How can I validate inputs directly from the database without page reloading? - php

Question

I'm just a PHP starter and now I want to learn JQUERY, on my learning process I practice on validating inputs usually I validate my inputs using a pure PHP code only and every time I validate the inputs the page reloads and now I want to improve in doing things I found some articles like http://api.jquery.com/jQuery.ajax/, http://api.jquery.com/jQuery.post/ (can't post other links) but I am more confused because they have different approach and I want to use the approach from the JQUERY tutorial but I haven't found any good tutorials and there is no tutorials on JQUERY's site that is using a database, usually I code like this:
<form method="post">
<label for="Username">Username:</label>
<input id="Username" type="text" name="username">
<?php
session_start();
if(isset($_SESSION['msg'])){
$msg=$_SESSION['msg'];
echo '<label for="Username">'.$msg.'</label>';
?>
<input type="submit" name="reg">
</form>
<?php
if(isset($_POST['reg'])){
$result=//check username from database here
if($result){
$_SESSION['msg']='username not available.';
}
else {
$_SESSION['msg']='username available.';
}
}
?>
Now I want to learn how can I validate inputs directly from the database without reloading the page? I don't know where should I start, what to add in my code. Any help, advice or suggestions will be really a big help for me :)

Answer 1

first, in your form add a onSubmit function
<form name='myform' type='POST' action='http://www.action.fr' onSubmit="return check_form()">
you can do this in ajax like that
function check_form()
{
var user = $('#Username').val(); // Username is the id of your input
var password = $('#password').val(); // password is the id of your input
$.ajax(
{
type:"POST", // or get as you want
url:"myfile.php", // it is the php file which can do the job
data: "user="+user+"&password="+password, // the param to send to your file,
success:function(msg)
{
;// msg is the result of your 'myfile.php', everything you write is in the msg var
}
});
}
in your php file you can get your data like this :
$user = $_POST['user'];
$password = $_POST['password'];
// if your type is get then use $_GET instead of $_POST
tell me if you have any problem with my code.

Answer 2

Write your validation script as though you're expecting a page refresh. Instead of outputting error messages, put them in a JSON array and print the JSON data. Then call the script from the AJAX function. It's really that simple.
<?php
// validate.php
$sampleInput_number = isset($_POST['sampleInput_number']) ? $_POST['sampleInput_number'] : "";
$errors = array();
if (trim($sampleInput_number) == "" || !is_numeric(trim($sampleInput_number)) {
$errors[] = "SampleInput_number must be a number!";
}
// sample input must also match a value from the database
if (!matchesDBValue($sampleInput_number)) {
$errors[] = "SampleInput_number must match a value from the database!";
}
function matchesDBValue($value) {
$retval = false;
// compare to db values here...
return $retval;
}
echo json_encode($errors);
Your form would look something like this:
<form action="" method="post" id="theForm">
<input type="text" name="sampleInput_number" id="sampleInput_number" />
<input type="button" id="formSubmit" value="Submit" />
</form>
And your javascript would look like this:
<script language="javascript" type="text/javascript">
$(#formSubmit).on("click", function() {
$.post("validate.php",
{
sampleInput_number: $("#sampleInput_number").val()
}, function(data) {
// check returned json data
// perform action based on results
if (no_errors) {
$("#theForm").submit();
}
}, "json"
);
});
</script>