galak75 commented on issue #4743: [AIRFLOW-3871] render Operators template fields recursively URL: https://github.com/apache/airflow/pull/4743#issuecomment-472148500 @bjoernpollex-sc : thanks a lot for your feedback I actually didn't see your comment on Jira. I do not understand why it did not pop up. I have some questions about it: > There might be fields I don't want rendered (maybe I use Jinja templating internally) This is a good point. In such a case, shouldn't Airflow templating process be preferred? ---- > Due to the dynamic nature of Python, I might want to render fields that can't be found via introspection I'm pretty new with python, how this could happen? Isn't introspection meant to provide all existing attributes, methods, and so on, on an object? Do you have any example or reading about it? ---- > I think a viable alternative would be to use the same approach as for operators - declare which fields need templating using a template_fields class variable. It is a good alternative to avoid the first point: just choose the fields we want to be templated. But then, we need to manipulate a class (add a class attribute) to make sure its fields will be rendered. One thing I really appreciate with approach # 3 is that is works without any change on classes. just setting a templated value on any attribute from any class (in an operator template_field), and this value will be rendered during DAG execution. If we have to customize a class so that its inner fields are templated, would you rather add a `template_field` class attribute, or define a `render_template` custom method (approach # 2) I hope I'm clear enough... Thank you in advance for your answer.
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