Re: [xml] xmlAddChild & xmlCopyNode - namespace lost

On Wed, Apr 21, 2010 at 04:38:34PM +0200, slyght wrote:
Hi there,

I recently had an issue with xmlAddChild and xmlCopyNode which I solved but
still try to understand.

What I did was creating a new subtree and afterwards inserting it into an
existing tree.
So after creating a new node and some children I inserted it into the
existing tree via:
tmpNodePtr = xmlAddChild(parentNodePtr, xmlCopyNode(newNodePtr, 1));

I used xmlCopyNode because the nodes where newly declared within that
function and I assumed the pointers would be invalid as soon as I leave that

The real issue I had was that the namespace of the new node got lost due to
the copy (tmpNodePtr->ns is NULL). I don't understand why, since I have
given the option "1" which should do a recursive copy including namespaces.

So now that I removed the xmlCopyNode and instead wrote:
xmlAddChild(parentNodePtr, newNodePtr);
everything is fine.

Could someone help me to understand why xmlCopyNode is not working in the
way I assumed?

By the way: The existing tree and the new subtree should have the same
namespace, so maybe there's a more clever way to do what I want?

  namespace references are just pointers on elements or attributes to
the actual namespace declaration higher up in the tree. If you copy and
the namespace is not part of that subtree you're likely to loose it
  My advice is to not build the subtree in isolation and then graft it
to the target but instead always build it in its context, i.e. passing
the target to the subtree creation. There is contextual references from
a subtree like namespaces and entities, and it's best to avoid moving
stuff if you don't understand perfectly all the data structures


Daniel Veillard      | libxml Gnome XML XSLT toolkit
daniel veillard com  | Rpmfind RPM search engine | virtualization library

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