[jira] [Commented] (AIRFLOW-3705) PostgresHook's get_conn method calls incorrect attribute by default

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/AIRFLOW-3705?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16909367#comment-16909367 ] 

ASF GitHub Bot commented on AIRFLOW-3705:
-----------------------------------------

coopergillan commented on pull request #5841: [AIRFLOW-3705] Fix PostgresHook get_conn to use conn_name_attr
URL: https://github.com/apache/airflow/pull/5841
 
 
   Make sure you have checked _all_ steps below.
   
   ### Jira
   
   - [x] My PR addresses the following [Airflow Jira](https://issues.apache.org/jira/browse/AIRFLOW-3705) issue and references it in the PR title.
     - https://issues.apache.org/jira/browse/AIRFLOW-3705
   
   ### Description
   
   - [x] Here are some details about my PR, including screenshots of any UI changes:
   
   Update the `get_conn` method of `PostgresHook` to ensure that the `conn_name_attr` specified is used to establish the connection via `psycopg2`.
   
   This is an issue when subclassing `PostgresHook`. The `postgres_conn_id` attribute must be overridden since it is explicitly used in establishing the connection. Now any given `conn_name_attr` set when subclassing will be used when connecting.
   
   ### Tests
   
   - [s] My PR adds the following unit tests __OR__ does not need testing for this extremely good reason:
     - Adds a small subclass of `PostgresHook` with a new `conn_name_attr` which is used in `TestPostgresHookConn`. This illustrates the problem with the default behavior for `get_conn` with three test failures that say:
   
   ```bash
   AttributeError: 'UnitTestPostgresHook' object has no attribute 'postgres_conn_id'
   ```
   
   ### Commits
   
   - [x] My commits all reference Jira issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "[How to write a good git commit message](http://chris.beams.io/posts/git-commit/)":
     1. Subject is separated from body by a blank line
     1. Subject is limited to 50 characters (not including Jira issue reference)
     1. Subject does not end with a period
     1. Subject uses the imperative mood ("add", not "adding")
     1. Body wraps at 72 characters
     1. Body explains "what" and "why", not "how"
   
   ### Code Quality
   
   - [ ] Passes `flake8`
   
 
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> PostgresHook's get_conn method calls incorrect attribute by default 
> --------------------------------------------------------------------
>
>                 Key: AIRFLOW-3705
>                 URL: https://issues.apache.org/jira/browse/AIRFLOW-3705
>             Project: Apache Airflow
>          Issue Type: Bug
>          Components: database
>    Affects Versions: 1.10.2
>            Reporter: Cooper Gillan
>            Assignee: Cooper Gillan
>            Priority: Minor
>
> Sub-classing {{PostgresHook}} to specify separate connections is currently not possible due to [{{get_conn}} calling {{self.postgres_conn_id}} directly|https://github.com/apache/airflow/blob/c030729dcbe35a2a4869e46b57a761c8376ede8d/airflow/hooks/postgres_hook.py#L46]. It should be possible to set different values for [{{self.conn_name_attr}}|https://github.com/apache/airflow/blob/c030729dcbe35a2a4869e46b57a761c8376ede8d/airflow/hooks/postgres_hook.py#L37], in sub-classes of the hook.
> For example, if sub-classing {{PostgresHook}} to set up separate named connections to multiple Postgres instances, the {{postgres_conn_id}} of the sub-class must be set specifically. This is true despite the fact that {{conn_name_attr}} is set up in a way that should allow any connection to be specified.



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