Re: [xml] help: how to get content of an element via XPath in libxml2

[Daniel Veillard <veillard redhat com>]

On Wed, Apr 23, 2003 at 04:49:09PM -0700, andy glew amd com wrote:
> help: how to get content of an element via XPath in libxml2
>
>
> Stupid question, but...
>
> I am using libxml2, 2.5.6
>
> I want to be able to use XPath syntax to get the textual content
> of a field of a record.  E.g. for something like:
>
> <record>
>    <field>value</field>
>    <field1> value1 
>      <baz/> 
>    </field>
> </record>
>
> after having parsed the above, I want to be able to do something like
>
> assert(
>    document.get_by_xpath("/record/field")
>    == "value"
> )
>
> and
>
> assert(
>    document.get_by_xpath("/record/field1")
>    == " value\n     <baz\>\n   "
> )
>
>
> ok, I wrote the above in a C++ style syntax
> - in C it might look like
>
>
> assert(
>    0 == strcmp( xmlGetContent(xmlXPathEvalExpression(document,"/record/field")))
>                 "value" )
> )
>
> (with a memory leak... yeah, yeah...)
>
>
> I must be stupid, or, at least, lacking a good browser,
> but I can't figure out how to go from xmlXPathEvalExpression
> to any of the xmlNodeGetContent or similar functions.

  You understand that xmlXPathEvalExpression(document,"/record/field"))
returns a node set, that a node set may potentially contain 0, 1 or N 
nodes. A nodeset is not a node, you can't xmlGetContent() the result !
  an xmlXPathEvalExpression returns a xmlXPathObjectPtr
  an xmlXPathObject is a structure with a type
  extracting informations depens on the type returned. Could be a string
for example xmlXPathEvalExpression(document,"string(/record/field)"))
but this actually isn't what you want.
  Try to read about XPath, look a the structures for xmlXPathObjectPtr
check the code of xmlXPathDebugDumpObject() in xpath.c to help if
needed. And subscribe to the list if you need more information,

Daniel

-- 
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veillard redhat com  | libxml GNOME XML XSLT toolkit  http://xmlsoft.org/
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