Support for Postgis tables with multiple geometry types with Z

[jgrocha]

Support for Postgis tables with multiple geometry types

When a Postgis table has more than one kind of geometry (Point, LineString, Polygon), DB Manager allow the user to add a layer with just Point features, or with just Polygon features, for example.

That behaviour is illustrated in the following DB Manager dialogue, where we can see three different layers that can be added for the same Potsgis table edificio.

This works well, if the geometry are only 2d.

Describe the bug

If the Postgis table has Z geometry (geometry with 3D), the layers are added to QGIS without the Z component. If the Postgis table has points with Z, lines with Z or polygons with Z, the layers are added, but the Z component is lost.

How to Reproduce

To reproduce this limitation, we need to create a Postgis table with the geometry type with 3 dimensions.

CREATE TABLE public.curso_de_agua_z (
	identificador uuid NOT NULL DEFAULT uuid_generate_v1mc(),
	inicio_objeto timestamp NOT NULL,
	fim_objeto time NULL,
	delimitacao_conhecida bool NOT NULL,
	CONSTRAINT curso_de_agua_z_pkey PRIMARY KEY (identificador)
);

SELECT AddGeometryColumn ('public','curso_de_agua_z','geometria',3763,'GEOMETRY',3);

Add layer to QGIS

The previous table is shown and can be added to QGIS, using DB Manager.

The layer is reported as having 3 dimensions.

Added layer does not have 3 dimensions

After adding the layer, it does not preserve the 3 dimensions.

This can be checked immediately on the layer tree (mouse over the layer with report it as Polygon, not as PolygonZ, for example).

Editing the layer, and showing the vertice editor, the 3 dimension does not appear.

QGIS and OS versions

Tested with 3.8.1-Zanzibar

POSTGIS="2.5.2 r17328" [EXTENSION] PGSQL="110" GEOS="3.7.0-CAPI-1.11.0 673b9939" PROJ="Rel. 5.2.0, September 15th, 2018" GDAL="GDAL 2.3.2, released 2018/09/21" LIBXML="2.9.4" LIBJSON="0.12.1" LIBPROTOBUF="1.3.1" RASTER

Additional context

Support for 3D works, if the Postgis table has only one kind of geometry.