[Qgis-developer] Updating field with a trigger

[Matthias Kuhn]

On 09/10/2015 10:15 AM, Yves Jacolin wrote:
> On Thursday, September 10, 2015 9:36:31 Bernhard Ströbl wrote:
>> Hi Yves,
>>
>> Am 10.09.2015 um 09:27 schrieb Yves Jacolin:
>> [..]
>>>> Apart from that if
>>>> field#2 = field#1 + x
>>>> then field#2 is totally redundant. You could either create a view
>>>> containing this field or create a virtual field in QGIS.
>>> I just simplified for the test case. This is more complicated but was not
>>> useful to give such details ;)
>> still this should be considered an option to show the resulting value to
>> the user instead of having it in a field of its own.
> Humm, I need to think a little bit on this. I am not sure that move some logic 
> from the db to QGIS is always a good things. 
>
> One of the use case which lead me to let this logic in the DB is when I use 
> this field in several part (for example, in a layer in QGIS and in a website, 
> for an export with ogr2ogr or event in several layers in QGIS). 
A view would be perfectly suitable for this.
>
> It is easier to manage one location (ie the trigger) than several (in QGIS if 
> we use this field in different layer). I need to check this but we are in such 
> use case.
>
> Anyway, I agree with you in other use case that it is easier to manage this as 
> a virtual field, much less trouble :)
You could hide the field from the view and add a virtual field in QGIS
that does the same calculation, that's probably easier than python

M.
>
> Y.
> _______________________________________________
> Qgis-developer mailing list
> Qgis-developer at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/qgis-developer


-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: OpenPGP digital signature
URL: <http://lists.osgeo.org/pipermail/qgis-developer/attachments/20150910/c69e0cf5/attachment.pgp>