Question

I have XML that is composed of container nodes holding various child nodes including other container nodes. Sample XML would look like…

<CONTAINER>
    <SEARCHFOR />
    <ITEM/>
    <ITEM/>
    <ITEM/>
    <ITEM/>
    <ITEM/>
    <CONTAINER>
        <SEARCHFOR />
        <ITEM/>
        <ITEM/>
        <CONTAINER>
            <SEARCHFOR />
            <ITEM id="1" />
            <ITEM/>
            <ITEM/>
            <CONTAINER>
                <ITEM id="2" />
            </CONTAINER>
        </CONTAINER>
    </CONTAINER>
</CONTAINER>

I’d like to find the SEARCHFOR node that is nearest (in scope) to the ITEM having id=2. The SEARCHFOR node can be a preceding-sibling of ITEM or a child of an ancestor CONTAINER node. I have an XPath expression that can locate all SEARCHFOR nodes that are in scope that match the criteria, but I can’t seem to get it to only return the single element that is nearest.

//ITEM[@id="2"]/ancestor::CONTAINER/SEARCHFOR

I am testing in Sketchpath and will be implementing this in Delphi using an XML parser that can handle XPath 2.0 so that syntax is also acceptable. I can do this in code by getting my results and using Delphi to get the one of interest, but if at all possible I really need this to be done within the XPath itself for my implementation. Any help is appreciated.

Thanks,
Michael

Answer 1

Maybe this XPath 2.0 expression answers your question :

(//ITEM[@id='2']/(ancestor::CONTAINER/SEARCHFOR|preceding-sibling::SEARCHFOR))[last()]

It works by building a sequence of elements in document order, then it chooses the last one, which is, given your description, the nearest (if I get you right).