This page explains the advanced features for group channels. Some of them are the premium features available only to a paying user.
endTyping() methods are called while the current user is typing a message in a group channel, the
onTypingStatusUpdated() in the channel event handler will be invoked on all channel members' devices except the one that belongs to the current user.
To keep the most up-to-date and accurate read status of messages for all group channel members, the
markAsRead() method should be called every time one of the members reads messages by entering the channel from a channel list or bringing the opened channel view to the foreground.
If the current user opens a channel and the
markAsReadAll() is called, Sendbird server will update both the unread message count of the individual channel and the total unread message count of all the group channels joined by the user. Then the server triggers the
onReadReceiptUpdated() method of the channel event handler to notify the change of read status to all channel members' devices, except the one that is being used by the current user.
Note: When a channel member sends a message to the channel, Sendbird server updates the member's read receipt to the time when the message has been sent. Meanwhile, the read receipts of other channel members can be updated when the
markAsRead()method is called. If a new member joins the channel, the method works differently based on the value of the
display_past_messageproperty of your Sendbird application. If the property is set to YES, the new member’s read receipt will be updated to the sent time of the last message in the channel. If NO, it will be updated to 0.
display_past_messageproperty determines whether to display past messages to newly joined members when they enter the channel. This property is also linked to the Chat history option, which can be adjusted in the Sendbird Dashboard under Settings > Chat > Channels > Group channels.
You can retrieve the number of members who haven’t received a specific message in a group channel through the
getUndeliveredMembers() method. If zero is returned, it means that the message has been delivered to all members.
getReadMember() method, you can view members who have read a specific message in a group channel. The method returns a list of channel members who have read the message by comparing the message’s creation time and the channel members’ read receipt. The list will exclude the current user and the message sender.
Note: Read receipt indicates the timestamp of the latest time when each user has read messages in the channel, in Unix milliseconds.
If you want to keep track of who has read a new message, we recommend to use the
getReadMembers() method in the
onReadReceiptUpdated() of the channel event handler. Then the client app receives a callback from Sendbird server whenever a channel member reads a message. To do so, you should pass the new message object as an argument to a parameter in the
getReadMembers() method through the
Note: Using the
getUnreadMembers()method, you can also view members who have not read a specific message in a group channel, except the current user and the message sender. In the meantime, you can get information on each channel member's read receipt through the
getUnreadMembers() method, you can get the number of members who have not read a specific message in a group channel. To get the exact value, the channel should be updated first through the
markAsRead() method before calling the
You can retrieve the last message of a group channel.
You can retrieve the total number of the current user's unread messages in a group channel.
You can retrieve the total number of the current user's unread messages in all joined group channels.
You can retrieve the total number of the current user's joined group channels with one or more unread messages.
If you are using the Custom Plan, you can send admin messages to a group channel using the Sendbird Dashboard or Chat Platform API. To send an admin message through your dashboard, go to the Chat > Group channels, select a group channel, find the message box below, click the Admin message tab, and then write your message in the box. An admin message is limited to 1,000 characters.
Unlike other types of messages, a push notification for an admin message is not available by default. If you want assistance on this, contact our sales team.
Note: For clients using the Free Plan, a suggesting message to upgrade to the Custom Plan will be returned when attempting to send an admin message using the Chat Platform API.
You have the option to create further actions in a channel by using extra data in a message. You can add one or more key-values items to a message which you can save, update, or remove, when necessary. Based on those items, you can design and implement several different actions such as measuring user engagement within a chosen time limit through polls or counting how many times a message has been copied by members.
Note: For the quality of performance, every Sendbird application has its own limits to how many key-values items you can add to a single message, as well as the maximum number of values an item can have. If you would like more information on these limits, contact our sales team.
To get the key-values items of a message, read the
The Chat SDK supports the URL link preview when a message text contains the URL of a web page.
Note: This feature is turned ON by default for Sendbird applications created since July 2020. If this isn't available for your Sendbird application, contact our support team to enable the feature.
BaseMessage object includes a valid URL of a website, the object can contain
OGMetaData, a class that holds the OG metadata such as title, URL, description, and default image of an OG object.
Note: Some websites don’t provide the OG metadata. In that case, even though the OG protocol states them as requirements, all of the four properties can be null.
OGImage, the image contained in an
OGMetaData object, is a class that holds image-related data for the
OGImage object. The
OGImage class can also have its own optional structured properties of URL, secure URL, type, width, height, and alt.
Note: Except for width and height, other fields such as URL, secure URL, type, and alt can be null. If the target website doesn’t provide width and height data, the value of those two fields are set to 0.
If a user sends a message with a web page URL and the linked web page possesses Open Graph (OG) tags, or OG metadata, Sendbird server parses the message content, extracts the URL in the message, gets the OG metadata from it, and creates an OG metadata object for the message. Then message recipients will get the parsed message with its OG metadata through the
onMessageReceived() method in the channel event handler of the SDK. On the other hand, the message sender will do the same through the
Displaying an OG metadata object is available for two subtypes of a BaseMessage:
AdminMessage. If the content of either a
AdminMessage object includes a web page URL containing OG metadata, the
onMessageReceived() method returns
If Sendbird server doesn’t have cache memory of the OG metadata of the given URL, the
BaseMessage.ogMetaData can be null due to the time it takes to fetch the OG metadata from a remote web page. In the meantime, the message text containing the URL will be delivered first to message recipients’ client app through the
onMessageReceived() method. When the server completes fetching, the
onMessageUpdated() method will be called and the message with its
OGMetaData object will be delivered to the recipients’ client app. However, if Sendbird server has already cached the OG metadata of the URL, the
BaseMessage.ogMetaData returns the message and its
OGMetaData object instantly and the
onMessageUpdated() method won’t be called.
