CODEWITHSUNDEEP
azure-functions
Bjorn Reppen
Bjorn Reppen

Reputation: 22769

Which exception to throw to return HTTP status code in Azure HttpTrigger Function

In a C# Azure function what Exception classes can be thrown to cause specific HTTP status codes to be returned from the API. For example a "404 Not Found" when a key lookup in an in-memory structure has no hits.

I would like to avoid returning codes up the stack when we have exceptions available that were created for this purpose.

Upvotes: 2

Views: 1050

Answers (1)

theblindprophet
theblindprophet

Reputation: 7927

There appears to be two ways to do this, however, one is in preview.

Preview:

https://github.com/Azure/azure-webjobs-sdk/wiki/Function-Filters

Middlware:

If you run your Azure function as an isolated process you can add your own custom middleware which could take care of exception handling.

https://learn.microsoft.com/en-us/azure/azure-functions/dotnet-isolated-process-guide#middleware

// Source above
var host = new HostBuilder()
    .ConfigureFunctionsWorkerDefaults(workerApplication =>
    {
        // Register our custom middlewares with the worker

        workerApplication.UseMiddleware<ExceptionHandlingMiddleware>();

        workerApplication.UseMiddleware<MyCustomMiddleware>();

        workerApplication.UseWhen<StampHttpHeaderMiddleware>((context) =>
        {
            // We want to use this middleware only for http trigger invocations.
            return context.FunctionDefinition.InputBindings.Values
                          .First(a => a.Type.EndsWith("Trigger")).Type == "httpTrigger";
        });
    })
    .Build();

In doing so you would need to then return HttpResponseData object.

https://learn.microsoft.com/en-us/azure/azure-functions/dotnet-isolated-process-guide#differences-with-net-class-library-functions

Upvotes: 1

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