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Re: Entity replacements within attributes for CDATA

• To: xml-dev@l...
• Subject: Re: Entity replacements within attributes for CDATA
• From: "Thomas B. Passin" <tpassin@c...>
• Date: Fri, 26 Mar 2004 17:28:27 -0500
• In-reply-to: <20040326204819.11203.qmail@w...>
• References: <20040326204819.11203.qmail@w...>
• User-agent: Mozilla Thunderbird 0.5 (Windows/20040207)

Cabbar Duzayak wrote:

> I have an XML which is similar to:
> 
> <?xml version="1.0" encoding="UTF-8"?>
> <!DOCTYPE TestData [<!ENTITY var1
> '<![CDATA[testvalue]]>'>]>
> <TestData>
>   <Holder>
>     <MyText
> target="http://www.yahoo.com?aa=&var1;">Text
> Source</MyText>
>   </Holder>
> </TestData>
> 
> When I try to parse this, I am getting an exception: 
> '<' cannot appear in attribute value.
> 
> Looks like parser replaces &var1; with
> "<![CDATA[testvalue]]>", 

As expected.

and since attribute values
> can not have "<" in them, this xml can not be parsed.
> And the problem goes away if I replace the entity
> definition with:
> 
> <!DOCTYPE TestData [<!ENTITY var1 'testvalue'>]>
> 
> However, I have to use CDATA here, 

But you **cannot** use a CDATA section in an attribute value.  A CDATA 
section, legal only in element content, simply signals to the processor 
that characters otherwise considered to be markup are to be treated as 
text.  A CDATA section does not do any escaping.

An entity, however, is a substitution macro, and effectively sticks 
characters into the source.  Wrapping them with a CDATA section doe snot 
escape anything.

>cause I don't know
> what the value of "var1" can be at runtime, and it
> might contain quote characters or any other special
> characters and it will be hard to deal with various
> cases if I don't use CDATA...

Too bad, you have to escape the data before the processor sees it.

Cheers,

Tom P

• References:
  • Entity replacements within attributes for CDATA
    • From: Cabbar Duzayak <dcabbar@y...>

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