[QGIS-Developer] issues with 1:n relations

[Raymond Nijssen]

Hi Giovanni,

Not sure what you exactly did, I wasn't even aware of QGIS being able 
doing any 1:n relations.

But a few months ago I had to do a more complex 1:n relation, including 
adding some fields. I solved it by using a virtual layer. The 
description is here:

http://www.qgis.nl/2018/02/16/english-diagrams-for-features/?lang=en

Maybe it could help you. Or maybe you know an easier way for doing this? 
Btw, I would normally do this using PostGIS but this was a question from 
a customer.

Ciao,
Raymond


On 17-04-18 18:23, Giovanni Manghi wrote:
> Hi all,
> 
> I have recently had to test some scenario with 1:n relations in QGIS and 
> I have found a few issues and would like to know if someone has them in 
> its pipeline/todo list, eventually to share the effort for the fixes.
> 
> Anyway I'm also interested on your feedback on the matter.
> 
> 1) 1:n relations in QGIS3. They seems unusable at the moment. When 
> opening a parent layer feature form, the area/space where the child 
> records should show does not show/cannot be expanded.
> 
> 
> 2) 1:n relations in QGIS 2.18.
> 
> I have tried a scenario (that to me seems not unusual at all) where both 
> the parent and the child are layers/tables with a geometry.
> 
> The case where the child has its own geometries does not seems well 
> implemented (if implemented at all) in the context of the relation 
> feature form and this causes the following:
> 
> a) from within the parent feature form, if I edit the child and try add 
> a new record there is no tool to allow also add/digitize the proper 
> geometry. The user can still enter only the attributes and when saving I 
> have seen two things happen *) In a test project using GPKGs this led 
> effectively to a record orphaned of its geometry *) In a test project 
> using PostGIS layers the edits are *silently* discarded, no warning, no 
> error, not even in QGIS logs.
> 
> b) from within the parent feature form, when toggling editing for the 
> child, this is effectively put it in edit state also in the layers 
> panel. So a user can "move away" the parent feature form (that it is on 
> first plane) and use the standard editing tools to add a geometry to the 
> child layer. When finished the attributes form pop-up and can be used to 
> fill the data, with the important issue/limitation that the "referencing 
> field" is *not* automatically filled as it is done when working within 
> the relation form. Once saved the new record will also show in the 
> relation form. This seems a partial workaround because as said the 
> referencing field is not automatically filled.
> 
> Am I missing something?
> 
> thanks in advance for your feedback.
> 
> cheers
> 
> -- Giovanni --
> 
> 
> 
> 
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