Make PostgresUserPasswordProfileMapping schema profile argument optional

[tatiana]

Context

As of Cosmos 1.2.3, when users instantiate a ProfileMapping using PostgresUserPasswordProfileMapping, Cosmos expects users to define a schema:

astronomer-cosmos/cosmos/profiles/postgres/user_pass.py

Line 24 in 773fa27

"schema",

As illustrated below:

from cosmos.profiles import PostgresUserPasswordProfileMapping
profile_config = ProfileConfig(
   profile_name="my_profile_name",
   target_name="my_target_name",
   profile_mapping=PostgresUserPasswordProfileMapping(
       conn_id="my_postgres_conn_id",
       profile_args={
           "database": "my_postgres_database",
           "schema": "stage",
       },
   ),
)

However, dbt-postgres does not have this property as a mandatory field. This is usually not an issue unless users want to define schemas specific to models. When this happens, dbt considers the schema set at the profile level as the target_schema for applying a custom_schema (macro generate_schema_name): https://docs.getdbt.com/docs/build/custom-schemas.

The consequence is that model-specific schemas are resolved incorrectly if the profile schema="", by having an underscore pre-pre-appended.

This issue was originally raised by tariq.f in the Airflow #ariflow-dbt slack channel:
https://apache-airflow.slack.com/archives/C059CC42E9W/p1700049843620749

Acceptance criteria

• Make PostgresUserPasswordProfileMapping schema profile argument optional

[dosubot]

🤖

Hello again @tatiana! It's great to see you're still actively contributing to the Cosmos project!

It seems like you've got this under control, if you want help or have specific questions, let me know what I can do for you!