[Qgis-developer] 'reload' a layer

[Germán Carrillo]

Hi Carson,

have you tried updateFieldMap() from QgsVectorLayer? I've just had a
similar problem with memory layers and it turned out to do the trick.

Regards,

Germán
-----------------------------
[1]
http://qgis.org/api/classQgsVectorLayer.html#ae7777703a20367b66ef0200e972f83d1

2012/5/17 G. Allegri <giohappy at gmail.com>

> You're right Carson. I used it only with a WFS layer, and in fact I see
> that WFS is the only providers that implements it.
> There would be the setDataProvider method on the vector layer but it's
> private...
>
> You've raised an important point, that I took for granted :(
> I fear that in this moment the only solution is remove it and reload it.
> giovanni
>
>
>
> 2012/5/17 Carson Farmer <carson.farmer at gmail.com>
>
>> Hi Giovanni,
>>
>> Thanks for the tip. To answer your question: I am trying to
>> synchronise the layer with the datasource. Having said that, I don't
>> seem to be able to get 'reload' to work. It looks like reload is
>> reimplemented in QgsVectorLayer, which in turns calls the
>> dataProvider's reloadData method, so this may vary by provider type? I
>> tried it with a shapefile and a spatialite layer, and it did not seem
>> to do anything: I deleted several fields from the shapefile and added
>> a field to the spatialite layer in an external program, and these
>> changes were not reflected when I 'reloaded' the layers. Am I missing
>> something here? Perhaps there is something else needed to get the
>> changes to 'show up'?
>>
>> Cheers,
>>
>> Carson
>>
>> On Wed, May 16, 2012 at 4:36 PM, G. Allegri <giohappy at gmail.com> wrote:
>> > Do you mean refresh the rendering or synchronizing the layer with the
>> data
>> > source?
>> > I usually use QgsMapLayer::reload() for the latter, and
>> > QgsMapCanvas::refresh() for the first.
>> >
>> > giovanni
>> >
>> > 2012/5/16 Carson Farmer <carson.farmer at gmail.com>
>> >>
>> >> Hi list, does anyone know of a clever way to (programmatically) reload
>> >> a layer without actually removing it and re-adding it to the layer
>> >> list. Some context: I have a layer that sometimes gets updated by an
>> >> external application, and I want to be able to 'refresh' the layer
>> >> from the Python console to reflect these changes (new features,
>> >> deleted features, new attributes, etc.). I *could* simply load the
>> >> layer again, but I'm hoping there is a more efficient way to do this
>> >> (also I want to keep the current styling, layer order, unique layer
>> >> id, etc).
>> >>
>> >> Any thoughts/ideas? Note: assume we are working with a spatialite layer
>> >> for now.
>> >>
>> >> Carson
>> >>
>> >> --
>> >> Dr. Carson J. Q. Farmer
>> >> Centre for GeoInformatics (CGI)
>> >> School of Geography and Geosciences
>> >> Irvine Building, University of St Andrews
>> >> St Andrews, Fife, KY16 9AL
>> >> Scotland, UK
>> >> _______________________________________________
>> >> Qgis-developer mailing list
>> >> Qgis-developer at lists.osgeo.org
>> >> http://lists.osgeo.org/mailman/listinfo/qgis-developer
>> >
>> >
>>
>>
>>
>> --
>> Dr. Carson J. Q. Farmer
>> Centre for GeoInformatics (CGI)
>> School of Geography and Geosciences
>> Irvine Building, University of St Andrews
>> St Andrews, Fife, KY16 9AL
>> Scotland, UK
>>
>
>
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