Undefined index error when sending variable from jquery to php

Question

Adapted from this question: Passing Jquery variable to php within a modal

I have it set up, and it should be working, but I am getting the undefined index error.

Inside a while loop:

print '<li>';
        print '<a class="btn btn-default" data-toggle="modal" data-id='.$row['id'].' data-target=".bs-example-modal-lg"><img src="'.$row["image"].'" /></a><br>';
        print '<a class="btn btn-default" data-toggle="modal" data-id='.$row['id'].' data-target=".bs-example-modal-lg"><h4>'.$row['name'].'</h4></a>';
print '</li>';

All of my jquery, including the ajax code:

 $(document).ready(function() {
            $("body").css("display", "none");
            $("body").fadeIn(1000);
            $("a.transition").click(function(event){
                event.preventDefault();
                linkLocation = this.href;
                $("body").fadeOut(1000, redirectPage);      
            });
            function redirectPage() {
                window.location = linkLocation;
            }
        }); 
$(document).on("click", ".btn", function (e) {
            e.preventDefault();
            alert (id);
            var id = $(this).data('id');
            alert (id);
            $("h4.modal-title").text(id);

            //$($(this).attr('href')).modal('show');    
            $.post('food.php',{id:id},function(data){
                alert(data);
                alert (id) // <--THIS ALERT WORKS TOO
            });
        });

The php:

<?php
        $id = $_POST["id"];
        print '<h4>'.$id.'</h4>'

    ?>

I keep getting an index undefined error on $id = $_POST["id"];.

I cant seem to figure out why, I have adapted my code to so many different ways of doing it, but none of them work.

The first alert shows up, but the second does not. The text does get placed within the <div>, however it does not get sent to the variable. All of this is in one file. I have a feeling my ajax code is missing something.

A Var dump shows:

array (size=0)
   empty

weird, can you try replace var id = $(this).data('id'); into var id = $(this).attr('data-id');. — Norlihazmey Ghazali
– Norlihazmey Ghazali, Commented Apr 27, 2015 at 4:01
@Devon You'd have to use square bracket notation for that obj[id] = id, otherwise yeah, it doesn't take the variable's value into account. — user4698813
– user4698813, Commented Apr 27, 2015 at 4:09
What if you try sending the data as {id: 'test'} just to test it out? And check the parameters being sent in the network tab. — user4698813
– user4698813, Commented Apr 27, 2015 at 4:11

Prakash · Accepted Answer · 2015-04-27 05:12:47Z

0

Use the following php code and try again

<?php
    if( isset( $_POST["id"] ) ) 
        $id = $_POST["id"];
    else
        $id = 'Error: id not exist';
    print '<h4>'.$id.'</h4>';
    die();
?>

answered Apr 27, 2015 at 5:12

Prakash

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3 Comments

user2883071 Over a year ago

It says Error: id not exist

Prakash Over a year ago

I didn't get your code: var id = $(this).data('id'); what do you want from this code ?

user2883071 Over a year ago

So when someone clicks either the image or the name, the id is transferred to the jquery variable id. ( think thats what it means)

shadab · Accepted Answer · 2015-04-27 05:19:40Z

0

you are already assuming data is posted. try if isset

if(isset($_POST['id']))
{
     $id = $_POST["id"];
  echo $id;
    }

answered Apr 27, 2015 at 5:19

shadab

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3 Comments

user2883071 Over a year ago

This also does not return anything

shadab Over a year ago

It does not return anything because no data is getting passed. check this line of code var id = $(this).data('id'); instead try adding var id = $(this).data('data-id');

user2883071 Over a year ago

Makes no difference either

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