[PATCH] Plugin breaks stream for subsequent plugins

[Cinc-th]

The line

...
html_stream = HTML(stream)
...

in filter_stream() prevents subsequent plugins from adding stylesheets using add_stylesheet(). As soon as one uses HTML() on a stream this happens. I didn't find the cause for that.

For testing just insert add_stylesheet(req, "foo.css"):

    def filter_stream(self, req, method, filename, stream, data):

        if req.path_info.startswith('/admin/ticket/components/'):
            trans = Transformer('//form[@id="modcomp"]/fieldset/div[1]')
            stream = stream | trans.after(self._parent_component_select(req, data)) 

        elif req.path_info.startswith('/admin/ticket/components'):
            # add a "parent component" column to the components table
            stream = stream | Transformer('//table[@id="complist"]/thead/tr/th[3]').after(tag.th("Parent"))

            html_stream = HTML(stream)
            # Try adding a stylesheet here
            add_stylesheet(req, "foo.css")
            html_comp_list = HTML(html_stream.select('//table[@id="complist"]/tbody'))
            
            return html_stream | Transformer('//table[@id="complist"]/tbody').replace(self._insert_parent_column(html_comp_list))
                            
        return stream

You'll notice that foo.css isn't included as a link in the web page delivered by Trac (use the developer tools of your browser, or just look at the head section of the page source).

I suspect the stream is altered in a way that Trac can't inject the link when preparing the page. I noticed that this statement causes XML namespace information to vanish from tag data in the stream when fixing a compatibility problem with SimpleMultiProjectPlugin, see #12367, [14639].

The attached patch uses another method to insert the parent column into the table. This fixes this problem for me.

[Cinc-th]

Patch for adding parent column using injector transformation.

[Cinc-th]

File admin.py with patch applied.

[falkb]

Thanks! Seems to work properly. Lets see what the activities in sibling ticket #12367 will still bring, and if they may change this patch again...

[Cinc-th]

Revised patch which inserts a parent column even for components without a name. Should finally fix #12367, too.

[Cinc-th]

Revised patch which inserts a parent column even for components without a name.

[Cinc-th]

Add the correct CSS class to empty table cells, too

[falkb]

Thanks! Could you attach the whole .py file, please? I'm doing this in parallel to other urgent things, so it would ease things here :)

[falkb]

Yeah, in combination with [14640] of SimpleMultiProjectPlugin, it works properly now with admin-3.diff. Many thanks!!

[falkb]

In 14642:

see #12385: no mixed up columns on Admin->components page anymore for the case when SimpleMultiProjectPlugin also injects a new column into the HTML stream (Thanks to Cinc-th!)

[falkb]

Tested and great.