SignalR - Leave All Groups

问题:

Using a SignalR hub clients can be added or removed from a group. A client can belong to multiple groups. Is it possible to remove a client from every group it currently belongs to? I guess what I'm looking for is something like Clients[*allgroups*].leave(Context.ConnectionId)

回答1:

Looks like they have yet to implement this, but it is considered a candidate for v3. A feature request with the following code exists at https://github.com/SignalR/SignalR/issues/66

public static class SignalRConnectionToGroupsMap
{
    private static readonly ConcurrentDictionary<string, List<string>>  Map = new ConcurrentDictionary<string, List<string>>();

    public static bool TryAddGroup(string connectionId, string groupName)
    {
        List<string> groups;

        if (!Map.TryGetValue(connectionId, out groups))
        {
            return Map.TryAdd(connectionId, new List<string>() {groupName});
        }

        if (!groups.Contains(groupName))
        {
            groups.Add(groupName);
        }

        return true;
    }

    // since for this use case we will only want to get the List of group names
    // when we're removing the mapping - we might as well remove the mapping while
    // we're grabbing the List
    public static bool TryRemoveConnection(string connectionId, out List<string> result)
    {
        return Map.TryRemove(connectionId, out result);
    }
}

回答2:

As of v0.5.2, there is no way to leave all groups because the server doesn't keep track of the groups a client belongs to. You need to do this yourself and remove the client from each group one-by-one.

There's a request for something similar in the backlog however, so maybe this will be implemented in a future release: https://github.com/SignalR/SignalR/issues/66