The OR conditions in the WHERE clause prevented the query from
effectively filtering the messages related to the user quickly, this
change helps gets around this by allowing the database to limit
the rows in the messages table it needs to scan significantly.
When the messagingallusers setting is disabled only contacts that are
on the same course as the user should be returned as results.
We can reduce the number of candidate users significantly by
pre-filtering them by being enrolled on the same courses as the user
performing the search.
Since we must also return the user themselves sometimes, even when they
are not enrolled on a course I used a UNION as the most efficient way of
retriving them, this meant that the order by had to reference returned
columns by number to be sufficiently cross-database compatiable.
This class would belong more appropriately within the 'user' API
(core_user) instead of within the 'core' API, since it is
directly related to user data.
Since the class has only just been added to Moodle, now is a good
time to move it.
In all cases changes have been kept to a minimum while not making
the code completely horrible. For example, there are many instances
where it would probably be better to rewrite a query entirely, but
I have not done that (in order to reduce the risk of changes).
If blocking will have no effect (ie. you are attempting to block
the admin) the 'Block' button will not be shown and instead a
message will be shown explaining why you can not block the user.
Instead of creating all the self-conversations during the upgrading,
some code has been added to the get_conversations and to the
get_conversation_counts to create it whe it doesn't exist.
Two modes of visibility checking are supported, depending on the value
of the 'messagingallusers' site setting (site-wide messaging):
- If site-wide messaging is enabled, a user may only be returned in
search results if the searching user can view their profile somewhere
(either the site profile or any course profile).
- If site-wide messaging is disabled, a user may only be returned in
search results if the searching user shares a course with them and can
view their course profile in the shared course.
Added new MESSAGE_CONVERSATION_TYPE_SELF type for self-conversations
and upgraded legacy self-conversations to the new type, removing
repeated members in the message_conversation_members table.
Besides, from now, a self-conversation will be created by default for
all the existing users.
All the self-conversations have been also starred and a default message
will be displayed always to explain how to use them.
Conversation name and subname should support filters, so the data should
be passed through format_string, and advertised in the external params
as PARAM_TEXT.
