Hi Yury,

This sounds like a very different example - here the original, "source" field is just a hidden field that gets its value from the query string. In that case, I would think the ideal solution would be to use the UrlGetParameters extension, to directly use the query string value:

https://www.mediawiki.org/wiki/Extension:UrlGetParameters

I'm not entirely sure that this would work, because I don't remember which parts of the form syntax let you embed a parser function within them - but if it doesn't work, then getting it to work would seem like the simpler, and better, solution.

-Yaron

On Sun, Sep 30, 2012 at 3:41 PM, Yury Katkov <katkov.juriy@gmail.com> wrote:
Hi Yaron!

My example is surely very silly and synthetic so let's just forget
about the flowers
I'll try to explain the real problem I faced with in a Foresight wiki.

Here is my problem domain. There are several brainstorming sessions
about the forecasts on a distant future, all of them have different
topics. Each of those sessions has various objects as the results of
the brainstorming: future trends, possible technologies that may
appear in the future, possible important events. All these data are
loaded to the wiki using the semantic forms. After the brainstorming
ends, the participants can improve the objects, categorize them and
link them together.

Here for example I have the Trend objects. I want to connect Trends to
the Events and to Technologies but only inside the current
brainstorming session.

The semantic form for Trend will look like that:
<FORM>...
{{{field|session name|hidden|required}}} // the only valid way to
create a trend is using the #formlink  on a Session's page. Formlink
will fill this value with the name of the session

{{{field|related events|values from
query=[[Category::Event]][[session::$1]]|substitute=Trend[session
name] | input type=two listboxes}}}

{{{field|related technologies|values from
query=[[Category::Technology]][[session::$1]]|substitute=Trend[session
name] | input type=two listboxes}}}
...
<END OF FORM>

I can use values from concept but it's a very bad workaround if I have
many sessions.

I hope now the case is more clear.
-----
Yury Katkov