The following code demonstrates when sending a
UserMessage object with the URL of a web page.
Note: Starting from Flutter Chat SDK 3.1.0, the
The following code demonstrates when receiving a
UserMessage object containing OG metadata.
When creating a group channel, you can additionally specify a custom channel type to subclassify group channels. This custom type takes on the form of a
String, and can be useful in searching or filtering group channels.
customType properties of a channel object allow you to append information to your channels. While both properties can be used flexibly, common examples for the
customType include categorizing group channels into School or Work.
To get a channel's custom type, read the
When sending a message, you can additionally specify a custom message type to subclassify messages. This custom type takes on the form of a
String, and can be useful in searching or filtering messages.
customType properties of a message object allow you to append information to your messages. While both properties can be used flexibly, common examples for the
customType include categorizing message groups into Notes or Contacts.
To embed a custom type into your message, assign a value to the
customType under the
FileMessageParams object. Then, pass the specified object as an argument to the parameter in the
Note: Starting from Flutter Chat SDK 3.1.0, the
To get a message's custom type, read the
You can search for specific group channels by adding keywords to a
GroupChannelListQuery instance. There are three types of keywords: Name, URL and custom type. The code sample below shows the query instance which returns a list of group channels that partially match the specified
Name keyword in the names of the channels.
GroupChannelListQuery instance provides many types of search filters such as
The following shows the query instance which returns a list of group channels that partially match the specified
channelUrls keyword in the URLs of the channels.
customTypes like the following, you can also search for group channels with a specific custom type.
Message search is a feature that retrieves a list of messages that contain a search query or a specified keyword.
MessageSearchQuery to search messages in your app. The query will retrieve a list of messages that contain a search term and meet the optional parameter values set by its properties.
The query will retrieve a list of matched messages. Calling the builder method again will return the next page of the results.
Note: Starting from Flutter Chat SDK 3.1.0, the
hasNext() method to see if there is a next page.
isLoading() method to see if the search results are loading.
You can build the query class by setting the following properties, which allows you to add various search options.
When sending an image file, you can determine whether to create thumbnails of the image, which you can fetch and render into your UI. You can specify up to 3 different dimensions to generate thumbnail images in, which can be useful for supporting various display densities.
Note: Only files whose media type is
video/*are supported. The Chat SDK doesn't support creating thumbnails when sending a file message with a file URL.
sendFileMessage() method requires passing a
FileMessageParams object as an argument to a parameter, containing a list of
thumbnailSizes objects which each specify the maximum values of width and height of a thumbnail image. The
onCompleted callback subsequently returns a list of
Thumbnail objects that each contain the URL of the generated thumbnail image file.
A thumbnail image is generated evenly to fit within the bounds of
maxHeight, which are provided through the constructor. Note that if the original image is smaller than the specified dimensions, the thumbnail isn't resized. The
url returns the location of the generated thumbnail file within Sendbird server.
If needed, you can track the file upload progress by passing the function as an argument to a parameter when calling the
This file encryption feature prevents users without access from opening and reading encrypted files that have been shared within a group of users. When this feature is turned on, all types of sent files and thumbnail images will be first uploaded to Sendbird server, and then encrypted by
In a group channel, encrypted files and thumbnail images will be decrypted and accessed securely only by the members. Anyone outside of the channel and application will not have access to those files and thumbnail images. The following explains how this data security works and what to do at the SDK level to apply it to the client apps.
The Sendbird system enables secure encryption and decryption of files by generating and distributing an opaque and unique encryption key for each user. An encryption key is managed internally by the system, and is valid for 3 days. It is generated every time the user logs in to Sendbird server through the Chat SDK, which then gets delivered to the Chat SDK from the server.
When the Chat SDK requests an encrypted file by its URL, the parameter auth should be added to the URL to access the file, which is specified with an encryption key of the user such as
?auth=RW5jb2RlIHaXMgdGV4eA==. With the specified key in the auth, Sendbird server first decrypts the file, then checks if the user is a member of the group channel, and finally, allows the user to access and open the file in the channel.
This can be easily done by retrieving the
fileMessage.url property, which returns the unique file URL containing the parameter auth with an encryption key of the current user.
This feature allows you to customize the number of messages a participant can send in an open channel per second. By doing so, all excess messages from a participant will be deleted and only the number of messages allowed to be sent per participant per second will be delivered. This feature protects your app from some participants spamming others in the channel with the same messages.
Note: Our default system setting is 5 messages per second. This limit can be manually adjusted only from our side. Contact our sales team for more information.
It is possible for text messages to be sent in different languages through the Sendbird's auto-translation feature. When sending a text message, set a list of language codes to a
UserMessageParams object and then pass the object as an argument to parameter in the
sendUserMessage() method to request translated messages in the corresponding languages.
Note: Message auto-translation is powered by Google Cloud Translation API recognition engine. Find language codes supported by the engine in the Miscellaneous page or visit the Language Support page in Google Cloud Translation.
You can retrieve translations of a text message using the userMessage.translations property which has a NSArray object containing the language codes and translations.
translateUserMessage() method, you can allow your users to translate text messages into other languages when needed.
Note: Message on-demand translation is powered by Google Cloud Translation API recognition engine. Find language codes supported by the engine in the Miscellaneous page or visit the Language Support page in Google Cloud Translation.
Based on this method, you can implement features such as real-time or instant translation to your app. You can also implement to only translate a selected message into preferred languages.