composition relations: only the first relation is taken into account

[Meibes]

What is the bug or the crash?

Hello,

I tried to use composition relations in my project using QGIS 3.34 and PostgreSQL 15 tables but it didn't work

my setup: several postgres tables, one with geometries, several others without, referencing the table with the geometries via foreign keys

my observation: for multiple composition relationships referencing the same parent, only the first composition is taken into account when duplicating/deleting an object from the parent layer.

2024-01-19_10-51-23_qgis_bug_report.mp4

in 3.28 compositions don't work at all
the nightly-dev build behaves exactly like 3.34

@nirvn could you take a look at it? it seems like you worked on compositions in the past #53965

Cheers

Steps to reproduce the issue

1. create the following database:

CREATE EXTENSION IF NOT EXISTS "postgis";

CREATE TABLE IF NOT EXISTS parent(
  id integer PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
  geom geometry(LineString, 4326) NOT NULL,
  description text
);

CREATE TABLE IF NOT EXISTS child_1(
  id integer PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
  parent_id integer REFERENCES parent(id) ON DELETE CASCADE ON UPDATE CASCADE,
  description text
);

CREATE TABLE IF NOT EXISTS child_2(
  id integer PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
  parent_id integer REFERENCES parent(id) ON DELETE CASCADE ON UPDATE CASCADE,
  description text
);

CREATE TABLE IF NOT EXISTS child_3(
  id integer PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
  parent_id integer REFERENCES parent(id) ON DELETE CASCADE ON UPDATE CASCADE,
  description text
);

INSERT INTO parent (geom, description) VALUES ('LINESTRING(20.735 42.2126, 20.736 42.2127)', 'parent 1');
INSERT INTO parent (geom, description) VALUES ('LINESTRING(20.736 42.2127, 20.737 42.2128)', 'parent 2');
INSERT INTO parent (geom, description) VALUES ('LINESTRING(20.737 42.2128, 20.738 42.2129)', 'parent 3');

INSERT INTO child_1 (parent_id, description) VALUES (1, 'child 1');
INSERT INTO child_1 (parent_id, description) VALUES (2, 'child 2');
INSERT INTO child_1 (parent_id, description) VALUES (2, 'child 3');
INSERT INTO child_1 (parent_id, description) VALUES (3, 'child 4');
INSERT INTO child_1 (parent_id, description) VALUES (3, 'child 5');
INSERT INTO child_1 (parent_id, description) VALUES (3, 'child 6');

INSERT INTO child_2 (parent_id, description) VALUES (1, 'child a');
INSERT INTO child_2 (parent_id, description) VALUES (2, 'child b');
INSERT INTO child_2 (parent_id, description) VALUES (2, 'child c');
INSERT INTO child_2 (parent_id, description) VALUES (3, 'child d');
INSERT INTO child_2 (parent_id, description) VALUES (3, 'child e');
INSERT INTO child_2 (parent_id, description) VALUES (3, 'child f');

INSERT INTO child_3 (parent_id, description) VALUES (1, 'child i');
INSERT INTO child_3 (parent_id, description) VALUES (2, 'child ii');
INSERT INTO child_3 (parent_id, description) VALUES (2, 'child iii');
INSERT INTO child_3 (parent_id, description) VALUES (3, 'child iv');
INSERT INTO child_3 (parent_id, description) VALUES (3, 'child v');
INSERT INTO child_3 (parent_id, description) VALUES (3, 'child vi');

1. start qgis
2. load all layers from postgres
3. Project -> Properties...
4. Relations -> Add Relation
5. relationship strength -> composition
6. parent -> layer: parent field: id
7. child -> layer: child_1 field: parent_id
8. same procedure for child_2 and child_3
9. set layer parent active
10. toggle editing mode
11. select existing feature(s)
12. edit -> copy features
13. edit -> paste features
14. check notification / editing modes / attribute tables

Versions

QGIS version	3.34.2-Prizren	QGIS code revision	7d19979
Qt version	5.15.3
Python version	3.9.5
Compiled against GDAL/OGR	3.8.2	Running against GDAL/OGR	3.8.3
PROJ version	9.3.1
EPSG Registry database version	v10.098 (2023-11-24)
GEOS version	3.12.1-CAPI-1.18.1
SQLite version	3.41.1
PDAL version	2.6.0
PostgreSQL client version	15.2
SpatiaLite version	5.1.0
QWT version	6.1.6
QScintilla2 version	2.13.4
OS version	Windows 10 Version 2009
Active Python plugins
alkisplugin	2.0.54
firstaid	3.0.3
gewaesserschau-main	0.1
gueasy_plugin	0.1
inspireatomclient	0.8.1
linking_relation_editor	v1.2.0
nominatim_locator_filter	0.3.2
qfieldsync	v4.7.0
volume_calculation_tool	0.4
db_manager	0.1.20
grassprovider	2.12.99
processing	2.12.99

Supported QGIS version

• I'm running a supported QGIS version according to the roadmap.

New profile

• I tried with a new QGIS profile

Additional context

No response