How do you send multiple messages with the Azure SignalR Service output binding?

Question

The very first sentence of the doc suggest multiple messages can be sent with the SignalR Service output binding. Link: https://learn.microsoft.com/en-us/azure/azure-functions/functions-bindings-signalr-service-output?tabs=isolated-process%2Cnodejs-v4&pivots=programming-language-csharp

Use the SignalR output binding to send one or more messages

Can you please provide guidance on an appropriate approach to sending multiple messages with an output binding on a function?

I would like to see guidance added to the docs for multiple scenarios, but my specific case details would be:

• Azure Functions v4 isolated
• SignalR service configured in Serverless mode

Answer 1

Figured it out! Create a new POCO and move the output binding from the function to the new return type.

    [Function(nameof(MyFunction))]
    public async Task<SignalRMessages> MyFunction([HttpTrigger(AuthorizationLevel.Anonymous, "post")] HttpRequestData req)
    {
        HttpResponseData response = req.CreateResponse(HttpStatusCode.Accepted);
        SignalRMessageAction[] messages = [
                new SignalRMessageAction(hubActionName, ["TEST1", "TEST1"]),
                new SignalRMessageAction(hubActionName, ["TEST2", "TEST2"])
                ];
        return await Task.FromResult(new SignalRMessages(messages));
    }
    public class SignalRMessages(IEnumerable<SignalRMessageAction> messages)
    {
        [SignalROutput(HubName = hubName, ConnectionStringSetting = appSettingSignalR)]
        public IEnumerable<SignalRMessageAction> Messages { get; set; } = messages;
    }

More detailed answer in this SO answer.

https://stackoverflow.com/a/79281253/7512742

Answer 2

Following-up from the comments, to benefit the community sharing the answer posted by Adam Vincent.

Question/Issue: How do you send multiple messages with the Azure SignalR Service output binding?

Azure doc ref:

Use the SignalR output binding to send one or more messages using Azure SignalR Service.

Copying the solution shared by Adam Vincent (Thank you!)

Answer/solution:

Create a new POCO and move the output binding from the function to the new return type.

[Function(nameof(MyFunction))]
    public async Task<SignalRMessages> MyFunction([HttpTrigger(AuthorizationLevel.Anonymous, "post")] HttpRequestData req)
    {
        HttpResponseData response = req.CreateResponse(HttpStatusCode.Accepted);
        SignalRMessageAction[] messages = [
                new SignalRMessageAction(hubActionName, ["TEST1", "TEST1"]),
                new SignalRMessageAction(hubActionName, ["TEST2", "TEST2"])
                ];
        return await Task.FromResult(new SignalRMessages(messages));
    }
    public class SignalRMessages(IEnumerable<SignalRMessageAction> messages)
    {
        [SignalROutput(HubName = hubName, ConnectionStringSetting = appSettingSignalR)]
        public IEnumerable<SignalRMessageAction> Messages { get; set; } = messages;
    }

Linking Adam's SO post with a detailed answer ( with examples and different methods).

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Please click Accept Answer - it will benefit the community/users to find the answer quickly.