[Qgis-user] How to digitze points, linestrings, polygons in a single PostGIS geometry-column

[Jürgen E. Fischer]

Hi Astrid,

On Mon, 17. Dec 2012 at 09:22:13 +0100, Astrid Emde wrote:
> in a project I want to handle in one PostgreSQl/PostGIS table different
> geometrytypes (POINT, LINESTRING, POLYGON or even MULTI-objects) in a
> single geometrycolumn.
 
> Then I would like to digitize with QGIS new objects. Is this possible?

You can only have one type of renderer (point, line or polygon), therefore the
layers need to have one type of feature (single and multipart doesn't matter
here).

If you have multiple feature types in one column, QGIS will determine which
feature type is there and offer the existing ones and offer those - a row for
each type.  So you can create multiple layers from one column one for each
existing type.

If you have an empty column without a restricting entry in geometry_columns you
can choose which feature type the new features should have.

The case where you want to add features of a different type to a colum that
already has other features, but isn't restricted to one type, isn't covered
in the GUI yet, I think.   Although it should work later as you could have
added that column with different types, when it was still empty.
 
> I tried with the TYPE GEOMETRYCOLLECTION too, but QGIS seams not to
> support this at all.

Right, also something that is related to QGIS restriction to one renderer.  And
in turn a lot of other stuff assumes that a layer can only have features of one
type - so we would probably break a lot, if we added support for multiple
renderers per layer.



Jürgen

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