Send a message

For both open and group channels, users can send messages of the following types to the channel they are in.

Message type	Class	Description
Text	UserMessage	A text message sent by a user.
File	FileMessage	A binary file message sent by a user.
File	MultipleFilesMessage	A message with multiple files sent by a user.

In addition to these message types, you can further subclassify a message by specifying its custom type. This custom type takes on the form of String and can be used to search or filter messages. It allows you to append information to your message and customize message categorization.

The following code shows several types of parameters that you can configure to customize text messages using UserMessageCreateParams. Under the UserMessageCreateParams object, you can assign specific values to message, data, and other properties. By assigning arbitrary string to the data property, you can set custom font size, font type, or JSON object. To send your messages, you need to pass the UserMessageCreateParams object as an argument to the parameter in the sendUserMessage() method.

Through the callback handler of the sendUserMessage() method, the Sendbird server always notifies whether your message has been successfully sent to the channel. When there is a delivery failure due to network issues, an exception is returned through the callback method.

Kotlin

val userIdsToMention = listOf("Jeff", "Julia")
val targetLanguages = listOf("fr", "de") // French, German
val params = UserMessageCreateParams(TEXT_MESSAGE).apply {
    customType = CUSTOM_TYPE
    data = DATA
    mentionType = MentionType.USERS
    mentionedUserIds = userIdsToMention
    metaArrays = listOf(
        MessageMetaArray("itemType", listOf("tablet")),
        MessageMetaArray("quality", listOf("best", "good"))
    )
    translationTargetLanguages = targetLanguages
    pushNotificationDeliveryOption = PushNotificationDeliveryOption.DEFAULT
}
channel.sendUserMessage(params) { message, e ->
    if (e != null) {
        // Handle error.
    }

    // A text message with detailed configuration is successfully sent to the channel.
    // By using message.messageId, message.message, message.customType, and so on,
    // you can access the result object from the Sendbird server to check your UserMessageCreateParams configuration.
    // The current user can receive messages from other users through the onMessageReceived() method of an event handler.
}

A user can also send a binary file through the Chat SDK as the file itself or through sending a URL.

Sending a raw file means you're uploading it to the Sendbird server where it can be downloaded on client apps. When you upload a file directly to the server, there is a size limit imposed on the file depending on your plan. You can see the limit on your dashboard and contact our sales team to change the limit.

The other option is to send a file hosted on your server. You can pass the file's URL, which represents its location, as an argument to a parameter. In this case, your file isn't hosted on the Sendbird server and it can only be downloaded from your own server. When you send a file message with a URL, there is no limit on the file size since it isn't directly uploaded to the Sendbird server.

Note: You can use sendFileMessages(), which is another method that allows you to send up to 20 file messages per one method call. Refer to our API Reference to learn more.

The following code shows several types of parameters that you can configure to customize file messages by using FileMessageCreateParams. Under the FileMessageCreateParams object, you can assign specific values to customType and other properties. To send your messages, you need to pass the FileMessageCreateParams object as an argument to the parameter in the sendFileMessage() method.

Through the callback handler of the sendFileMessage() method, the Sendbird server always notifies whether your message has been successfully sent to the channel. When there is a delivery failure due to network issues, an exception is returned through the callback method.

Kotlin

// Send a file message with a raw file.
// Create and add a ThumbnailSize object.
// Up to three thumbnail images are allowed.
val thumbnailSizeList = listOf(
    ThumbnailSize(100, 100),
    ThumbnailSize(200, 200)
)

val userIdsToMention = listOf("Jeff", "Julia")
val params = FileMessageCreateParams().apply {
    file = FILE // Or fileUrl = FILE_URL
    fileName = FILE_NAME
    fileSize = FILE_SIZE
    mimeType = MIME_TYPE
    thumbnailSizes = thumbnailSizeList
    customType = CUSTOM_TYPE
    mentionType = MentionType.USERS      // Either USERS or CHANNEL
    mentionedUserIds = userIdsToMention  // Or mentionedUsers = LIST_OF_USERS_TO_MENTION
    pushNotificationDeliveryOption = PushNotificationDeliveryOption.DEFAULT  // Either DEFAULT or SUPPRESS
}
channel.sendFileMessage(params) { message, e ->
    if (e != null) {
        // Handle error.
    }

    // A file message with detailed configuration is successfully sent to the channel.
    // By using message.messageId, message.fileName, message.customType, and so on,
    // you can access the result object from the Sendbird server to check your FileMessageCreateParams configuration.
    // The current user can receive messages from other users through the onMessageReceived() method of an event handler.
}

You can also send a message with multiple files through sendMultipleFilesMessage() by passing an MultipleFilesMessageCreateParams object. The params contains uploadableFileInfoList, which holds an array of uploadableFileInfo objects. A single uploadableFileInfo object contains the data of each file such as fileUrl and fileSize.

Kotlin

// Send a file message with a raw file.
// Create and add a ThumbnailSize object.
// Up to three thumbnail sizes are allowed.
val thumbnailSizeList = listOf(
    ThumbnailSize(100, 100),
    ThumbnailSize(200, 200)
)
val uploadableFileInfo = UploadableFileInfo(
    file = FILE,
    fileName = FILE_NAME,
    fileSize = FILE_SIZE,
    fileType = MIME_TYPE,
    thumbnailSizes = thumbnailSizeList
)
val uploadableFileInfo2 = UploadableFileInfo(
    file = FILE_2,
    fileName = FILE_NAME_2,
    fileSize = FILE_SIZE_2,
    fileType = MIME_TYPE_2,
    thumbnailSizes = thumbnailSizeList
)
val uploadableFileInfoList = listOf(
    uploadableFileInfo,
    uploadableFileInfo2
)
val params = MultipleFilesMessageCreateParams(uploadableFileInfoList).apply {
    customType = CUSTOM_TYPE
    mentionType = MentionType.USERS      // Either USERS or CHANNEL
    mentionedUserIds = userIdsToMention  // Or mentionedUsers = LIST_OF_USERS_TO_MENTION
    pushNotificationDeliveryOption = PushNotificationDeliveryOption.DEFAULT  // Either DEFAULT or SUPPRESS
}

channel.sendMultipleFilesMessage(params) { message, e ->
    if (e != null) {
        // Handle error.
    }

    // A multiple files message with detailed configuration is successfully sent to the channel.
    // By using message.messageId, message.files, message.customType, and so on,
    // you can access the result object from the Sendbird server to check your MultipleFilesMessageCreateParams configuration.
    // The current user can receive messages from other users through the onMessageReceived() method of an event handler.
}

Once all of the files are uploaded to the Sendbird server and its message is successfully sent, file-related data is contained in the message object's files as an array of UploadedFileInfo.

If some files fail to upload while others succeed, the message is marked as failed and the server returns the URL of successfully uploaded files in a failed message through onResult(). You could use the URLs when retrying the message request.

Sample app