241827 - builder.refresh method sometimes leaves blank values when datasource is changed.

Status: NEW

(Core :: XUL, defect)

Description

[Herman Veluwenkamp]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7b) Gecko/20040421
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7b) Gecko/20040421

When calling the builder.refresh method after changing the RDF datasource, the
updated widget has blanks where the updated values should appear. Sounds similar
to bug 68306, but calling builder.rebuild does not alleviate the problem.

Reproducible: Always
Steps to Reproduce:
1. load XUL file that uses RDF datasource and view result
2. change the RDF datasource
3. call builder.refresh on the element and view changes


Actual Results:  
Blank values appear in places where data has changes

Expected Results:  
Display the changes.

Comment 1

[Herman Veluwenkamp]

> When calling the builder.refresh method after changing the RDF datasource, the
> updated widget has blanks where the updated values should appear. Sounds similar
> to bug 68306, but calling builder.rebuild does not alleviate the problem.
> 

Using SetTimeout to call builder.rebuild after 100ms does work however.

Comment 2

[Benjamin Smedberg]

This probably is some bizarre combination with the XUL template code and the
mark+sweep algorithm used in the remote datasource. Does this happen for all
templates, or only dont-build-content templates?

Patches welcome...

Comment 3

[Herman Veluwenkamp]

Attachment: Test case for disappearing values.

Test case for disappearing values. To view load 'bug.xul', then change
'object.rdf' datasource. Hit Refresh button and note that changed value(s) will
be blank in the browser (more often than not, that is.)

Comment 4

[Jan Varga [:janv]]

Refresh() is an asynchronous operation. So calling rebuild() just can't work.
You could use the hacky setTimeout() solution or you could add
nsIRDFXMLSinkObserver to listen for onEndLoad() and call rebuild in this method.

Or ...
change Refresh() to Refresh(boolean aSynch)

Comment 5

[Axel Hecht]

Interesting enough that 
nsXULTemplateBuilder::Refresh
actually calls Rebuild, see
http://lxr.mozilla.org/seamonkey/source/content/xul/templates/src/nsXULTemplateBuilder.cpp#265

Smells like a bug to me.

Do we need an observer method for adding/removing of datasources in composite
datasources?

Comment 6

[Jan Varga [:janv]]

I think this is a dupe of 68306. There's even an analysis in bug 68306.

>Do we need an observer method for adding/removing of datasources in composite
>datasources?

hmm, I don't see a need for it ATM.

Comment 7

[Herman Veluwenkamp]

My understanding (which may be incorrect) is that this feature was added to
moz1.7 to allow remote XUL apps to refresh RDF datasources (no extra security
privileges.) Therefore any solution should work within this context.

Comment 8

[Mark Robson]

I have also seen this problem, I shall be making a work-around.