Using jquery to parse items from a JSON response

Question

I am using PHP and Ajax to parse some JSON. The PHP is creating the array like this.

$myObj->pid = $_POST["parentid"];
$myObj->comp = $comp;
$myObj->colour = $statuscolour;
$myJSON = json_encode($myObj);
header('Content-Type: application/json');
echo $myJSON;

I use the following jquery code

$.ajax({
        type: "POST",
        dataType: "json",
        url: "msstatup.php",
        data: data
    }).done(function(msg) {
    var response = jQuery.parseJSON(JSON.stringify(msg));
    console.log(response);
    pid = response[0].pid;
    console.log('id = ' + pid);
    });

I can see the output from the first console.log as

Object {pid: "p1", comp: 20, colour: "red"}

However I cannot extract the individual variables, it gives the message

Uncaught TypeError: Cannot read property 'pid'

How can I extract the variable?

Since you're returning JSON you do not have to use parseJSON. — Jay Blanchard
– Jay Blanchard, Commented Feb 13, 2017 at 17:31
Why are you first stringifying then parsing the JSON response? — Sarah Groß
– Sarah Groß, Commented Feb 13, 2017 at 17:32
You seem to be treating the response as an array when it is a single object. Try console.log(response.pid) — Andy
– Andy, Commented Feb 13, 2017 at 17:33

AmericanUmlaut · Accepted Answer · 2017-02-13 17:36:20Z

4

You've made this more complicated than it needs to be. msg is already an object, which you then convert to a string and back to an object with stringify and parseJSON. And then you try to use it like an array, when it is an object.

Try this:

$.ajax({
    type: "POST",
    dataType: "json",
    url: "msstatup.php",
    data: data
}).done(function(msg) {
    var pid = msg.pid;
    console.log('id = ' + pid);
});

answered Feb 13, 2017 at 17:36

AmericanUmlaut

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Comments

charlietfl · Accepted Answer · 2017-02-13 17:36:12Z

2

You are returning an object, not an array.

Also it makes no sense to stringify the data object and parse that string back to object again

Try

var pid = msg.pid;
console.log('id = ' + pid);

answered Feb 13, 2017 at 17:36

charlietfl

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Comments

Sarah Groß · Accepted Answer · 2017-02-13 17:37:26Z

0

First of all, it can't imagine why it would be neccessary to first stringify, then parse the JSON response.

Second, you are trying to access response[0] as if it were an array, which it isn't. You can simply use

response.pid;

To access the object key.

As you don't need to stringify then parse the response, you can just access msg directly, so it all comes down to

$.ajax({
    type: "POST",
    dataType: "json",
    url: "msstatup.php",
    data: data
}).done(function(msg) {
    console.log(msg.pid);
});

edited Feb 13, 2017 at 17:37

answered Feb 13, 2017 at 17:34

Sarah Groß

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6 Comments

Jay Blanchard Over a year ago

msg.pid There is no need for the whole line of code defining response.

Jay Blanchard Over a year ago

I did not DV. But, if I were that guy I would have DV'd because the original end result was not correct or at least compensating for the line of code defining response

Sarah Groß Over a year ago

You mean the typo I had in the very first save of my answer (still leaving the [0]), that I corrected within seconds of posting?

Jay Blanchard Over a year ago

No, response.pid. While correct technically it supported the over-complication of the code.

Sarah Groß Over a year ago

It still was a correct answer that maybe could have used some further tweaking. Imho that's a reason to upvote other answers that cover this better, not downvote an answer. Otherwise, where do we the line of uncovered code optimisations?

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