keep track of channel followers

[pdpinch]

In discussing #1249 we learned that reddit does not have an API for getting a list of subreddit subscribers ("channel followers" in discussions). In order to be able to count and list followers, we will need to store this relationship in django.

acceptance criteria

• [x] model for storing user/channel subscription status
• [x] update the subscribe API in discussions to store the subscription state of the user
• [x] whenever the subscription state is updated, update the ES profile index
• [x] update the backpopulate_default_channel management command to also store subscriptions
• [x] api for getting a list of followers of a channel

related issues

• button and api for following/unfollowing channels

[mbertrand]

@pdpinch does it make sense to add 'Update the Elasticsearch profile doc (author_channel_membership) when channel subscription status changes' to this issue, or create a new issue for it?

[pdpinch]

@mbertrand I added it to the checklist for this issue, since we're going to be updating the APIs anyway

[mbertrand]

@pdpinch is it correct that a channel follower is not necessarily a moderator or contributor? I don't see any option in the UI to follow a channel (just posts), but the Channel object returned by the API includes the following attributes:

 user_is_contributor
 user_is_moderator
 user_is_subscriber

I'm assuming that a user is a follower if user_is_subscriber is true? And we should store all the above in Django: a channel's moderators, contributors, and subscribers?

[Ferdi]

is it correct that a channel follower is not necessarily a moderator or contributor? Yes. Private channels have: contributors, moderators, and subscribers Public channels have : Moderators and subscribers

"Subscribe" just affects your front page feed . So for example, you can be a member of a private channel but you unsubscribe because the channel is noisy and you dont want that channel to dominate your feed. But you are still a member and can access the channel if you wanted.

[pdpinch]

Just to be as clear as possible:

is it correct that a channel follower is not necessarily a moderator or contributor?

Yes.

I don't see any option in the UI to follow a channel

We haven't implemented it yet, but there is a design: https://zpl.io/VQEJqKk

So clicking the red "follow" button would add the user as subscriber.

I'm assuming that a user is a follower if user_is_subscriber is true?

We're working on a mapping of roles in code to roles in the UI. This is preliminary:

user_is_contributor => member user_is_moderator => moderator user_is_subscriber => follower

As Ferdi said, each of those are independent, and not all of them are available in all channels.

we should store all the above in Django: a channel's moderators, contributors, and subscribers?

yep

[mbertrand]

@pdpinch I checked the last checkbox, ok to close?