How can I acheive this logic?

OnDistantShores · February 25th, 2010, 06:41 PM

I'm a relative newbie to XSL. I want to do some logic in XSL that's super easy in any other language, but I just can't seem to find a way to do it in XSL. Please help!

I want to make a template that retrieves a field value in a certain translation. I have a list of available translations. A caller can pass into a template which field they want the value of, along with a list of languages in preference order. The template should then go through the list of languages in order, and when the template finds that that translation exists, it returns that value and stops looking.

At first I thought easy - I'll just do a for each loop and then break after I find a language. But no, Google tells me that XSL processes things in parallel (well, at least non-procedurally), so there's no such thing as a break in XSL.

Then I thought no problem - I'll just create a variable called 'found' or something, set it to false at first, make the loop ensure that it's false, then set it to true when I match a language. But no, Google tells me that XSL is a declarative language, and a variable always has the same value within a given scope. (Hmm, not much of a 'variable' in my opinion, but I digress)

So...how can I do this in XSL? Surely this is possible somehow.

mhkay · February 25th, 2010, 08:21 PM

You need to stop thinking that you have to tell the computer what to do and in what order to do it. In XSLT, you just have to describe your transformation.

Typically, if you want to find the first language that's present in some supplied list of languages, all you need to write is

$languages/language[. = $requiredLanguages][1]

No need to write a loop or break out of it: just tell it you want the first matching language.

OnDistantShores · February 25th, 2010, 10:24 PM

Thankyou very much for your response mhkay.

Unfortunately I don't really understand the solution you're describing. Maybe it would be clearer if I were more specific.

I have an array of languages that looks like:

Code:

<lang>
  <value>fr-fr</value>
  <value>es-es</value>
  <value>en-gb</value>
</lang>

which I'm storing in a variable called $lang.

I then have the data object which looks like:

Code:

<data>
  <id>1</id>
  <priority>0</priority>
  <Translation>
    <en-gb>
      <id>1</id>
      <title>Hello</title>
      <lang>en-gb</lang>
    </en-gb>
    <es-es>
      <id>1</id>
      <title>Hola</title>
      <lang>es-es</lang>
    </es-es>
  </Translation>
</data>

How can I write a single XPath query to get the first available translation from the Translation node which matches languages in order from $lang, retrieve the title, and only get the first one?

Thanks again!

mhkay · February 26th, 2010, 04:16 AM

>Maybe it would be clearer if I were more specific.

It certainly would. Your question was phrased in such vague terms I had no choice but to be vague in my answer.

I don't think that putting data in element names is a particularly good idea, but that's incidental.

The translations which match a value from $lang are /data/Translation/*[lang=$lang//value].

The first such translation is (/data/Translation/*[lang=$lang//value])[1].

The title of this translation is (/data/Translation/*[lang=$lang//value])[1]/title

You don't even need any XSLT code for this - it's just one XPath expression!