XPath search problem 1

[graabein]

Hi,

I'm relatively new to XML and XPath programming. I am working on a program for my record collection with XML and C# .NET. The XPath search for album nodes is the problem.

XML example:

<Albums>
  <Album ID=&quot;10&quot;>
    <Artist>Young, Neil</Artist>
    <Artist>Pearl Jam</Artist>
    <Title>Mirrorball</Title>
    <Year>1995</Year>
  </Album>
  <Album ID=&quot;14&quot;>
    <Artist>Young, Neil</Artist>
    <Title>After The Gold Rush</Title>
    <Label>Reprise</Label>
    <Year>1970</Year>
  </Album>
  <Album ID=&quot;142&quot;>
    <Artist>Pearl Jam</Artist>
    <Title>Ten</Title>
  </Album>
</Albums>

Now I want to write an XPathExpression that selects the following:

1) Search independent of lower/upper case
2) "pearl" search returns both Ten and After The Gold Rush
3) Search title as well
4) Return distinct albums (unique ID)

I have the following C# code that does some of this...

expr = nav.Compile("/Albums/Album[contains(Artist, '" + criteria + "')]";

It does return all Neil Young albums with criteria like "You", but it does not locate the Pearl Jam collaboration on Mirrorball. Pearl Jam-search only returns the Ten album. Some XPath gurus willing to help me out?


graabein

 

[harebrain]

Not a C# user, but as you can see, your XPATH pattern only matches the first Artist element, which doesn't satisfy the contains condition. (Test this by reversing the order of the Artist elements.)

An XPATH solution involves iteration (for-each) or apply-templates. I can't help you with the C# implementation.

 

[jel]

Well I did 1,2, and 4, you can figure out 3 by yourself ;-)

1: use translate() function to convert yournode to lcase (make sure your criteria are lcase to)
contains(translate(.,'ABCDEFGHIJKLMNOPQRSTUVWXYZ','abcdefghicklmnopgrstuvwxyz'), '" + criteria + "')]

2: Look for an album that has any artist that has any etc:
/Albums/Album[Artist[contains etc ]]

4: check if there is a preceding node with the same ID:
[@ID!=preceding::Album/@ID]

All put together makes the mother-of-all-x-path-expressions:
/Albums/Album[Artist[contains(translate(.,'ABCDEFGHIJKLMNOPQRSTUVWXYZ','abcdefghicklmnopgrstuvwxyz'), '" + criteria + "')] and @ID!=preceding::Album/@ID]

 

[graabein]

Thanks jel, that's very nice! Works like a charm!