[FIX] mail: get members on channel_info

Before this commit, when accessing a channel after a page reload,
the list of members in a channel was not known until the composer
on this channel has the focus, either in the Discuss app or in a
chat window.

This was a good-enough condition when information about members
was limited to mention suggestions, which requires having the
focus on the composer. However, with the 'is typing' features
on channels, it requires being aware of the members of the channel
at the moment of the rendering in discuss or in a chat window.

This commit fixes the issue by providing the list of channel
members when retrieving information about the channel.

Without this fix, the 'is typing' notifications could sometimes
not determine the name(s) and email(s) of user(s) typing something.

2 files changed, 31 insertions, 13 deletions

diff --git a/addons/mail/models/mail_channel.py b/addons/mail/models/mail_channel.py
index 2b060cf1276..778ee09d4c4 100644
--- a/addons/mail/models/mail_channel.py
+++ b/addons/mail/models/mail_channel.py
@@ -537,10 +537,13 @@ class Channel(models.Model):
             :rtype : list(dict)
         """
         channel_infos = []
-        partner_channels = self.env['mail.channel.partner']
-        # find the channel partner state, if logged user
-        if self.env.user and self.env.user.partner_id:
-            partner_channels = self.env['mail.channel.partner'].search([('partner_id', '=', self.env.user.partner_id.id), ('channel_id', 'in', self.ids)])
+
+        # all relations partner_channel on those channels
+        all_partner_channel = self.env['mail.channel.partner'].search([('channel_id', 'in', self.ids)])
+
+        # all partner infos on those channels
+        partner_infos = all_partner_channel.mapped('partner_id').read(['id', 'name', 'email'])
+
         # for each channel, build the information header and include the logged partner information
         for channel in self:
             info = {
@@ -573,17 +576,28 @@ class Channel(models.Model):
                 if last_message:
                     info['last_message'] = last_message[0].get('last_message')
 
-            # add user session state, if available and if user is logged
-            if partner_channels.ids:
-                partner_channel = partner_channels.filtered(lambda c: channel.id == c.channel_id.id)
-                if len(partner_channel) >= 1:
-                    partner_channel = partner_channel[0]
-                    info['state'] = partner_channel.fold_state or 'open'
-                    info['is_minimized'] = partner_channel.is_minimized
-                    info['seen_message_id'] = partner_channel.seen_message_id.id
+            # listeners of the channel
+            channel_partners = all_partner_channel.filtered(lambda pc: channel.id == pc.channel_id.id)
+
+            # find the channel partner state, if logged user
+            partner_channel = self.env['mail.channel.partner']
+            if self.env.user and self.env.user.partner_id:
+                partner_channel = channel_partners.filtered(lambda pc: pc.partner_id.id == self.env.user.partner_id.id)
                 # add needaction and unread counter, since the user is logged
                 info['message_needaction_counter'] = channel.message_needaction_counter
                 info['message_unread_counter'] = channel.message_unread_counter
+
+            # add user session state, if available and if user is logged
+            if len(partner_channel.ids):
+                partner_channel = partner_channel[0]
+                info['state'] = partner_channel.fold_state or 'open'
+                info['is_minimized'] = partner_channel.is_minimized
+                info['seen_message_id'] = partner_channel.seen_message_id.id
+
+            # add members infos
+            partner_ids = channel_partners.mapped('partner_id').ids
+            info['members'] = [partner_info for partner_info in partner_infos if partner_info['id'] in partner_ids]
+
             channel_infos.append(info)
         return channel_infos
 
diff --git a/addons/mail/static/src/js/models/threads/channel.js b/addons/mail/static/src/js/models/threads/channel.js
index ff90ca8edfb..f6839873ef7 100644
--- a/addons/mail/static/src/js/models/threads/channel.js
+++ b/addons/mail/static/src/js/models/threads/channel.js
@@ -29,6 +29,10 @@ var Channel = SearchableThread.extend(ThreadTypingMixin, {
      * @param  {boolean} params.data.is_moderator whether the current user is
      *   moderator of this channel.
      * @param {string} [params.data.last_message_date] date in server-format
+     * @param {Object[]} [params.data.members=[]]
+     * @param {integer} [params.data.members[i].id]
+     * @param {string} [params.data.members[i].name]
+     * @param {string} [params.data.members[i].email]
      * @param {integer} [params.data.message_unread_counter]
      * @param {boolean} [params.data.moderation=false] whether the channel is
      *   moderated or not
@@ -61,7 +65,7 @@ var Channel = SearchableThread.extend(ThreadTypingMixin, {
         this._isModerated = data.moderation;
         this._isMyselfModerator = data.is_moderator;
         this._lastMessageDate = undefined;
-        this._members = [];
+        this._members = data.members || [];
         // Deferred that is resolved on fetched members of this channel.
         this._membersDef = undefined;
         // number of messages that are 'needaction', which is equivalent to the