QGIS » QGIS Application

In QGIS master and the release-3_4 branch, adding a custom UI with a list widget (value relation) pointing to an array column in Postgresql doesn't work anymore.
I don't see the List widget cannot be editable.

On the left side of the below picture is the currently look versus the 2.18 on the right side:

I tried using a QgsCheckableComboBox and although I can see the workers and select them QGIS tries to save the last selected one as an integer and it doesn't work (as I have an array of integers in the column).
You can bypass this by writing code but I would have expected that a custom UI just worked for this case.

I've attached a test project.
Step 1, create the tables:

CREATE DATABASE bugtest;
\c bugtest;
CREATE TABLE work_planning (id serial PRIMARY KEY, fk_workers integer[]);
CREATE TABLE workers (id serial PRIMARY KEY, worker varchar(100));
INSERT INTO workers (worker) SELECT 'worker 1';
INSERT INTO workers (worker) SELECT 'worker 2';
INSERT INTO workers (worker) SELECT 'worker 3';
INSERT INTO workers (worker) SELECT 'worker 4';

Step 2, open the bugtest.qgs project with Master or Madeira and try to add a new work_planning feature:

It doesn't work.
It works on the bugtest2.18.qgs if you open it in 2.18.

The widget settings: