Re: [bdbxml] Replacing and inserting nodes

> while searching for a free XML database for my diploma thesis, I  
> came across
> bdbxml, which I like a lot. However I am missing a certain  
> behaviour with
> respect to updating and creating nodes in a document.
>
> I am using the Java API and the class in question is of course  
> XmlModify. What
> I need to do is the following:
>
> In a document, locate a specific node and then replace that node  
> with content
> I have as a String. For example I have the following document:
>
> <foo>
>     <bar value="1">
>         data
>     </bar>
>     <bar value="2">
>         moredata
>     </bar>
> </foo>
>
> Now I want to replace the node specified by the XPath
> Query /foo/bar[@value="1"] with the following node:
>
> <bar value="15">
>     randomdata
> </bar>
>
> It seems that there is no method of XmlModify which elegantly  
> handles such a
> situation. It only allows for modification of node contens with
> addUpdateStep. Even the insert methods are not satisfactory for  
> that example,
> because they can't take the whole String as a new node, but require  
> creation
> of an additional node by specifying name and node Type.
>
> Am I missing somethig or do I really need to do something like this:

The former :-)

XmlModify works by adding "steps," and then executing the object.
Each step takes an XmlQueryExpression along with some step-specific
parameters.

In your case, you simply need 2 update steps, one that targets the  
element
to change the content from "data" to "randomdata" and one to
change the attribute, "value" from "1" to "15".

The pseudo-code is along these lines:
     XmlQueryExpression qe1 = mgr.prepare("/foo/bar[@value='1']", qc);
     XmlQueryExpression qe2 = mgr.prepare("/foo/bar[@value='1']/ 
@value", qc);

     XmlModify mod = mgr.createModify();
     mod.addUpdateStep(qe1, "randomdata");
     mod.addUpdateStep(qe2, "15");
     mod.execute(...)

Regards,

George

>
> 1) Strip the root from the string to insert
> 2) insert a new node, with type = element, name = name of the  
> stripped node
> and content of the remaining insert string
> 3) remove the node I wanted to replace.
>
> I hope my explanations are not too confusing ;-)
>
> Regards,
> Sebastian
>


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