Get a PHP variable from a page to another with AJAX

Question

I've got two pages:

1.php and 2.php

I'm trying to get a PHP variable from 2.php to 1.php through an AJAX request.

This is the script in 1.php

<script>
    jQuery('#refresh').click(function(e){
        e.preventDefault();
        jQuery.ajax({
            type:'POST',
            url: '2.php',
            data: { variable: '<?php echo $PHPvariable ?>' },
            dataType : 'json',
            success:function(response){
                alert(variable);
            }
        })
    });
</script>

For your better understanding, this script is called from within the 1.php file. As you can see I'm trying to retreive the $PHPvariable variable declared in 2.php. Am I doing it correctly??

This is the varialbe delcaration in 2.php

$PHPvariable = 'bla1bla2bla';
$variable = array('PHPvariable ' => $PHPvariable );
echo json_encode($variable);

What is wrong ??

Answer 1

in 2.php the variable (POST using JS) can be accessed using $_POST['variable']; (in PHP).

sessionVar (JS) in 1.php is undefined (JS), data can be accessed by response.sessionVar (JS) (from success:function(response){).

In 2.php you have to print the data like echo json_encode(array('sessionVar' => $sessionVar)); (PHP).

Update: To prevent confusion I pointed out wether the code parts are PHP or JS.

Update:

You can't expose data and a binary image in a response as there is no multipart response in common HTTP (not sure about SPDY). Either expose an image OR data, not both.

What you can do is to base64 encode the image and output the image as part of the data:

echo json_encode(array(
    'image' => base64_encode($image),
    'variable' => $someVariable),
);

A different approach is not to use ajax but use phps include('2.php'); instead, then the variable is available in 1.php.

Answer 2

For your better understanding, this script is called from within the 1.php file. As you can see I'm trying to retreive the $PHPvariable variable declared in 2.php. Am I doing it correctly??

For passing variable from 1.php and 2.php you have to use the form.

This is a example for the login user

<form action="2.php" method="post">
    <table>
    <tr>
        <td>
            username:
        </td>
        <td>
            <input type="text" name="userName">
        </td>
    </tr>
    <tr>
        <td>
            password:
        </td>
        <td>
            <input type="password" name="password">
        </td>
    </tr>
    <tr>
        <td>
            <input type="submit" name="invio" value="login">
        </td>
    </tr>
    </table>
</form>

Now inside the file 2.php you verification the variable passing.

<?php
ini_set('display_errors', 1);
error_reporting(E_ALL & ~E_NOTICE);

if (isset($_POST['invio']))
    if (empty($_POST['userName']) || empty($_POST['password']))
        $messaggio = "dati mancanti";
    else {
        session_start();
        $_SESSION['userName']  = $_POST['userName'];
        $_SESSION['dataLogin'] = time();
        $_SESSION['ruolo']     = $ruolo[0];

        $messaggio = '<p> <h1 style="color:red">Benvenuto </h1> </p>';


        ;
    }

?>

Now you can print (always inside the page 2.php) the result of message:

<?php
echo $messaggio;
echo $_POST['userName'];
?>

And for return in the page 1.php you can with:

  <?php
header('Location: 1.php');
?>

Inside the script of php.

If you want to use AJAX and without refreshing page I think that you want this exercise

And I suggest for you case this:

var value="your value"
xmlhttp.open("GET","gethint.asp?q="+value,true);

And on gething.php

 <?php
//get the q parameter from URL
 $q=$_GET["q"];

 //lookup all hints from array if length of q>0
 if (strlen($q) > 0)
 {
  echo $q;
}else{
 echo "miss value";
}
?>