Getting active PostgreSQL connection username when stored through authentication configuration in QGIS 3.16

Question

How do I get the username on the current layer PostGIS in QGIS 3.16.2-Hannover? We tried examples: Getting active PostgreSQL connection username when stored through authentication configuration in QGIS 3, but they don't work.

When running this script, variable username is empty:

layer = iface.activeLayer()
provider = layer.dataProvider()
username = QgsDataSourceUri(provider.dataSourceUri()).username()
print (username)

This is result of provider.dataSourceUri()):

<QgsDataSourceUri: dbname='postgres' host= localhost port=5432 sslmode=disable key='id' srid=4326 type=Point checkPrimaryKeyUnicity='1' table="locations"."airlines" (geom)>

The value of the username is missing, the question is how to get the username for the current layer?

• Ian Turton: What does "they don't work" mean?
• Nil: I have tried it as well. I got also username is empty but the reason (in my case) I am connected with local credentials so there is no user and psw. Can you check if you see the 'user' when you print out provider.dataSourceUri()?
• dd_a: I don't understand: you are referring to a question that gives you the solution, doesn't it ?
• Andrey Sirbu: the solution to the question I am referring to does not answer my question. Function - QgsDataSourceUri(provider.dataSourceUri()).username() return empty string
• Nil: @AndreySirbu what does it return if you call only provider.dataSourceUri()??

Answer 1

You can select your PostgreSQL user using the 'PostgreSQL Execute SQL' command in the Processing toolbox.

Query:

SELECT user;

enter image description here

• Andrey Sirbu: how to get user name from script?
• Andrey Sirbu: How to use python function?