Maple.Result.Extensions.Functions.Worker 0.2.0

Maple.Result.Extensions.Functions.Worker

Maps the Maple.Result to the HTTP response (Azure Functions isolated worker model version)

Project status: EARLY STAGE

Check also my libraries:

• Maple.Result,
• Maple.Result.Extensions.AspNetCore,
• Maple.Result.Extensions.MinimalApi,
• Maple.Result.Extensions.HttpClient.

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Status

✅ Basic mapping without configuration.
✅ Unit and integration tests.
✅ Custom error mapping passed as a parameter to the extension method.
✅ Custom error mapping registered in the service collection.
✅ Support for custom successful status codes.
🔲 Documentation.

Scope

This package targets the Azure Functions isolated worker model with the ASP.NET Core integration disabled, where an HTTP trigger takes an HttpRequestData and returns an HttpResponseData. When the ASP.NET Core integration is enabled, the trigger works with HttpRequest/IActionResult instead, and Maple.Result.Extensions.AspNetCore or Maple.Result.Extensions.MinimalApi applies.

The worker model references neither ASP.NET Core nor its ProblemDetails type, so this package writes the RFC 9457 body itself, with the application/problem+json content type.

Usage

using Maple.Result.Extensions.Functions.Worker;

// Success -> 204 No Content, error -> RFC 9457 problem details
[Function("DeleteOrder")]
public HttpResponseData Delete([HttpTrigger(AuthorizationLevel.Function, "delete", Route = "orders/{id}")] HttpRequestData request, int id)
{
    return orderService.Delete(id).ToHttpResponseData(request);
}

// Success -> 200 OK with the value (204 No Content when the value is null)
[Function("GetOrder")]
public HttpResponseData Get([HttpTrigger(AuthorizationLevel.Function, "get", Route = "orders/{id}")] HttpRequestData request, int id)
{
    return orderService.Get(id).ToHttpResponseData(request);
}

// Success -> the given status code
[Function("CreateOrder")]
public HttpResponseData Create([HttpTrigger(AuthorizationLevel.Function, "post", Route = "orders")] HttpRequestData request, Order order)
{
    return orderService.Create(order).ToHttpResponseData(request, HttpStatusCode.Created);
}

// Success -> mapped explicitly, e.g. to return the Location header
[Function("CreateOrderWithLocation")]
public HttpResponseData CreateWithLocation([HttpTrigger(AuthorizationLevel.Function, "post", Route = "orders")] HttpRequestData request, Order order)
{
    return orderService.Create(order).ToHttpResponseData(request, (Order created, HttpRequestData req) =>
    {
        var response = Result<Order>.FromValue(created).ToHttpResponseData(req, HttpStatusCode.Created);
        response.Headers.Add("Location", $"orders/{created.Id}");

        return response;
    });
}

// Errors -> mapped explicitly; the default mapping is used when the mapping returns null
[Function("ListOrders")]
public HttpResponseData List([HttpTrigger(AuthorizationLevel.Function, "get", Route = "orders")] HttpRequestData request)
{
    return orderService.GetAll().ToHttpResponseData(request,
        (error, req) => error.Category == ErrorCategory.Conflict ? req.CreateResponse(HttpStatusCode.Gone) : null);
}

Custom error mappings can also be registered once for the whole worker. They are evaluated after the mapping passed to the extension method, and in the order they were added:

var builder = FunctionsApplication.CreateBuilder(args);

builder.Services.ConfigureResultMapping(options =>
        options.ErrorMappings.Add((error, request) => error.Category == ErrorCategory.Conflict
            ? request.CreateResponse(HttpStatusCode.Gone)
            : null));

await builder.Build().RunAsync();

Example Error Response

Example

{
    "type": "https://example.com/probs/out-of-credit",
    "title": "You do not have enough credit.",
    "status": 400,
    "detail": "Your current balance is 30, but that costs 50.",
    "instance": "/accounts/12345/msgs/abc",
    "errors": [
        {
            "pointer": "#/age",
            "detail": "must be a positive integer",
            "detailTemplated": {
                "templateId": "user.details.age.mustBePositive"
            }
        },
        {
            "pointer": "#/profile/colour",
            "detail": "must be ‘green’, ‘red’ or ‘blue’",
            "detailTemplated": {
                "templateId": "user.profile.colour",
                "params": {
                    "validValueIds": [
                        "user.profile.colour.green",
                        "user.profile.colour.red",
                        "user.profile.colour.blue"
                    ]
                }
            }
        }
    ],
    "detailTemplated": {
        "templateId": "user.account.balance.tooLow",
        "params": {
            "errorCode": "UAB17",
            "accounts": [
                {
                    "title": "Main (***9456)",
                    "url": "/accounts/12345"
                },
                {
                    "title": "Main (***3357)",
                    "url": "/accounts/67890"
                }
            ],
            "currentBalance": 30,
            "requiredBalance": 50
        }
    }
}

Unlike the ASP.NET Core versions, the response carries no traceId extension: the isolated worker model has no equivalent of the ASP.NET Core Problem Details service adding it.

See also

• Problem Details for HTTP APIs - RFC 7807 is dead, long live RFC 9457
• tag URI scheme
• RFC 1738: Uniform Resource Locators (URL)
• RFC 3986: Uniform Resource Identifier (URI): Generic Syntax
• RFC 4151: The 'tag' URI Scheme
• RFC 6901: JavaScript Object Notation (JSON) Pointer
• RFC 9457: Problem Details for HTTP APIs

Contribution

Please contact author: engineer(at sign)blumail(dot)me