Querying Channels

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Last Edit: Jan 14 2021

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If you’re building a similar application to Facebook Messenger or Intercom, you’ll want to show a list of Channels. The Chat API supports MongoDB style queries to make this easy to implement.

You can query channels based on built-in fields as well as any custom field you add to channels. Multiple filters can be combined using AND, OR logical operators, each filter can use its comparison (equality, inequality, greater than, greater or equal, etc.). You can find the complete list of supported operators in the query syntax section of the docs.

As an example, let's say that you want to query the last conversations I participated in sorted by last_message_at.

Stream Chat does not run MongoDB on the backend, only a subset of the query options are available.

Here’s an example of how you can query the list of channels:


const filter = { type: 'messaging', members: { $in: ['thierry'] } };
const sort = { last_message_at: -1 };

const channels = await authClient.queryChannels(filter, sort, {
    watch: true, // this is the default
    state: true,
});

for (const c of channels) {
    console.log(c.custom.name, c.cid);
}


final filter = {
  "type": "messaging",
  "members": {
    "\$in": ["thierry"]
  }
};

final sort = [SortOption("last_message_at", direction: SortOption.DESC)];

final channels = await client.queryChannels(
  filter: filter,
  sort: sort,
  options: {
    "watch": true, 
    "state": true,
  },
).last;

channels.forEach((Channel c) {
  print("${c.extraData['name']} ${c.cid}");
});


$filter  = ['members' => ['$in' => ['elon', 'jack', 'jessie'] ]];
$sort    = ['last_message_at' => 1]; // sorting direction (1 or -1)
$options = ['limit' => 10];

$channels = $client->queryChannels($filter,$sort,$options);


val filter = Filters.`in`("members", "thierry").put("type", "messaging")
val offset = 0
val limit = 10
val sort = QuerySort().desc("last_message_at")
val request = QueryChannelsRequest(filter, offset, limit, sort)
request.watch = true
request.state = true

client.queryChannels(request).enqueue {
    val channels = it.data()
}


let query = ChannelsQuery(filter: .equal("type", to: "messaging") & .in("members", ["thierry"]),
                          sort: [.init("last_message_at", isAscending: false)],
                          pagination: [.limit(10)])
Client.shared.queryChannels(query: query) { (result) in
    // handle result
}

Query Parameters

Name	Type	Description	Default
filters	object	The query filters to use. You can query on any of the custom fields you've defined on the Channel. You can also filter other built-in channel fields, see next section for reference.	{}
sort	objects	The sorting used for the channels matching the filters. Sorting is based on field and direction, multiple sorting options can be provided. You can sort based on last_updated, last_message_at, updated_at, created_at, member_count, unread_count or has_unread(unread status). Direction can be ascending (1) or descending (-1)	{last_updated: -1}
options	object	Query options. See below.	{}

By default when query channels does not have any filter and it will match all channels on your application. While this might be OK during development, you most likely want to have at least some basic filtering.

At a minimum, the filter should include members: { $in: [userID] } .

The query channels endpoint will only return channels that the user can read, you should make sure that the query uses a filter that includes such logic. For example: messaging channels are readable only to their members, such requirement can be included in the query filter (see below).

Common filters by use-case

Messaging and Team

On messaging and team applications you normally have users added to channels as a member. A good starting point is to use this filter to show the channels the user is participating.


const filter = { members: { $in: ['thierry'] } };


final filter = {
  "type": "messaging",
  "members": {
    "\$in": ["thierry"],
  }
};


$filter  = ['members' => ['$in' => ['thierry'] ]];


val filter = Filters
        .`in`("members", "thierry")
        .put("type", "messaging")


let filter = Filter.currentUserInMembers
// or
let filter = Filter.in("members", [User.current.id])
// or
let filter = Filter.in("members" ["thierry"])

Support

On a support chat, you probably want to attach additional information to channels such as the support agent handling the case and other information regarding the status of the support case (ie. open, pending, solved).


const filter = { agent_id: `${user.Id}`, status: { $in: ['pending', 'open', 'new'] }};


final filter = {
  "agent_id": "${user.id}",
  "status": {
    "\$in": ['pending', 'open', 'new'],
  }
};


