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>

sidenote: In the else case of isset($var), you're passing a null to your secondFunction() — Raptor
– Raptor, Commented Sep 5, 2014 at 1:26
Yeah, but what if there is an if else? Then how would it know what statement to go to? — jwknz
– jwknz, Commented Sep 5, 2014 at 1:27

scrowler · Accepted Answer · 2014-09-05 01:39:11Z

12

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
}

edited Sep 5, 2014 at 1:39

answered Sep 5, 2014 at 1:28

scrowler

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3 Comments

Raptor Over a year ago

IMO, don't use function_exists() on $_POST values. Potential security error / have chance to corrupt the page / server. Imagine the action is fopen , passthru or ini_set...

jwknz Over a year ago

So is action: a keyword for the function name?

scrowler Over a year ago

@JeffKranenburg yes, it's just an example variable name. As Raptor mentioned, calling any function may not be appropriate - so I'd suggest a whitelist instead (will add to answer)

Raptor · Accepted Answer · 2014-09-05 01:29:02Z

4

You are actually quite close to what you want to achieve.

If you want to specify which function will be called in PHP, you can pass a variable to tell PHP. For example, you passed request=save in AJAX, you can write the PHP as follow:

$request = '';
switch(trim($_POST['request'])) {
  case 'save':
    $player_name = (isset($_POST['playername']) ? trim($_POST['player_name']) : 'No Name'));
    saveFunction($player_name);
    break;
  case 'load':
    loadFunction();
    break;
  default:
    // unknown / missing request
}

EDIT: You can even pass along with other parameters

answered Sep 5, 2014 at 1:29

Raptor

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1 Comment

jwknz Over a year ago

Ah I see what you are saying, cool I will have a play with that.

DragonFire · Accepted Answer · 2017-05-01 00:28:19Z

0

This may not be exactly what you are looking for but it can help some others looking for a very simple solution.

In your jquery declare a variable and send it

var count_id = "count";

data:
{
    count_id: count_id
},

Then in your php check if this variable is set

if(isset($_POST['count_id'])) {

Your function here

}

answered May 1, 2017 at 0:28

DragonFire

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