[Reader] Subscribed Sites list is incomplete

[RenanLukas]

This issue and it's cause were discovered by @daniloercoli.

When the user has many blogs (probably > 100, see below) some of them won't be shown in the Subscriptions feed or Manage Tags & Blogs screen. This happens because paging is not handled (like it is on web client) in our implementation of the read/following/mine endpoint.

We have to implement paging in this endpoint, which includes adding number and page query parameters (see p1708454312137679/1708440747.970699-slack-C01CW1VMLAF).

This issue seems to be reproducible for users with > 100 subscribed blogs because 100 is probably the default value for number.

Warning

It's worth saying that besides the endpoint paging not being implemented we also limit the number of displayed posts in the client (see ReaderPostAdapter).

Expected behavior

All subscribed blogs are shown.

Actual behavior

Not all subscribed blogs are shown.

Steps to reproduce the behavior

1 - Subscribe to > 100 blogs;
2 - Open Reader;
3 - Select Subscriptions feed;
4 - Verify the subscribed blogs chip: the number is wrong (compare it with web);
5 - Open "Manage Tags & Blogs" screen: some blogs that the user is subscribed to are missing.

[dangermattic]

Thanks for reporting! 👍

[daniloercoli]

I suggest, as an initial implementation, to adopt the same approach as the Web Reader. They fetch all pages in the background until there are no more results. You can see it in action here https://wordpress.com/read/subscriptions and filter for following/mine in the nwetwork tab. (Ref: https://public-api.wordpress.com/rest/v1.2/read/following/mine?number=100&page=1).

[daniloercoli]

Noticed that we already have another issue tracking the same problem: #13989

[daniloercoli]

Fixed in #20430