Manage channel metadata

You can store additional information to channels such as background color or channel description with channel metadata, which can be fetched or rendered into the UI. Channel metadata is Map<String, String> and it can be stored into a Channel object.

To receive and retrieve information about events happening in channels from the Sendbird server, you can add a channel event handler. For more information on channel event handlers, see Channel event types.

To store channel metadata into a Channel object, create a new object of key-value items in which the data type of the key and value is Map<String, String>. Then, pass the object as an argument to a parameter when calling the createMetaData() method. You can put multiple key-value items in the dictionary.

val data = mapOf("key1" to "value1", "key2" to "value2")
channel.createMetaData(data) { map, e ->
    if (e != null) {
        // Handle error.
    }

    // ...
}

The process of updating channel metadata is the same as creating one. Values of existing keys can be updated and values of new keys can be added by calling the updateMetaData() method.

val data = mapOf(
    "key1" to "valueToUpdate1", // Update an existing item with a new value.
    "key2" to "valueToUpdate2", // Update an existing item with a new value.
    "key3" to "valueToAdd3"     // Add a new key-value item.
)
channel.updateMetaData(data) { map, e ->
    if (e != null) {
        // Handle error.
    }

    // ...
}

You can retrieve channel metadata by creating an List of keys to retrieve and passing it as an argument to a parameter in the getMetaData() method. A Map<String, String> collection will return through the MetaDataHandler callback function with corresponding key-value items.

val keys = listOf("key1", "key2")
channel.getMetaData(keys) { map, e ->
    if (e != null) {
        // Handle error.
    }

    // ...
}

When Sendbird Chat SDK detects any of the create, read, update, and delete operations on the channel metadata, the SDK caches the metadata. The cached metadata is also updated whenever a channel list is fetched.

You can retrieve the cached metadata through the cachedMetaData() method without having to query the server.

val cachedMetaData = channel.cachedMetaData
val value = cachedMetaData[key] // The key should be a string.

You can delete channel metadata by calling the deleteMetaData() method.

channel.deleteMetaData("key1") { e ->
    if (e != null) {
        // Handle error.
    }

    // ...
}