CODEWITHSUNDEEP
javascriptphpmysqlajax
Neil_Tinkerer
Neil_Tinkerer

Reputation: 119

Uncaught TypeError Message using Javascript variable as argument for PHP function that initiates mySQL query

I spent most of my day yesterday trying to solve this puzzle so today I've decided to reach out for some help. Before I begin, let me state that I am very aware that JavaScript is client-side and PHP is server-side and I use Ajax successfully for various other things. In this case, I can't find any S/O references that are similar to what I'm trying to accomplish. I would've thought this was very basic but I'm missing something here and could use some direction. Thank you.

In essence, I have a Javascript function that produces a JavaScript variable and then calls a PHP function that initiates a mySQL query (all on the same page). If I "hard-code" the argument in my PHP function call (e.g., sc_bdls = <?php echo Candidates::getBDLs(1000033); ?>;), the function runs perfectly and I receive the expected outcome (an array).

However, if I try and use a JavaScript variable in place of the argument, I receive a "Uncaught TypeError: Cannot read property 'id' of undefined" error. I have tried several iterations without success and I suspect I am missing something basic. Here is my code:

    function tab_pos3(row){
            var sc_id = row.toString();
            var sc_bdls = [];
            $.ajax({
                type: "POST",
                url: '/phpscripts/pass.php',   
                data: {row : row},
                success:(function(data){
                console.log("success");
                alert(data);
                })
            });
            sc_bdls = <?php echo Candidates::getBDLs($uid); ?>;
}

Here is the code from the pass.php file:

if(isset($_POST['row']))
{
    $uid = $_POST['row'];
    echo $uid;
}

Please notice that the console.log("success") and the alert(data) both show that the Ajax POST is working. Any thoughts on what might be going wrong? Thank you.

1st EDIT (comment from Swati)

I tried moving the PHP function call as suggested and then used $UID, $data, data, among others, and I still get the exact same error. Here is the edited code:

$.ajax({
            type: "POST",
            url: '/phpscripts/pass.php',  // 
            data: {row : row},
            success:(function(data){
            console.log("success");
            alert(data);
            <?php $row = $_POST['row'];?>; // I tried this based on something I read.
            sc_bdls = <?php echo Candidates::getBDLs(data); ?>;
            })

The fact that the error doesn't change is gnawing at me. Could the argument be passed but in a format that is not being read right? Is the "TypeError" referring to data type?

Upvotes: 0

Views: 143

Answers (1)

endeavour
endeavour

Reputation: 619

Try moving the sc_bdls = <?php echo Candidates::getBDLs($uid); ?>; to pass.php and read the returned data in ajax success function.

Please note php is executed before the browser sees it. And JS code is called client side.

This is how your function will look like

$.ajax({
        type: "POST",
        url: '/phpscripts/pass.php',  // 
        data: {row : row},
        success:(function(response){
              console.log("success");
              sc_bdls=response; // Just to show that response has the value you need.
              alert(sc_bdls);
        })

The pass.php will look like this

// I prefer using !empty here (unless you are expecting 0 as a valid input.
// This ensure $uid isset and is not empty.
// Also if $uid is supposed to be numeric you may want to add a validation here.

if(isset($_POST['row'])) 
{
    $uid = $_POST['row'];
    $response_array = Candidates::getBDLs($uid); //Your question says you are expecting an array
    echo json_encode($response_array);
}

Upvotes: 1

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