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

[Bo Victor Thomsen]

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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