Extensions

SDK Method Names

Use x-fern-sdk-method-name to customize SDK method names for operations

By default, Fern generates SDK method names based on your operation names in AsyncAPI. You can override this behavior using the x-fern-sdk-method-name extension.

Customize operation method names

Use x-fern-sdk-method-name to specify custom method names for your operations:

asyncapi.yml
1operations:
2  subscribeToUserEvents:
3    action: receive
4    channel:
5      $ref: '#/channels/user~1events'
6    x-fern-sdk-method-name: onUserEvent
7    summary: Subscribe to user events
8  publishOrderUpdate:
9    action: send
10    channel:
11      $ref: '#/channels/order~1updates'
12    x-fern-sdk-method-name: sendOrderUpdate
13    summary: Publish order update

This will generate SDK methods like:

1// Instead of client.subscribeToUserEvents()
2client.onUserEvent((event) => {
3  // Handle user event
4});
5
6// Instead of client.publishOrderUpdate()
7client.sendOrderUpdate(orderData);

Method naming conventions

Follow these conventions when naming SDK methods:

Subscribe operations

Use descriptive names that indicate the action:

asyncapi.yml
1operations:
2  subscribeToNotifications:
3    action: receive
4    x-fern-sdk-method-name: onNotification
5    # Generates: client.onNotification()
6    
7  subscribeToOrderUpdates:
8    action: receive
9    x-fern-sdk-method-name: watchOrders
10    # Generates: client.watchOrders()

Publish operations

Use action-oriented names:

asyncapi.yml
1operations:
2  publishUserSignup:
3    action: send
4    x-fern-sdk-method-name: createUser
5    # Generates: client.createUser()
6    
7  publishNotification:
8    action: send
9    x-fern-sdk-method-name: notify
10    # Generates: client.notify()

Language-specific method names

You can specify different method names for different programming languages:

asyncapi.yml
1operations:
2  subscribeToEvents:
3    action: receive
4    channel:
5      $ref: '#/channels/events'
6    x-fern-sdk-method-name:
7      python: on_event
8      typescript: onEvent
9      go: OnEvent
10      java: onEvent
11      csharp: OnEvent

This ensures method names follow the conventions of each target language.