SDKsFlutter

Create a custom message

Create a structured application-defined message with the OpenIM Flutter SDK.

Encapsulate application-specific custom data structures (such as polls, red packets, or order cards) into a message object ready for delivery:

Parameters

Parameter	Type	Required	Description
`data`	`String`	Yes	Core custom payload, typically formatted as a JSON string.
`extension`	`String`	Yes	Custom extension string, commonly used to identify schema namespaces or protocol versions.
`description`	`String`	Yes	Plain text summary of the custom message, used for offline push notifications or fallback UI rendering.

Code example

final message = await OpenIM.iMManager.messageManager.createCustomMessage(
  data: jsonEncode({'version': 1, 'orderID': orderID}),
  extension: jsonEncode({'schema': 'com.example.order'}),
  description: 'Order card',
);

Recipients should validate the payload structure and schema version upon decoding. Authoritative business state must remain on your application backend; custom messages serve as delivery carriers.

Return value

Returns a Future resolving to a custom Message object ready for transmission. Its custom data is stored in customElem.

State changes after the call

Creating a message only constructs the local message data structure in memory; it does not perform network transmission and does not trigger new-message event callbacks. Once constructed, pass the returned Message instance to Send a message to deliver it to a direct or group conversation.

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