cross-posting http://genshi.edgewall.org/ticket/521
While customizing my Trac installation, I ran across a particularly sticky
problem: it does not seem possible to use the contains() xpath function in
genshi in a way that allows conditionally selecting an element based on its
contents.
The particular example are labels in the change history for Trac. These are
inside strong tags, but have no tag metadata to use for the xpath selector,
so matching on the contents of the strong tag is the only way to alter the
ones I want.
The non-working code that I believe should work:
{{{#!html
<!--
Rewrite labels in the change history. This is busted but *should* work The
error I get is:
File
"/usr/lib/python2.6/site-packages/Genshi-0.6-py2.6.egg/genshi/path.py",
line 932, in as_float return float(as_scalar(value))
ValueError?<http://genshi.edgewall.org/wiki/ValueError>:
invalid literal for float(): .
-->
<strong py:match="ul[@class='changes']/li/strong[contains(.,'Reporter')]"
py:attrs="select('@*')">
Champion:
</strong>
}}}
Also tried *text()* instead of *.* in contains(), that also errors out.
Here is the code I finally got to work, after literally hours of screwing
around and research:
{{{#!html
<!--
Rewrite labels in the change history.
-->
<strong py:match="ul[@class='changes']/li/strong"
py:attrs="select('@*')">
<py:with vars="text=select('text()').render();">
<py:choose test="text">
<py:when test="'Owner'">Liaison</py:when> <py:when
test="'Reporter'">Champion</py:when> <py:when
test="'Milestone'">Target</py:when> <py:otherwise>$text</py:otherwise>
</py:choose>
</py:with>
</strong>
}}}
If I hadn't eventually realized that select() is represented as a stream
instead of a string, I never would have gotten this working, either.
Thankfully the documentation at
http://genshi.edgewall.org/wiki/Documentation/0.5.x/streams.html#serializationprovided
me with the render() method so I could finally compare strings in
py:choose.
I'd like to strongly advocate that contains() be fixed to work properly, as
it shouldn't be necessary to jump through all these hoops in order to match
on an element's contents.
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