Hide inactive users from the blog post author dropdown

[VirginiaDooley]

Closes #535

With this work, blog posts can only be assigned to active authors.

[codecov]

Codecov Report

Merging #546 (24d6fc9) into master (303a31b) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #546   +/-   ##
=======================================
  Coverage   70.01%   70.01%           
=======================================
  Files          41       41           
  Lines         637      637           
=======================================
  Hits          446      446           
  Misses        191      191           

Impacted Files	Coverage Δ
democracy_club/apps/hermes/models.py	94.21% <ø> (ø)

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[VirginiaDooley]

Restore old blog authors

[symroe]

TIL limit_choices_to! Nice!

Can you check one thing though: If we edit an old blog post with an inactive user, what happens?

So the steps would be:

1. Create a user, publish a blog post by them
2. Mark that user as inactive
3. As a different user, edit the post and save
4. Does the initial user get saved, or removed from the post?

[VirginiaDooley]

TIL limit_choices_to! Nice!

Can you check one thing though: If we edit an old blog post with an inactive user, what happens?

So the steps would be:

1. Create a user, publish a blog post by them
2. Mark that user as inactive
3. As a different user, edit the post and save

Since the original author has been marked inactive, I am prompted to choose an active author from the list to save the edited post.

4. Does the initial user get saved, or removed from the post?

Yes, removed.

[symroe]

Hmm, in that case, I think we might need another approach here, as we want to keep old authors if we edit their posts (for whatever reason).

Can you take a look at the ModelAdmin form in admin.py and see if we can only limit the options for new posts rather than existing ones? That was the approach I was thinking of before I knew about limit_choices_to