PG NOTIFY not accessible

[gduls]

Describe the bug
Unable to access layer actions using pg_notify.
This may be an addendum to issue #25917

How to Reproduce

1. Create project with PostgreSQL/PostGIS connection.
2. Add a layer from said connection.
3. Attempt to either refresh said layer or perform a layer action using pg_notify.
4. Nothing happens.

QGIS and OS versions

QGIS version	3.14.16-Pi	QGIS code revision	a235a14
Compiled against Qt	5.12.8	Running against Qt	5.12.8
Compiled against GDAL/OGR	3.0.4	Running against GDAL/OGR	3.0.4
Compiled against GEOS	3.8.0-CAPI-1.13.1	Running against GEOS	3.8.0-CAPI-1.13.1
Compiled against SQLite	3.31.1	Running against SQLite	3.31.1
PostgreSQL Client Version	12.4 (Ubuntu 12.4-0ubuntu0.20.04.1)	SpatiaLite Version	4.3.0a
QWT Version	6.1.4	QScintilla2 Version	2.11.2
Compiled against PROJ	6.3.1	Running against PROJ	Rel. 6.3.1, February 10th, 2020
OS Version	Linux Mint 20
Active python plugins	DataUpdater; BRLSManager; PinSearch; addressfinder; latlontools; LayerUpdateManager; drafting_table; VicinityRestore; qgsAzimuth; nc_contour_download; processing; db_manager

Additional context
-This also occurs for a clean install on the same system.
-This also affects the most recent Windows version (as of this writing, 2020-09-23) with a clean install.
-It seems it could be a powerful feature, but it simply does not work.
-It may be confusing for new users to find tutorials on how to implement this feature, only to find it to be non-functional; despite the clearly displayed options to utilize it in both the layer rendering menu and the layer action menu.

[elpaso]

I've just tested both actions and generic notify on current master/linux with PG 10.14 with no issues.

[elpaso]

@gduls about the documentation issue, can you please file a separate ticket on https://github.com/qgis/QGIS-Documentation/ ?

[gioman]

I've just tested both actions and generic notify on current master/linux with PG 10.14 with no issues.

@elpaso so can we close this? Is this just a documentation issue?

[elpaso]

I have no idea: I cannot reproduce, the OP said that:

-It may be confusing for new users to find tutorials on how to implement this feature

so maybe we have a documentation issue.

[gduls]

@elpaso I can file a separate ticket for documentation, as this feature does not seem to be well documented (same with notify/refresh). Let me test this, once again, and be more explicit about what I am trying.

[gduls]

Additional Data to reproduce

1. Created new user profile and new project in EPSG:4326
2. Added connection to newly created postgis database named 'test2' and added data via
   SET standard_conforming_strings = OFF; DROP TABLE IF EXISTS "public"."test_point" CASCADE; DELETE FROM geometry_columns WHERE f_table_name = 'test_point' AND f_table_schema = 'public'; BEGIN; CREATE TABLE "public"."test_point" ( "ogc_fid" SERIAL, CONSTRAINT "test_point_pk" PRIMARY KEY ("ogc_fid") ); SELECT AddGeometryColumn('public','test_point','wkb_geometry',4326,'POINT',2); CREATE INDEX "test_point_wkb_geometry_geom_idx" ON "public"."test_point" USING GIST ("wkb_geometry"); ALTER TABLE "public"."test_point" ADD COLUMN "name" VARCHAR(10); INSERT INTO "public"."test_point" ("wkb_geometry" , "name") VALUES ('0101000020E6100000DEDDDDDDDDDDE3BF686666666666CE3F', 'test_point'); COMMIT;
3. Added an action (please see attached screenshot for details)
4. Tried to trigger action by the following methods:
   --psql shell
   test2=# notify qgis, 'hello';
   and
   test2=# BEGIN;
   test2=# NOTIFY qgis, 'hello;
   test2=# COMMIT;

Lastly, tried by using trigger defined as follows:
`BEGIN;
CREATE FUNCTION public.notify_qgis() RETURNS trigger
LANGUAGE plpgsql
AS $$
BEGIN NOTIFY qgis, 'hello';
RETURN NULL;
END;
$$;

CREATE TRIGGER notify_qgis_edit
AFTER INSERT OR UPDATE OR DELETE ON public.test_point
FOR EACH STATEMENT EXECUTE PROCEDURE public.notify_qgis();

COMMIT;`

Nothing works.

Is it possible this is a postgresql version issue? I was also unable to use pg_notify on a windows machine running postgresql version 12 64-bit, i think it was. And the version I am using for this case now is from a raspberry pi running the following:
PostgreSQL 11.7 (Raspbian 11.7-0+deb10u1) on arm-unknown-linux-gnueabihf, compiled by gcc (Raspbian 8.3.0-6+rpi1) 8.3.0, 32-bit

And POSTGIS version:
POSTGIS="2.5.1 r17027" [EXTENSION] PGSQL="110" GEOS="3.7.1-CAPI-1.11.1 27a5e771" PROJ="Rel. 5.2.0, September 15th, 2018" GDAL="GDAL 2.4.0, released 2018/12/14" LIBXML="2.9.4" LIBJSON="0.12.1" LIBPROTOBUF="1.3.1" RASTER

Am I missing some critical setting that needs to be enabled? Must the connection be SSL enabled? I am not sure what I am doing incorrectly here.
Below is a screenshot of the action created for the layer.

[gduls]

It seems the connection must be SSL enabled. I did not see this in the docs for pg_notify or qgis, but it makes sense, in retrospect. Thank you for your time! Closing.