Question

I’m trying to replace the content of a div after clicking on a link using Rails 3, remote_link :remote => true and jQuery.

So far, I’ve been able to get the controller render the correct partial while responding with a 200 HTTP code. I’ve set some callbacks to find the origin of the problem:

jQuery(function($) {
    $("#follow-link").bind("ajax:before", function() {
        console.log("ajax:before");
    });

    $("#follow-link").bind("ajax:success", function(data, status, xhr) {
        console.log("ajax:success");
    });

    $("#follow-link").bind("ajax:complete", function() {
        console.log("ajax:complete");
    });

    $("#follow-link").bind("ajax:error", function(xhr, status, error) {
        console.log("ajax:error");
        console.log(error);
    });
});

While before and complete are triggered, success is not and error outputs “parsererror”. The content I get when I inspect the response in Safari’s developers tools is a simple string.

Why would it raise a parsererror? How can I get more information about what’s causing this error?

Answer 1

I’m going to propose an answer because comments don’t allow for any formatting. Here is is: Something is happening on the server side and jQuery is not getting what you think it is. Here’s an excerpt from the jQuery documentation:

error(jqXHR, textStatus,
errorThrown)Function A function to be
called if the request fails. The
function receives three arguments: The
jqXHR (in jQuery 1.4.x,
XMLHttpRequest) object, a string
describing the type of error that
occurred and an optional exception
object, if one occurred. Possible
values for the second argument
(besides null) are “timeout”, “error”,
“abort”, and “parsererror”. When an
HTTP error occurs, errorThrown
receives the textual portion of the
HTTP status, such as “Not Found” or
“Internal Server Error.”

That implies that your controller may be responding with something other than the expected data. In that controller, try:

Rails.logger.debug render_to_string(:partial => "followings/follow")

In any case, check your logs to make sure what you think is happening really is happening. Also, write a test to verify this:

# controller spec... modify if using Test::Unit
it "sends cool javascript" do
  xhr.post :unfollow, :id => 83, :data-method => "delete"
  response.body should == "some known response"
end

Ok, it’s a hacky, brittle spec, but it will do until you know where things are going wrong.

Once you get this working, everything else will fall neatly into place.