XPath question.
in [Java Programming]
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From: Mike Schilling on 15 Mar 2010 15:44 Daniel Pitts wrote: > On 3/15/2010 11:25 AM, Mike Schilling wrote: >> Daniel Pitts wrote: >>> On 3/13/2010 6:13 PM, Mike Schilling wrote: >>>> Daniel Pitts wrote: >>>>> On 3/12/2010 8:31 PM, Mike Schilling wrote: >>>>>> Daniel Pitts wrote: >>>>>>> On 3/12/2010 2:56 PM, Daniel Pitts wrote: >>>>>>>> I have a document which has two elements: ValueOverride and >>>>>>>> ValueDefault For example: >>>>>>>> <MyDoc> >>>>>>>> <ValueOverride>The override value</ValueOverride> >>>>>>>> <ValueDefault>The default value</ValueDefault> >>>>>>>> </MyDoc> >>>>>>>> >>>>>>>> I need a single XPath expression that will return ValueOverride >>>>>>>> if it is non-empty, and ValueDefault otherwise. >>>>>>>> >>>>>>>> Is this possible to do with XPath? >>>>>>>> >>>>>>>> Thanks, >>>>>>>> Daniel. >>>>>>>> >>>>>>> Figured it out: >>>>>>> ./ValueOverride|./ValueDefault[../ValueOverride=''] >>>>>> >>>>>> What do you mean by "non-empty'? If you mean "has no text nodes >>>>>> for children", that expression doesn't work for the document >>>>>> >>>>>> <MyDoc> >>>>>> <ValueOverride/> >>>>>> <ValueDefault>The default value</ValueDefault> >>>>>> </MyDoc> >>>>>> >>>>>> It returns two nodes, the elements ValueOverride.and >>>>>> ValueDefault. I'm guessing that what you want is the string whose >>>>>> parent is >>>>>> ValueOverride, if there is one, and if not, the string whose >>>>>> parent is ValueDefault. In that case, try >>>>>> >>>>>> string(./ValueOverride[count(./text())> 0]|./ValueDefault) >>>>>> This uses the fact that string(), like the other conversion >>>>>> functions, when applied to a node-set ignores any nodes after the >>>>>> first. >>>>> Strange, the solution I posted worked just fine for me. >>>> >>>> Then you must not have applied it to >>>> >>>> <MyDoc> >>>> <ValueOverride/> >>>> <ValueDefault>The default value</ValueDefault> >>>> </MyDoc> >>>> >>>> And perhaps that's not a document you need to apply it to. It was >>>> difficult to tell from the description of the problem. >>> Are you saying that<ValueOverride></ValueOverride> will have a >>> different value than<ValueOverride/>? >> >> No, they're identical. But if you have either one of them, it'll >> match your XPath expression, even though it doesn't specify a value >> (or, to be more precise, doesn't have any child nodes that are text.) >> >> > So the result will be "The default value", which is what I want. Or > are you saying it is document order-dependent? As I said to begin with, applying ../ValueOverride|./ValueDefault[../ValueOverride=''] to <MyDoc> <ValueOverride/> <ValueDefault>The default value</ValueDefault> </MyDoc> or, equivalently, <MyDoc> <ValueOverride></ValueOverride> <ValueDefault>The default value</ValueDefault> </MyDoc> returns a node set with two nodes: the element ValueOverride and the element ValueDefault (in document order). If that works for you, fine. |