[Qgis-user] How to get a new 'the_geom' into the 'Init function' of an 'Edit UI'?

[Knut Sübert]

Hello,

using a PostGIS-layer, I thought about adding informations to the
table. 'Edit UI' and 'Init function' are working well for updating
existent geometries. Minimal example:

    def onDialogAcceptClicked(self):

        if self.id: # existing polygon

            query = ("update tablename set "
                     "comment = 'EDIT' " # just an example
                     "where id = %s ") % (self.id)
            self.query.exec_(query)
            
        else: # new polygon

            query = ("insert into tablename (comment) "
                     "values ('NEW') ") # another example
            self.query.exec_(query)

        self.dialog.close()

        return

Database works as expected. A new row with comment 'NEW' is inserted
after creating a new polygon. 

But the column 'the_geom' is empty and the new created polygon
disappears from the map.

Question: How to get the data to set 'the_geom' in case of a new
polygon?

As the 'init function' gets the string 'layerid', which contains the
database connection and the name of the geometry column, maybe there's
a 'magic' function, which has to be be called?

I searched the sources to get the default 'init function', but I
didn't found it.

Regards
Knut