Robert Murphy wrote:
> Dear Developers,
>
> I run a wiki with a vast amount of N-ary data. I have yet to hear
> from anyone who has successfully figured out how to query N-ary data.
> Some of you may have seen my many question on the User Mailing List,
> but no has ever said anything other than "I hear someone somewhere at
> sometime solved that with templates." I have not been able to solve
> it with templates and no semantic mediawiki I've found has either.
> I'm afraid no one has seriously considered the possibility that N-ary
> data is inaccessible from with Mediawiki.
>
> Basically, if you do pass a query to templates, and one of the
> parameters is N-ary, then a comma separated list of all fields is
> passed and there seems to be no way to handle that data from within a
> template, even if there's only one instances of the n-ary value. If I
> were just within Perl of PHP, splitting on regex's the passed N-ary
> data would be a piece of cake. However, such programming language
> features as "split" and arrays are not possible within a template. I
> think this problem warrants serious developer attention.
I've been thinking about this, and I think that both N-aries and queries
need some refinement, and soon.
On the N-ary front, I'd recommend introducing field names so that individual
fields can be referenced. The simplest way to do this would be to allow
"name=value" pairs anywhere that an N-ary currently permits a value. (Note:
"allow"; not "require". This allows for full backward compatibility.) One
application of the "field name" concept would be the ability to use
something like '[[Property::field=+]]' in a query to find only those pages
where Property has 'field' as a field; or '?Property::field' to include the
value of Property's field in the output.
On the querying front, I think we need something akin to SQL's 'FROM'
clause. Right now, it's assumed that the query is always looking for pages
that match the given criteria; the new feature would allow you to specify
that you're looking for every instance of a given property where the
criteria are satisfied. This would be ideally suited for N-ary properties,
but might be useful elsewhere.
Here's what I envision:
on Page [[N-ary]]:
[[Contributer::Robert Murphy, [EMAIL PROTECTED]
on Page [[Property:Contributor]]:
[[type of::text, email=text]]
on some other page:
{{ask: [[Contributer::email=+]] | ?Contributer::email }}
this would produce something like:
{|
| [[N-ary]] || [EMAIL PROTECTED]
|}
I'd like to implement this myself; but I'm having some difficulty puzzling
out how the code for the N-ary type works. Any advice would be
appreciated.
--
Jonathan "Dataweaver" Lang
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