Discussion groups

Groups can be associated to a channel as a discussion group, to allow users to discuss about posts.

Channel comments

boolFalse#bc799737 = Bool;
boolTrue#997275b5 = Bool;

channelFull#f2bcb6f flags:# can_view_participants:flags.3?true can_set_username:flags.6?true can_set_stickers:flags.7?true hidden_prehistory:flags.10?true can_set_location:flags.16?true has_scheduled:flags.19?true can_view_stats:flags.20?true blocked:flags.22?true flags2:# can_delete_channel:flags2.0?true antispam:flags2.1?true participants_hidden:flags2.2?true translations_disabled:flags2.3?true stories_pinned_available:flags2.5?true view_forum_as_messages:flags2.6?true id:long about:string participants_count:flags.0?int admins_count:flags.1?int kicked_count:flags.2?int banned_count:flags.2?int online_count:flags.13?int read_inbox_max_id:int read_outbox_max_id:int unread_count:int chat_photo:Photo notify_settings:PeerNotifySettings exported_invite:flags.23?ExportedChatInvite bot_info:Vector<BotInfo> migrated_from_chat_id:flags.4?long migrated_from_max_id:flags.4?int pinned_msg_id:flags.5?int stickerset:flags.8?StickerSet available_min_id:flags.9?int folder_id:flags.11?int linked_chat_id:flags.14?long location:flags.15?ChannelLocation slowmode_seconds:flags.17?int slowmode_next_send_date:flags.18?int stats_dc:flags.12?int pts:int call:flags.21?InputGroupCall ttl_period:flags.24?int pending_suggestions:flags.25?Vector<string> groupcall_default_join_as:flags.26?Peer theme_emoticon:flags.27?string requests_pending:flags.28?int recent_requesters:flags.28?Vector<long> default_send_as:flags.29?Peer available_reactions:flags.30?ChatReactions stories:flags2.4?PeerStories wallpaper:flags2.7?WallPaper = ChatFull;

messages.chats#64ff9fd5 chats:Vector<Chat> = messages.Chats;

messageReplies#83d60fc2 flags:# comments:flags.0?true replies:int replies_pts:int recent_repliers:flags.1?Vector<Peer> channel_id:flags.0?long max_id:flags.2?int read_max_id:flags.3?int = MessageReplies;

messages.discussionMessage#a6341782 flags:# messages:Vector<Message> max_id:flags.0?int read_inbox_max_id:flags.1?int read_outbox_max_id:flags.2?int unread_count:int chats:Vector<Chat> users:Vector<User> = messages.DiscussionMessage;


channels.setDiscussionGroup#40582bb2 broadcast:InputChannel group:InputChannel = Bool;
channels.getGroupsForDiscussion#f5dad378 = messages.Chats;

messages.getDiscussionMessage#446972fd peer:InputPeer msg_id:int = messages.DiscussionMessage;

A discussion group can be associated to a channel using channels.setDiscussionGroup.
The discussion group can be accessed in the client by clicking on the discuss button of the channel, or by accessing the comment section of a specific post; the discussion group ID is also present in the linked_chat_id field of the channelFull constructor.

All messages sent to the channel will also be forwarded to the linked group (with sender peer from_id equal to the peer of the linked channel); those messages will also be automatically pinned in the group.

The comment section of a channel post is simply the message thread of the automatically forwarded channel message in the linked discussion supergroup.
Thus, the comment section of a particular post can be disabled by removing the autoforwarded channel post message from the discussion group.

A messageReplies constructor will be attached the channel post in the original channel, containing information about the comment section, specifically:

  • replies.channel_id will contain the ID of the linked discussion supergroup
  • replies.recent_repliers will contain information about the last few comment posters for a specific thread, to show a small list of commenter profile pictures in client previews.
  • replies.replies will contains the total number of replies in the comment section.
  • replies.max_id may contain the ID of the latest message in the comment section, if any.
  • replies.replies_pts may contain the PTS of the autoforwarded channel message that started the comment section.

The same messageReplies constructor with the usual flags for a thread (i.e. without channel_id, recent_replies) will also be present in the message automatically forwarded to the discussion group, as for all group messages that start a thread.

Use messages.getDiscussionMessage to obtain the initial messages of the message thread of the autoforwaded channel message in the linked discussion supergroup.

The messages are returned in a reverse chronological order (i.e., in order of decreasing message ID); thus the last message returned by the method will be the autoforwarded channel message that started the comment section.


messageFwdHeader#4e4df4bb flags:# imported:flags.7?true saved_out:flags.11?true from_id:flags.0?Peer from_name:flags.5?string date:int channel_post:flags.2?int post_author:flags.3?string saved_from_peer:flags.4?Peer saved_from_msg_id:flags.4?int saved_from_id:flags.8?Peer saved_from_name:flags.9?string saved_date:flags.10?int psa_type:flags.6?string = MessageFwdHeader;

messageReplyHeader#afbc09db flags:# reply_to_scheduled:flags.2?true forum_topic:flags.3?true quote:flags.9?true reply_to_msg_id:flags.4?int reply_to_peer_id:flags.0?Peer reply_from:flags.5?MessageFwdHeader reply_media:flags.8?MessageMedia reply_to_top_id:flags.1?int quote_text:flags.6?string quote_entities:flags.7?Vector<MessageEntity> quote_offset:flags.10?int = MessageReplyHeader;

