QGIS expression builder can not resolve PostgreSQL text arrays correctly

[eurojam]

What is the bug or the crash?

I have a PostGIS layer which contains text arrays. At the moment it is not possible to use field values resolved by the expression builder. If the array contains only one item, the field value will be ok, having two or more values within the array, the field value preview returns an empty string

g.

Steps to reproduce the issue

1. load postgis layer containing text array fields
2. select by expression
3. fields and values
4. values->all unique->only show values in use
5. select entry with two or more values in the array
6. returns an empty string/array

Versions

<style type="text/css"> p, li { white-space: pre-wrap; } </style>

QGIS-Version	3.20.3-Odense	QGIS-Codeversion	495fbae
Qt-Version	5.15.2
Python-Version	3.9.5
GDAL-Version	3.3.1
PROJ-Version	8.1.1
EPSG-Registraturdatenbankversion	v10.028 (2021-07-07)
GEOS-Version	3.9.1-CAPI-1.14.2
SQLite-Version	3.35.2
PDAL-Versio	2.3.0
PostgreSQL-Client-Version	13.0
SpatiaLite-Version	5.0.1
QWT-Version	6.1.3
QScintilla2-Version	2.11.5
BS-Version	Windows 10 Version 2009
Aktive Python-Erweiterungen	active_layer_searchGeoCodingpluginbuilder3plugin_reloaderQNEAT3db_managerMetaSearchprocessing

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

version
PostgreSQL 11.12 (Debian 11.12-0+deb10u1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 8.3.0-6) 8.3.0, 64-bit
postgis_version 2.5 USE_GEOS=1 USE_PROJ=1 USE_STATS=1

[eurojam]

Helpful would be an expression type like "Fieldname" @> ARRAY['A', 'B'] which is possible in the filtering of layers with provider specific filter expressions

[troopa81]

@eurojam Could you tell me how you define and insert your array values ?

Even the label inside list are empty when I test with this data:

create table text_array ( id serial primary key, thetext character varying[] );
insert into text_array (thetext) values(array['C', 'D', 'E'])

[troopa81]

@eurojam Nevermind I suppose you have define the List widget type in the attribute forms properties

[eurojam]

No we didn't use the listwidget, we used a value relation widget with the multiple selection option:

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