subrecords wwtp_structure not deleted when changing ws_type of wwtp_structure

[urskaufmann]

wwtp_structure records are in vw_tww_wastewater_structure, but have no value in field ws_type. And the two fields of class wwtp_structure are not in the main-view. If I change the subclass of such a record form "empty" to "special_structure", there is just a new record special_structure generated. The old record in class wwtp_structure is not deleted (as writen in the docu and as it is the behaviour with other subclasses). The UI-behaviour is then ok (it shows as special_structure), but in the database, there are to many subrecords. -> that's a BUG.

If I want to change another subclass (e.g. special_structure) into a wwtp, I have now no support from tww/qgep.

There exists the vw_wwtp_structure (is not part of the tww-project-file), that has a polygon-geometry. Imo this vw should have a point-geometry (from the wastewater node, the same way as the vw_tww_wastewater_structure), because in many cases, I have no polygon of a Kleinkläranlage (small wwtp).

The easiest solution would be to add the two wwtp_structure fields in vw_tww_wastewater_structure and to have also wwtp_structure as ws_type. But there are also the new subclasses small_treatment_plant and drainless_toilet, and to join these subclasses also to our main_view seems to be to much.

[sjib]

Discussion on this topic is already opened here: https://github.com/teksi/wastewater/discussions/38

[sjib]

@cymed has already created an extra view for the thre new subclasses drainless_toilet, wwtp_structure and small_treatment_plant are handled separately to not blow up the main ws view. @urskaufmann See https://github.com/teksi/wastewater/pull/42

[urskaufmann]

Sorry for duplicating. Then it's just to correct the case, when changing the ws_type