Bug 66205 – [Qt] REGRESSION: error in synchronous ajax call

• Status: RESOLVED
• Resolution: INVALID
• Component: WebKit Qt

[Sylvain Pointeau]

I made a custom network manager that returns a certain json content.
however the received json from the javascript side is with double quote encoded like "
it is then making the query ajax call to fail.

I have added a reduced test case to demonstrate the issue.

It was working fine with Qt 4.7, but then I migrated to MacOS X lion and I switched to Qt4.8 beta.
I don't know the exact webkit version used by Qt4.8 beta.

[Sylvain Pointeau]

Created attachment 103878 [details]
a reduced test case to demonstrate the issue

a reduced test case to demonstrate the issue, using Qt4.8 beta, a custom network manager that returns a json content is the url is ending by .json

[Ademar Reis]

Created attachment 103922 [details]
testcase (fixed)

[Ademar Reis]

Using the attached testcase, I confirmed the problem exists in QtWebKit-2.2 but not in Qt-4.7 (QtWebKit-2.0).

The problem also happens when using QtWebKit-2.2 with Qt-4.7, so the problem appears to be in QtWebKit and not in QNAM or other part of Qt.

When testing against trunk, I get an assertion error:

$ ./webkit_ajax_json_test_case 
root app "/home/ademar/tmp/bla/webkit_ajax_json_test_case" 
ASSERT: "d->recursive" in file thread/qmutex_linux.cpp, line 112
Aborted (core dumped)

[Ademar Reis]

Just FYI, while investigating this, I found a regression in QNAMs code:
https://bugreports.qt.nokia.com/browse/QTBUG-20970

But it appears to be unrelated to this bug. Will keep investigating.

[Ademar Reis]

(In reply to comment #3)
> When testing against trunk, I get an assertion error:
> 
> $ ./webkit_ajax_json_test_case 
> root app "/home/ademar/tmp/bla/webkit_ajax_json_test_case" 
> ASSERT: "d->recursive" in file thread/qmutex_linux.cpp, line 112
> Aborted (core dumped)

Nevermind, this is because I was running against a QtWebKit built with Qt5. With Qt-4.8, trunk shows the same problem.

[Ademar Reis]

The whole problem is in the QUrl creation in main.cpp. QUrls for local files have to use the static method QUrl::fromLocalFile().

For some bizarre reason, it used to work in Qt-4.7, but when combined with a recent QtWebKit, it breaks. Even worse, in Qt-4.8/QtWebKit-2.2 it has a completely unexpected behavior, which is to pass the PWD to QNAM::createRequest().

I think there are two potential improvements:

1. Improve QNAM to fail in a more expected way if the user tries to use a QUrl which is not complete or useful yet ("just a string").
2. Improve QWebView::load() to fail if it receives an incomplete QUrl like that.

Note that QUrls created this way are still valid (isValid() == true), but have no schema (schema() returns "").

BTW, if you use fromLocalFile() to create your URL, you'll be able to remove a lot of unecessary code from your example. I'll attach a clean version to this bug.

[Ademar Reis]

Created attachment 104232 [details]
original testcase cleaned up and using QUrl::fromLocalFile()

[Sylvain Pointeau]

Hi,

I proposed a test case based on my application.
my application simulates a "web server" by calling the CGI behind.
If it runs with local files, it will not work, and that's why I worked with a fake url "http://localhost.xxx.com/".

I don't understand why it is failing in this case...
please consider that I am obliged to fake the url for POST variables.

would you have an alternative then?

[Ademar Reis]

Created attachment 104856 [details]
original testcase cleaned up (mostly coding style)

[Sylvain Pointeau]

after drilling down in JQuery to see what happened, I discovered that:
the async = true  works and returns status=200
but async = false  returns status = 0.

so you can reproduce the bug with having this simpler code below, you will see the status = 0 but it will work because we are just testing the readystate. JQuery will fail because it tests the status.

function search() {

  var xmlhttp= new XMLHttpRequest();
  xmlhttp.open("GET", "test_json.json",false); // false for async = false
  xmlhttp.onreadystatechange=function() {

    alert( "readyState="+xmlhttp.readyState+" status="+xmlhttp.status);

    if (xmlhttp.readyState==4) {
      var myjson = JSON.parse( xmlhttp.responseText );
      alert( myjson.message );
    }
  }
  xmlhttp.send(null);

  return false;
}

[Ademar Reis]

Changing bug title to reflect the real issue (there's no relation with " at all, the problem is the call failure).

[Ademar Reis]

Sylvain: the problem with your testcase is that it's not reduced enough. Instead of using a custom QNAM and a custom reply, why not query a live server to reproduce the problem?

For example, trying your code with http://search.twitter.com/search.json?q=twitter&result_type=mixed&count=5, it works fine, as far as I could understand.

We need a small testcase that shows the problem is in QtWebKit (to be tested with the QtTestBrowser or a very simple QWebView).

[Sylvain Pointeau]

Hi,

if it is working fine on a live server, it means that it is linked to the custom QNAM and custom Reply.
I saw an answer on the mailing list pointing on the bug 57228

https://bugs.webkit.org/show_bug.cgi?id=57228

would it be the root issue?

[Sylvain Pointeau]

I tested the twitter URL (live server) and it doesn't work.
(async = true or false)

I thought it worked. would it be the cross domaine issue? the symptom are the same: ready state=4 and status=0 but no responseText

[Sylvain Pointeau]

Created attachment 107287 [details]
all above + the twitter search

[Ademar Reis]

(In reply to comment #15)
> Created an attachment (id=107287) [details]
> all above + the twitter search

I'm very busy right now, but just a couple of hints: the best way to get someone to work on it is to have a really minimal test-case showing the problem. Can we reproduce it on a live server, without your custom QNAM and QNetworkReply? Can we not use the jquery.js library?

Remember that the patch won't land unless we add a layout test (where we can't use any of the above). A testcase that fits a bug comment would be perfect. :-)

[Sylvain Pointeau]

Created attachment 107650 [details]
Twitter search using JSONP

using Jquery / JSONP to query twitter, it works.

[Sylvain Pointeau]

I tested on a live application (apache + CGI)
the ajax call with async = false is working.

so the issue is from my opinion in the QNAM

[Sylvain Pointeau]

tested on Qt 4.8 RC and it still doesn't work

[Sylvain Pointeau]

up ...

I just tried 4.8.4 and it still has the issue.
(...very annoying)

[Allan Sandfeld Jensen]

I have just tested and this bug appears to be solved. I can reproduce it with QtWebKit 2.2 (from Qt 4.8), but not with QtWebKit 2.3.

[Jocelyn Turcotte]

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