[Qgis-user] How to use spatial filtering in dataprovider filter

[Luigi Pirelli]

for not spatial enable layers (e.g. without embedded spatial operators)
AFAIK you should use create a qgis virtual layer or an external gdal vrt.

http://www.sigte.udg.edu/jornadassiglibre2016/wp-content/uploads/2016/01/qgis_vlayers.pdf
https://github.com/mhugo/qgis_vlayers/blob/master/README.md

Luigi Pirelli

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On Wed, 10 Apr 2019 at 11:01, Bo Victor Thomsen <bo.victor.thomsen at gmail.com>
wrote:

> Hi all -
>
> Im am experimenting with using the dataprovider based *spatial* filtering
> in QGIS
>
> For example: with a Postgres based datasource I can write a filter like
> this:
>
> ST_Intersects( "geometry", ST_GeomFromText(' Polygon ((582084. 6143051.
> ...... lots of coordinates ... 582084. 6143051.))', 25832))
>
> This will show a layer that only contains objects which actually
> intersects with the text defined polygon even if the unfiltered datasource
> contains a large number of objects taht does not intersect withe the text
> polygon
>
> Something similar can be done with SQLserver to:   mygeom.ST_Intersects
> (...) = 1
>
> But what about ogr file based vector sources like tab or shape files ?
>
> You can define a *alfanumerical* filter like this : "myfield"  > 27  to a
> ogr file datasource. Works like a charm.
>
> But what about *spatial filtering* ? Iv'e tried to use the same expression
> like the postgres  one but on a shapefile. I don't get any errors :-).
> However the filter function doesn't work and let all objects through the
> filter :-(
>
> What am I doing wrong with the file based spatial filtering?  Or is it
> simply impossible ?
>
>
> --
> Med venlig hilsen
>
> Bo Victor Thomsen
>
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