JQuery Ajax call returns non-json data, but I get a SyntaxError?

Question

Here is a code fragment from a page:

$("#add_new").button().click(function (ui,event) {
    var postdata = {
        "action":"new",
        field_kind_id:2,
        collection_id:null,
        parent_id:null,
        app_struct_id:null,
        member_id:1033,
        app_id:1003,
    };
    $.ajax({
        url: "?",
        type: "POST",
        data: postdata,
        error: function(jqXHR, textStatus, errorThrown) {
            $().toastmessage("showErrorToast",
                "AJAX call failed: "+textStatus+" "+errorThrown);
        },
        success: function(data) {
            edit_record(data);
            return false;
        }
    });
});

Actually the POST-ed data is something like:

action  new
app_id  1003
app_struct_id   null
collection_id   null
field_kind_id   2
member_id   1033
parent_id   null

And the response is this string:

{\x22app_id\x22:1003,\x22member_id\x22:1033,\x22collection_id\x22:\x22-6885\x22,\x22field_kind_id\x22:2,\x22sample_id\x22:\x22\x22,\x22parent_id\x22:\x22\x22}

The response is not valid json data. It has a special format. My problem is that the above ajax call displays this toast message:

"AJAX call failed: parsererror SyntaxError: illegal character"

So it seems that the AJAX call has failed. But I don't understand what is checking the syntax? What kind of syntax? The JQuery Ajax call did not have "dataType:json" specified. So there should not be any syntax to be checked. What am I missing?

The JQuery documentation says the default value for "dataType" is "intelligent"

"Intelligent Guess (xml, json, script, or html)"

If the response cannot be interpreted as a JSON value, then it is not a JSON value, right? Either it is not a valid JSON value (in that case, it should not be converted) or it is (but then it should not throw an exception?) Does it mean that jQuery is not intelligent enough?

Could you show your php code to format the data

muthu
– muthu

2012-07-16 11:49:23 +00:00
Commented Jul 16, 2012 at 11:49 — muthu
– muthu, Commented Jul 16, 2012 at 11:49

user1517378 · Accepted Answer · 2012-07-16 12:17:28Z

2

I suggest you explicitly set the dataType to "text" (see jQuery.ajax), so that jQuery does not need to guess the response's content type:

$.ajax({
    url: "?",
    type: "POST",
    data: postdata,
    dataType: "text", // the type of data that you're expecting back from the server
    error: function(jqXHR, textStatus, errorThrown) {
        $().toastmessage("showErrorToast",
            "AJAX call failed: "+textStatus+" "+errorThrown);
    },
    success: function(data) {
        edit_record(data);
        return false;
    }
});

The reason for the error you encounter is probably the following: jQuery assumes your server's response is in JSON format and tries to parse it.

answered Jul 16, 2012 at 12:17

user1517378

Sign up to request clarification or add additional context in comments.

Comments

codebox · Accepted Answer · 2012-07-16 11:47:16Z

1

What is the value of the Content-Type header in the response from the server? I would expect any guessing that is performed regarding the format of the content to be based on that.

answered Jul 16, 2012 at 11:47

codebox

20.3k10 gold badges70 silver badges81 bronze badges

2 Comments

nagylzs Over a year ago

Yes, that was the problem. It was text/javascript. Thanks.

inf3rno Over a year ago

Is there a way to avoid this "guessing"? In my case there is no content-type header and the script needs plain text.

Collectives™ on Stack Overflow

JQuery Ajax call returns non-json data, but I get a SyntaxError?

2 Answers 2

Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related