Retrieve a list of channels

You can retrieve a list of OpenChannel objects using the next() method of an OpenChannelListQuery instance.

On the other hand, a list of GroupChannel objects can be retrieved through GroupChannelCollection and its loadMore() method. First, create a GroupChannelListQuery instance. The GroupChannelListQuery instance returns both public and private group channels that the current user has joined. To retrieve a list of certain group channels such as public group channels or Supergroup channels, use the the list query's filters as described at the bottom of this page.

Note: You can also search for specific open channels and group channels with keywords and filters.

Create an OpenChannelListQuery instance to retrieve a list of open channels matching the specifications set by OpenChannelListQuery. After a list of open channels is successfully retrieved, you can access the data of each open channel from the result list through the openChannel parameter of the callback method.

try {
  final query = OpenChannelListQuery()
    ..channelUrl = channel.channelUrl;

  final openChannels = await query.next();
  // A list of open channels is successfully retrieved.
} catch (e) {
  // Handle error.
}

A group channel list view can be drawn with a GroupChannelCollection instance. First, create a GroupChannelListQuery instance. This determines which channel to include in the channel list and how to list channels in order.

To retrieve group channels in the collection, call hasMore first to check whether there are more channels to load for the collection. If so, call loadMore().

To learn more about how the collection works, see Group channel collection under Local caching.

try {
  // Check whether there are more channels to load before calling loadMore().
  if (collection.hasMore) {
      await collection.loadMore();
  }
} catch (e) {
  // Handle error.
}

When creating a GroupChannelCollection instance, you need to set params within GroupChannelListQuery first. The params in GroupChannelListQuery works much like other search options, retrieving a list of group channels matching the specifications set by properties in the query instance. For example, use myMemberStateFilter when searching for only the group channels that the current user belongs to, and publicChannelFilter when searching for all public group channels regardless of the current user's membership status. To retrieve a list of Supergroup channels, you can set the superChannelFilter property to SuperChannelFilter.superChannelOnly.

Once the params is set, you can use the query instance for query parameter in GroupChannelCollection constructor.

// Create a GroupChannelListQuery instance.
final query = GroupChannelListQuery()
  ..includeEmpty = true // The default value is true.
  ..order = GroupChannelListQueryOrder.chronological // Acceptable values are chronological, latestLastMessage(default), channelNameAlphabetical and metadataValueAlphabetical.
  ..publicChannelFilter = PublicChannelFilter.public // Retrieve public group channels.
  ..superChannelFilter = SuperChannelFilter.superChannelOnly; // Retrieve Supergroup channels.
  // You can add other params setters.

This table only contains properties shown in the code above. To see the comprehensive list of all available methods and properties, see GroupChannelListQuery in API reference.