Truncate Channel

Truncating a channel removes all messages but preserves the channel data and members. To delete both the channel and its messages, use Delete Channel instead.

Truncation can be performed client-side or server-side. Client-side truncation requires the TruncateChannel permission.

On server-side calls, use the user_id field to identify who performed the truncation.

By default, truncation hides messages. To permanently delete messages, set hard_delete to true. Truncation applies to every member by default. Set member_ids to scope it to specific members instead.

Truncate a Channel

Channel->Truncate();

// Or with parameters:
Channel->Truncate(
  true,  // bHardDelete
  {},   // TruncatedAt
  FMessage{TEXT("Dear Everyone. The channel has been truncated.")},
  false,  // bSkipPush
  []
  {
    // Channel is truncated
  });

Truncate for Specific Members

Set member_ids to hide the message history for specific members only. Every other member keeps their full view, and no messages are deleted. They stay in the channel and remain visible to everyone not listed.

Messages created before truncated_at are hidden from the listed members. When truncated_at is omitted it defaults to the time of the request, hiding the history to date.

This sets the same per-member history cutoff as Hide Channel with clear_history, but it does not hide the channel. The channel stays in the listed members' channel lists, and every member receives channel.truncated instead of the hiding user alone receiving channel.hidden.

// Hide the history for two members; everyone else keeps their full view
await channel.truncate({
  member_ids: ["jane", "john"],
});

// Hide only the messages created before a given time
await channel.truncate({
  member_ids: ["jane"],
  truncated_at: new Date("2026-01-01T00:00:00Z"),
});

Constraints

• Every ID in member_ids must belong to a current member of the channel. The request fails with not all users are active channel members otherwise.
• member_ids accepts at most 100 IDs.
• hard_delete cannot be combined with member_ids. Member-scoped truncation only hides messages, it never deletes them.
• truncated_at replaces each listed member's existing cutoff rather than keeping the later of the two. A second call with an earlier truncated_at makes the messages between the two times visible to those members again.
• truncated_at must be later than the channel's last whole-channel truncation and not in the future. Otherwise the request fails with "truncated_at" field must be more recent than previous one or "truncated_at" field must not be more recent than current time. A fixed past date, like the 2026-01-01 example above, fails on any channel truncated after it.
• The channel.truncated event is delivered to every member of the channel, not only the members listed in member_ids. Client SDKs that clear their cached messages on this event do so for all members; the messages are unaffected on the server and reappear on the next fetch.

Truncate Options