Hi,
> Date: Sun, 10 Jun 2012 11:44:40 +0200
> From: "Lene Fischer"
> To:
> Subject: [Qgis-user] Areaunits and update fiels
> Message-ID: <4fd488a8022e0003d...@gwmta2.kvl.dk>
> Content-Type: text/plain; charset="utf-8"
>
> Hi
>
> I?ve been searching for at setting to set areaunits. We mostly use
> hectare, so the standard alwas has to be divided with 1.
>
> Next question: In the fieldcalculator we can calculate an area, but the
> field isn?t updatet after editing. And suggestions?
>
> Kind Regards
>
>
> Lene Fischer
> Ass. Professor - GIS & GPS
I don't think this is possible at the moment.
There has been some work on adding Python functionality that is similar to the
way VBA is used in Microsoft office - e.g. allowing the use of scripts which
will run automatically when a project is opened or saved. See
http://osgeo-org.1560.n6.nabble.com/Python-support-in-project-file-td4976475.html
I guess the ability to run a script automatically when a feature in a
particular layer is edited would be a nice enhancement to go along with that,
and could be used to achieve what you want.
But I don't think it is good practice to store derived data like this in an
attribute field. And if you are using it for labelling, it will be unnecessary
with QGIS 1.8, which has on-the-fly expression based labelling. Do you really
need it in the attribute table? There was a discussion about implementing
"virtual columns" using the same engine as the expression based labelling. See
http://lists.osgeo.org/pipermail/qgis-developer/2011-July/015383.html
You might want to look at helping implement one of these features.
Regards,
Alister
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