(function(){
$("form").submit(function(){
//do javascript validation here
//do php validation here
$.post("validation.php", {email: $("#name").val()}, function(data){
if(data.error == "1"){ //1 means error
$("#name").addClass("error");
$("body").append("<p id=\"error\">"+data.message+"</p>");
} else{
alert('your form is valid');
//clear css error class in case was invalid before
$("#name").removeClass("error");
$("#error").remove();
}
}, "json");
});
});
</script>
</head>
<body>
<form>
<input id="name" type="text" name="name" />
</form>
</body>
</html>
validation.php
<?php
$name=trim($_POST["name"]);
if(empty($name)) {
$error= "error : You did not enter a name.";
$code= "1" ;
} else{
$code = "0";
}
echo json_encode("error"=> $code, "message"=>$error);
?>
