[GitHub] [airflow] RikHeijdens commented on a change in pull request #14452: Gracefully handle missing start_date and end_date for DagRun

[GitBox <gi...@apache.org>]

RikHeijdens commented on a change in pull request #14452:
URL: https://github.com/apache/airflow/pull/14452#discussion_r582829692



##########
File path: airflow/www/views.py
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@@ -3302,7 +3302,7 @@ class DagRunModelView(AirflowModelView):
         'external_trigger',
         'conf',
     ]
-    edit_columns = ['state', 'dag_id', 'execution_date', 'run_id', 'conf']
+    edit_columns = ['state', 'dag_id', 'execution_date', 'start_date', 'end_date', 'run_id', 'conf']

Review comment:
       Sure! Happy to clarify why I choose to venture down this route.
   
   The [`DagRunEditForm`](https://github.com/apache/airflow/blob/master/airflow/www/forms.py#L172-L173) contains the `start_date` and `end_date` fields, and these are supposed to be "read-only" as they use [`AirflowDateTimePickerROWidget`](https://github.com/apache/airflow/blob/45e72ca83049a7db526b1f0fbd94c75f5f92cc75/airflow/www/widgets.py#L51).
   
   However, what would happen when I would use the `DagRunEditForm` through the Web UI is that the `start_date` and `end_date` would be set to `NULL` when submitting the form (even if they were set previously). This happened because `start_date` and `end_date` are not contained in the `edit_columns` list, and thus the form would not contain any data for them and overwrite old values.
   
   By adding `start_date` and `end_date` as entries to `edit_columns` columns, the widget displays them as "read-only" in the form, and no longer nulls them out when the form is submitted.
   
   Note that any DagRun that is in the `running` state, but does not have a `start_date` set may cause a scheduler crash. This crash is avoided by https://github.com/apache/airflow/pull/14452/commits/a780e8a029c3801cd60da784fcf0b7af2c58bf13.




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