message#76bec211 flags:# out:flags.1?true mentioned:flags.4?true media_unread:flags.5?true silent:flags.13?true post:flags.14?true from_scheduled:flags.18?true legacy:flags.19?true edit_hide:flags.21?true pinned:flags.24?true noforwards:flags.26?true invert_media:flags.27?true id:int from_id:flags.8?Peer peer_id:Peer saved_peer_id:flags.28?Peer fwd_from:flags.2?MessageFwdHeader via_bot_id:flags.11?long reply_to:flags.3?MessageReplyHeader date:int message:string media:flags.9?MessageMedia reply_markup:flags.6?ReplyMarkup entities:flags.7?Vector<MessageEntity> views:flags.10?int forwards:flags.10?int replies:flags.23?MessageReplies edit_date:flags.15?int post_author:flags.16?string grouped_id:flags.17?long reactions:flags.20?MessageReactions restriction_reason:flags.22?Vector<RestrictionReason> ttl_period:flags.25?int = Message;

updateNewMessage#1f2b0afd message:Message pts:int pts_count:int = Update;
updateNewChannelMessage#62ba04d9 message:Message pts:int pts_count:int = Update;


contacts.blockFromReplies#29a8962c flags:# delete_message:flags.0?true delete_history:flags.1?true report_spam:flags.2?true msg_id:int = Updates;

contacts.resolveUsername#f93ccba3 username:string = contacts.ResolvedPeer;

Since a user can comment in channel posts without joining the actual discussion supergroup, there must be a way for them to receive notifications about replies in comment sections.
For this reason, a special @replies username is provided. Its ID for main and testing endpoints can be seen in the tdlib sources.

When someone replies to one of our messages in the comment section of a channel post, and the user is not subscribed to the discussion group, the client will receive two updates:

  • An updateNewChannelMessage from the discussion group itself, structured just like any other update coming from a subscribed group, with:
    • id set to the ID of the reply
    • from_id set to the peer that replied to us
    • peer_id set to the peer of the discussion group
    • reply_to.reply_to_msg_id set to the ID of our message
    • reply_to.reply_to_top_id set to the thread ID.
  • An updateNewMessage
    • id set to the common ID sequence for users
    • from_id set to the peer of @replies
    • peer_id set to our own peer
    • fwd_from.saved_from_msg_id set to the ID of the reply
    • fwd_from.from_id set to the peer that replied to us
    • reply_to.reply_to_peer_id set to the peer of the discussion group
    • reply_to.reply_to_msg_id set to the ID of our message
    • reply_to.reply_to_top_id set to the thread ID

Clients should display messages coming from @replies as a read-only supergroup, with each reply displayed as a separate message from the author of the reply, with a "View in chat" button like for channel comments.

contacts.blockFromReplies may be used to stop getting notifications about thread replies from a certain user in @replies.

Linking a discussion group

To obtain a list of admined supergroups that a channel admin can possibly associate to a channel, use channels.getGroupsForDiscussion.
Returned basic group chats must be first upgraded to supergroups before they can be set as a discussion group.
Before linking a supergroup to a channel, access to the supergroup's old messages must also be enabled using channels.togglePreHistoryHidden.

To set a returned supergroup as a discussion group use channels.setDiscussionGroup.


boolFalse#bc799737 = Bool;
boolTrue#997275b5 = Bool;

messages.chats#64ff9fd5 chats:Vector<Chat> = messages.Chats;


channels.setDiscussionGroup#40582bb2 broadcast:InputChannel group:InputChannel = Bool;
channels.getGroupsForDiscussion#f5dad378 = messages.Chats;

channels.togglePreHistoryHidden#eabbb94c channel:InputChannel enabled:Bool = Updates;

Requiring users to join the group

channel#aadfc8f flags:# creator:flags.0?true left:flags.2?true broadcast:flags.5?true verified:flags.7?true megagroup:flags.8?true restricted:flags.9?true signatures:flags.11?true min:flags.12?true scam:flags.19?true has_link:flags.20?true has_geo:flags.21?true slowmode_enabled:flags.22?true call_active:flags.23?true call_not_empty:flags.24?true fake:flags.25?true gigagroup:flags.26?true noforwards:flags.27?true join_to_send:flags.28?true join_request:flags.29?true forum:flags.30?true flags2:# stories_hidden:flags2.1?true stories_hidden_min:flags2.2?true stories_unavailable:flags2.3?true id:long access_hash:flags.13?long title:string username:flags.6?string photo:ChatPhoto date:int restriction_reason:flags.9?Vector<RestrictionReason> admin_rights:flags.14?ChatAdminRights banned_rights:flags.15?ChatBannedRights default_banned_rights:flags.18?ChatBannedRights participants_count:flags.17?int usernames:flags2.0?Vector<Username> stories_max_id:flags2.4?int color:flags2.7?PeerColor profile_color:flags2.8?PeerColor emoji_status:flags2.9?EmojiStatus level:flags2.10?int = Chat;


channels.toggleJoinToSend#e4cb9580 channel:InputChannel enabled:Bool = Updates;

Admins may use channels.toggleJoinToSend to force users to join a discussion group before commenting.
The channel.join_to_send flag will be set accordingly, and all attempts by non-members to send a message to the group will return a CHAT_GUEST_SEND_FORBIDDEN RPC error.