Using IActionResult with Azure Functions in .NET 5?

Question

After migrating my Azure Functions project to .NET 5, it has started wrapping my responses in a weird wrapper class.

For instance, consider the following endpoint:

public record Response(string SomeValue);

[Function("Get")]
public async Task<IActionResult> Get(
    [HttpTrigger(AuthorizationLevel.Anonymous, "get", Route = "get-something")]
    HttpRequestData request)
{
    return new OkObjectResult(new Response("hello world"));
}

Before, it would return:

{
    "someValue": "hello world"
}

But now, it returns:

{
  "Value": {
    "SomeValue": "hello world"
  },
  "Formatters": [],
  "ContentTypes": [],
  "DeclaredType": null,
  "StatusCode": 200
}

I get that it must be because it just tries to serialize the object result, but I can't find any documentation on how this is supposed to work in .NET 5.

My main function currently looks like this:

public static async Task Main()
{
    var host = new HostBuilder()
        .ConfigureFunctionsWorkerDefaults(x => 
            x.UseDefaultWorkerMiddleware())
        .ConfigureAppConfiguration((_, builder) => builder
            .AddJsonFile("local.settings.json", true)
            .Build())
        .ConfigureServices(ConfigureServices)
        .Build();

    await host.RunAsync();
}

My project is located here, in case someone are interested: https://github.com/sponsorkit/sponsorkit.io

Currently, my .NET 5 work is on a branch called feature/signup-flow.

Answer 1

Using IActionResult with Azure Functions in .NET 5?

You can't return IActionResult with Azure Functions in .NET 5. Or more generally, you can't return IActionResult with Azure Functions using the isolated process model. Quote from the docs:

For HTTP triggers, you must use HttpRequestData and HttpResponseData to access the request and response data. This is because you don't have access to the original HTTP request and response objects when running out-of-process.

Instead of IActionResult, you need to return HttpResponseData. Example code is here.