Add follow button to patron profile pages

[pidgezero-one]

Closes #9358

Adds a follow button to a user's patron page.

Technical

• The button should only show if you are logged in, not looking at your own page, not already following the user, and the user's reading list is public.
• Moves the is_subscribed check business logic from MyBooksTemplate to the user level so that it can also be leveraged by the patron page. This seems like an appropriate place for it IMO as the user model also includes other object reference checks like is_usergroup_member.

Testing

I added a test patron via the provided instructions.
(The rest of my testing steps are outlined in the Screenshots section)

Screenshot

Viewing my own page: no follow button (public or private)

Viewing a public patron while logged in: follow button appears

Click the follow button: it becomes an unfollow button

Viewing a public patron logged out / incognito: follow button appears

Clicking the follow button while logged out prompts a login

After changing the test user's reading log to public, no button appears, logged in or logged out;

Stakeholders

@mekarpeles

Attribution Disclaimer: By proposing this pull request, I affirm to have made a best-effort and exercised my discretion to make sure relevant sections of this code which substantially leverage code suggestions, code generation, or code snippets from sources (e.g. Stack Overflow, GitHub) have been annotated with basic attribution so reviewers & contributors may have confidence and access to the correct context to evaluate and use this code.

[pidgezero-one]

Is there a safer way to get this, such as from get_users_settings? Or is this way of doing it considered pretty safe?

[mekarpeles]

I think this should be okay in this case.

[pidgezero-one]

Other than my open question in the files listing, I have two more:

• Is my placement of the follow button ideal (shown in the screenshots) or should I move it elsewhere?
• I think this might be an Infogami knowledge gap for me, but is there a macro of some sort to create new user accounts on a local dev environment? I'd like to verify that moving the business logic for is_subscribed to the user level doesn't break MyBooksTemplate, but http://localhost:8080/people/aaa/books is a broken link (both on this branch and on master) because (I assume) it's not a real user account due to the way I created it.

[mekarpeles]

Really nice work @pidgezero-one!

re: your questions above:

• placement of the button seems okay to me!
• re: creating new users on local env: https://github.com/internetarchive/openlibrary/wiki/Creating-and-Logging-in-as-a-new-user-on-your-local-client

A few edge cases for us to consider:

1. If the patron is logged out and the profile they're on is public, the patron should likely see a follow button
2. If the patron is already following the profile, they should see the unfollow button.

When I am logged in and go to https://testing.openlibrary.org/people/brewster, I see the correct thing:

When I am logged out, I don't:

Also, when I try to click Follow: https://testing.openlibrary.org/people/mekBot/follows.json?debug=true I get

<class 'AttributeError'> at /people/mekBot/follows.json
type object 'PubSub' has no attribute 'get_subscriptions'

On /people/brewster/books it works correctly where, once I follow, I see unfollow btn

Test Checklist

• If I'm logged in already following public profile X, I should see Unfollow btn
• If I am logged out and profile X is public, I should see Follow btn
• If click Follow, the flow should succeed :)

[pidgezero-one]

@mekarpeles Thank you! :) I've pushed another commit that addresses these issues, and have updated my screenshots in the PR description according to the checklist provided.