PHP not correctly returning JSON for an AJAX call

Question

I have a PHP function that is supposed to return a JSON object to an AJAX call, but instead it is returning a string. Here is the PHP that I am calling from an AJAX call.

<?php
  echo json_encode(array("error", 0, "Success!"));
?>

Here is the AJAX call.

    $.ajax({
        type: "POST",
        url: "../api/login.php",
        data: { id: username, password: password },
        success: function(response) {
            alert( "Data Saved: " + response );
            $("#login_username").val("");
            $("#login_password").val("");
        }
      });

When this function returns, I try to access response in the console, and this is what happens

response
> "["error",0,"Success!"]"
response[0]
> "["

PSL · Accepted Answer · 2013-10-17 02:07:34Z

4

If you are expecting an object then specify the dataType:json in the ajax settings. It will also ensure that if there are any invalid JSON being sent from the server, it gets erred out with parse error. Most probably you don't have a content-type (application/json; charset=utf-8) specified in your response header which lets jquery to determine the mime type itself, so specify the dataType ensure that you get an object or an error back(incase of invalid JSON).

  $.ajax({
    type: "POST",
    dataType:'json'
    url: "../api/login.php",
    data: { id: username, password: password },
    success: function(response) {
        alert( "Data Saved: " + response );
        $("#login_username").val("");
        $("#login_password").val("");
    }
  });

edited Oct 17, 2013 at 2:07

answered Oct 17, 2013 at 2:01

PSL

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1 Comment

Phil Over a year ago

Alternatively, set the correct content type for the response (eg header('Content-type: application/json')) and jQuery will pick this up automatically

Shea · Accepted Answer · 2013-10-17 02:13:09Z

2

Your implementation appears to be using jQuery, or some mock-up of jQuery. If it is not using jQuery, I will be happy to share more solutions to your problem.

Add dataType

 $.ajax({
        dataType: 'json',
        type: "POST",
        url: "../api/login.php",
        data: { id: username, password: password },
        success: function(response) {
            alert( "Data Saved: " + response );
            $("#login_username").val("");
            $("#login_password").val("");
        }
      });

The problem is that, by default, jQuery expects a string.

var foo = "bar";
foo[1] === "a"; // true

Documentation: jQuery.ajax

edited Oct 17, 2013 at 2:13

answered Oct 17, 2013 at 2:00

Shea

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Comments

walu · Accepted Answer · 2013-10-17 02:08:35Z

1

add a param in your ajaxcall

$.ajax({
    type: "POST",
    url: "../api/login.php",
    data: { id: username, password: password },

    dataType: "json" //-< add this param.

    success: function(response) {
        alert( "Data Saved: " + response );
        $("#login_username").val("");
        $("#login_password").val("");
    }
  });

http://api.jquery.com/jQuery.post/

answered Oct 17, 2013 at 2:08

walu

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