Calling a specific function from PHP with Jquery & Ajax

Question

For me this is something new, so I am just researching this and trying to understand it. As you can see in the php script there are 2 functions and I am trying to call a specific one with jquery.

Now if I have one function then I can do it, but when I have 2 or more I am starting to get stuck. I suppose I could do this when I have 2 functions, but as soon as more variables are in play or more functions do I just make massive if statements in my php?

The problem is that when I attach a database to it, I would need to consider all inputs that can happen. How do I specify a specific php function when using jquery & ajax?

//function.php
<?php
    function firstFunction($name)
    {
        echo "Hello - this is the first function";
    }

    function secondFunction($name)
    {
        echo "Now I am calling the second function";
    }

?>

<?php
    $var = $_POST['name'];

    if(isset($var))
    {       
        $getData = firstFunction($var);
    }
    else if(isset($var))
    {
        $getData = secondFunction($var);
    }
    else
    {
        echo "No Result";
    }

?>

//index.html
<div id="calling">This text is going to change></div>

<script>

     $(document).ready(function() {
        $('#calling').load(function() {
        $.ajax({
            cache: false,
            type: "POST",
            url: "function.php",
            data: 'name=myname'
            success: function(msg)
            {
                $('#calling').html((msg));
            }

            }); // Ajax Call
        }); //event handler
    }); //document.ready

</script>

Answer 1

You need to pass a parameter in, either via the data object or via a GET variable on the URL. Either:

url: "function.php?action=functionname"

or:

data: {
    name: 'myname',
    action: 'functionname'
}

Then in PHP, you can access that attribute and handle it:

if(isset($_POST['action']) && function_exists($_POST['action'])) {
    $action = $_POST['action'];
    $var = isset($_POST['name']) ? $_POST['name'] : null;
    $getData = $action($var);
    // do whatever with the result
}

Note: a better idea for security reasons would be to whitelist the available functions that can be called, e.g.:

switch($action) {
    case 'functionOne':
    case 'functionTwo':
    case 'thirdOKFunction':
        break;
    default:
        die('Access denied for this function!');
}

Implementation example:

// PHP:
function foo($arg1) {
    return $arg1 . '123';
}

// ...
echo $action($var);

// jQuery:
data: {
    name: 'bar',
    action: 'foo'
},
success: function(res) {
    console.log(res); // bar123
}