This simplifies things for all codepaths not involving this feature.
Using this feature becomes slightly easier when you're already
defining a subclass, but now requires you to define a subclass.
Currently we use it just once out of >100 uses of JsonableError, and
that use already has a subclass, so this seems like a win.
With #5598 there will soon be an application-level error code
optionally associated with a `JsonableError`, so rename this
field to make clear that it specifically refers to an
HTTP status code.
Also take this opportunity to eliminate most of the places
that refer to it, which only do so to repeat the default value.
The whole thing is an error, so "message" is a more apt word for the
error message specifically. We abbreviate that as `msg` in the actual
HTTP responses and in the signatures of `json_error` and friends, so
do the same here.
In most cases, we do have the data for which other user was
responsible for subscribing the target user to new streams.
The main case where we don't is when the user is created and gets the
default streams.
When we create a stream, we usually send a welcome message on the
stream itself as well as an announcement on the announcement stream,
but we no longer PM the individual users. Hopefully this will be
more pleasant for users (less spammy), and it also will make creating a
stream a lot faster.
We still send notifications when we add subscribers to an existing
stream.
This is one of the last major endpoints that were still done in the
pre-REST style.
While we're at it, we change the endpoint to expect a stream ID, not a
stream name.
The new function takes a full UserProfile object for the sender,
which allows us to avoid O(N) calls when creating the stream to
find the user profile of the notification bot. (The calls were
already cached, so this won't necessarily be a huge performance
win.)
We also don't have to worry about sending a blank subject any more.
The new, more direct interface for prepping internal stream
messages circumvents the bug-prone extract_recipients() method,
which has the pitfall that it will try to parse a stream name
as JSON. It also takes a UserProfile object for the sender, so
it's a bit more type-safe.
A bug in Zulip's implementation of the "stream exists" endpoint meant
that any user of a Zulip server could subscribe to an invite-only
stream without needing to be invited by using the "autosubscribe"
argument.
Thanks to Rafid Aslam for discovering this issue.
In order to correctly handle messages sent by cross-realm bots, we
need to specify the realm that the messages are being sent into in the
send message code path. The commit and its successors convert that
code path to include the realm the message is being sent to explicitly.
