Valid JSON or JavaScript object to parse

Question

I have a long polling operation that posts new objects as a JSON just fine, but while getting the updates returning an object, it seems like there is a not-valid JavaScript object I can't parse with jQuery and since it's not valid JavaScript object I can't reach in. Here is console.log I got with the update:

{'body': 'hello world', 'html': '\n<div class="message" id="md1f1cdab-3c3a-4dfe-b268-834aa9981dec"><b>burakdede: </b>hello world</div>\n', 'from': 'burakdede', 'id': 'd1f1cdab-3c3a-4dfe-b268-834aa9981dec'}

Before the response comes out, I am using eval("(" + response + ")") to turn it into a JavaScript object. A show message is used for both posting a new message and getting updates. It works fine with the new posting, but it gives an error when the response comes out.

var updater = {
    errorSleepTime: 500,

    poll: function() {
        var args = {"_xsrf": getCookie("_xsrf")};
        args.listing_id = $(".action").attr("id");

        $.ajax({url: "/a/message/updates", type: "POST", dataType: "text",
                data: $.param(args), success: updater.onSuccess,
                error: updater.onError});
    },

    onSuccess: function(response) {
        try {
            updater.newMessages(eval("(" + response + ")"));
        } catch (e) {
            updater.onError();
            return;
        }
        updater.errorSleepTime = 500;
        window.setTimeout(updater.poll, 0);
    },

    onError: function(response) {
        updater.errorSleepTime *= 2;
        console.log("Poll error; sleeping for", updater.errorSleepTime, "ms");
        window.setTimeout(updater.poll, updater.errorSleepTime);
    },

    newMessages: function(response) {
        if (!response.messages) return;
        var messages = response.messages;
        //console.log(messages.length, "new messages, message is :", messages);
        updater.showMessage(messages);
    },

    showMessage: function(message) {
        var existing = $("#m" + message.id);
        if (existing.length > 0)return;
        var node = $(message.html);
        node.hide();
        $("#inbox").append(node);
        node.slideDown();
    },
};

function newMessage(form) {
    var message = form.formToDict();
    var disabled = form.find("input[type=submit]");
    disabled.disable();

    $.postJSON("/a/message/new", message, function(response) {
        updater.showMessage(response);
        if (message.id) {
            form.parent().remove();
        } else {
            form.find("input[type=text]").val("").select();
            disabled.enable();
        }
    });
}

Rather than fixing on the client side, I fixed the server side code and it is now working. The problem was that it could not produce proper JSON.

What kind of error do you get and where?

FK82
– FK82

2011-12-11 12:55:02 +00:00
Commented Dec 11, 2011 at 12:55 — FK82
– FK82, Commented Dec 11, 2011 at 12:55

Peter Mortensen · Accepted Answer · 2012-06-28 20:07:25Z

1

Specify dataType = 'json' instead of 'text'. jQuery will handle an invalid response for you.

edited Jun 28, 2012 at 20:07

Peter Mortensen

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answered Dec 11, 2011 at 11:04

jcisio

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2 Comments

Burak Dede Over a year ago

you mean poll function cause both of ajax queries have dataType=text ?

jcisio Over a year ago

I mean that why don't use dataType: "json", then the response is an object so that you can use directly response.body, response.html,... And (I think) there is a chance that jQuery handles invalid reponses for you.

Saeed Neamati · Accepted Answer · 2011-12-11 11:03:52Z

0

JSON object properties need to be wrapped inside double-quotes to be valid. Look at the definition of the value in http://json.org.

answered Dec 11, 2011 at 11:03

Saeed Neamati

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3 Comments

Saeed Neamati Over a year ago

Are you generating the JSON? Then simply instead of creating something like {name: 'saeed'} or {age: 23}, etc., create something like {"name": "saeed", "age": "23"}. In other words, wrap all property names and all values with double-quotes. This is the safest way.

Burak Dede Over a year ago

here is python side code for update it just return dictionary object which should be fine <code>self.finish(dict(messages=str(messages.body)))</code>

FK82 Over a year ago

Actually the eval Function should handle that Object literal without a problem. JSON specifies double quotes for keys but this is not required in JavaScript per se.

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