Re: [xsl] copy-of problem...

[Jeni Tennison <jeni@xxxxxxxxxxxxxxxx>]

Dave,

>> As usual, the easiest recourse here is to use DOE (this is what
>> it's designed for):
>> 
>> <xsl:template match="description">
>>   <xsl:value-of select="." disable-output-escaping="yes" />
>> </xsl:template>
>
> Well it works Jeni... but I would like to know just why.
> I've never had to use doe before.

Oh right, sorry -- I thought that you'd heard the explanation so many
times here that it wouldn't need repeating. Is it really not in the
FAQ?

> Is this stopping a 'double' escaping of the entity?

The text within the <description> element is just text. If you have:

  <description>blah &lt;bold>blah&lt;/bold> blah</description>

then the value of the <description> element is the string:

  blah <bold>blah</bold> blah

Note that this is a *string*, not a tree. The XSLT processor can't
recognise escaped markup in text automatically. The '<bold>' is just
the characters '<', 'b', 'o', 'l', 'd', '>' as far as the XSLT
processor is concerned, not a tag.

When an XSLT processor serialises a string as XML (or HTML) then it
escapes any significant characters (e.g. < and &) using the normal
escapes. So if you did:

  <xsl:value-of select="description" />

and you were generating XML or HTML then the XSLT processor would
escape the < characters that it sees in the string value of the
<description> element, and the output that you'd see would be:

  blah &lt;bold>blah&lt;/bold> blah

What disable-output-escaping does is to disable this output escaping
-- it stops the processor from escaping the characters that are
significant in XML. So you'd get:

  blah <bold>blah</bold> blah

in the output. A browser will then recognise the <bold> as a tag and
behave accordingly.

Some processors have a parsing extension function (e.g. check out
saxon:parse()) that would allow you to interpret the text inside the
<description> element as XML, which would then allow you to do:

  <xsl:copy-of select="saxon:parse(description)" />

but note that the content has to be well-formed to do that.

In XSLT 2.0, you should use character maps rather than DOE.

>> Or complain to the feed until they give you XML rather than this
>> hybrid.
>
> It is XML... strictly speaking? But agreed its a mess.

What I meant was that the content of the <description> element is just
text, not XML -- it doesn't have any structure that's recognisable to
an XML parser, but you want it to have.

Cheers,

Jeni

---
Jeni Tennison
http://www.jenitennison.com/


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