$filter  = ['agent_id' => 'agent-id', 'status' => ['$in' => ['pending', 'open', 'new'] ]];


val filter = Filters
    .`in`("status", "pending", "open", "new")
    .put("agent_id", userId)


let filter = Filter.equal("agent_id", to: User.current.id) & .in("status", ["pending", "open", "new"])

Channel Queryable Built-In Fields

The following channel fields can be used to filter your query results

Name	Type	Description	Example
frozen	boolean	channel frozen status	false
type	string	the type of channel	messaging
id	string	the ID of the channel	general
cid	string	the full channel ID	messaging:general
members	string or list of string	the list of user IDs of the channel members	marcelo or [thierry, marcelo]
invite	string, must be one of these values: (pending, accepted, rejected)	the status of the invite	pending

Querying by the channel Identifier should be done using the cid field as far as possible to optimize API performance. As the full channel ID, cidis indexed everywhere in Stream database where id is not.

Query Options

Name	Type	Description	Default	Optional
state	boolean	if true returns the Channel state	true	✓
watch	boolean	if true listen to changes to this Channel in real time.	false	✓
limit	integer	The number of channels to return (max is 30)	10	✓
offset	integer	The offset (max is 1000)	0	✓
message_limit	integer	How many messages should be included to each channel	25	✓
member_limit	integer	How many members should be included to each channel	100	✓

Query channels allows you to retrieve channels and start watching them at same time using the watch parameter set to true.

Response

The result of querying a channel is a list of ChannelState objects which include all the required information to render them without any additional API call.

ChannelState Response

Field Name	Description
channel	The data for this channel
messages	The most recent messages for this channel (see message_limit option)
watcher_count	How many users are currently watching the channel
read	The read state for all members of the channel
members	The list of members, up to 100 ordered by the most recent added
pinned_messages	Up to 10 most recent pinned messages

The event system ensures that your local copy of the channel state stays up to date.

Although the watcher count can be obtained through this method, a list of watchers cannot be. For that, you will need to use channel.query( { watchers: { limit: 20, offset: 0 } });. See more here.

Channel state is immutable. It leverages seamless-immutable to prevent bugs caused by accidentally editing state.

Query channel requests can be paginated similar to how you paginate on other calls. Here's a short example:


// retrieve 20 channels with Thierry as a member and skip first 10

const filter = { members: { $in: ['thierry'] } };
const sort = { last_message_at: -1 };

const channels = await authClient.queryChannels(filter, sort, {
    limit: 20, offset: 10
});


// retrieve 20 channels with Thierry as a member and skip first 10

final filter = {
  "members": {
    "\$in": ['thierry'],
  }
};

final sort = [SortOption("last_message_at", direction: SortOption.DESC)];

final response = await client.queryChannels(
  filter: filter,
  sort: sort,
  options: {
    "limit": 20,
    "offset": 10,
  },
);

response.channels.forEach((ChannelState f) {
  print("${f.channel.extraData['name']} ${f.channel.cid}");
});


// retrieve 20 channels with Thierry as a member and skip first 10
$filter  = ['members' => ['$in' => ['thierry'] ]];
$sort    = ['last_message_at' => -1]; // sorting direction (1 or -1)
$options = ['limit' => 20, 'offset' => 10];

$channels = $client->queryChannels($filter,$sort,$options);


val filter = Filters.`in`("members", "thierry")
val offset = 0
val limit = 10
val request = QueryChannelsRequest(filter, offset, limit)

client.queryChannels(request).enqueue {
    val channels = it.data()
}


let channel = Client.shared.channel(type: .messaging, id: "general")

let query = ChannelQuery(channel: channel,
                         messagesPagination: [.limit(2), .lessThanOrEqual("123")],
                         membersPagination: [.limit(2)],
                         watchersPagination: [.limit(2)])
    
Client.shared.queryChannel(query: query) { (result) in
    // handle result
}

// or

channel.query(messagesPagination: [.limit(2), .lessThanOrEqual("123")],
              membersPagination: [.limit(2)],
              watchersPagination: [.limit(2)]) { result in /* Handle result */ }

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