Name: ErrorOrX.Generators
Author: ANcpLua

./nugetz

ErrorOrX.Generators v3.0.1 — nugetz

[Authorize]

[EnableRateLimiting]

[OutputCache]

dotnet add package ErrorOrX.Generators

// Program.cs
var app = WebApplication.CreateSlimBuilder(args).Build();
app.MapErrorOrEndpoints();
app.Run();

// TodoApi.cs
using ErrorOr;

public static class TodoApi
{
    [Get("/todos/{id}")]
    public static ErrorOr<Todo> GetById(int id, ITodoService svc)
        => svc.GetById(id).OrNotFound($"Todo {id} not found");

    [Post("/todos")]
    public static ErrorOr<Todo> Create(CreateTodoRequest req, ITodoService svc)
        => svc.Create(req);  // 201 Created

    [Delete("/todos/{id}")]
    public static ErrorOr<Deleted> Delete(int id, ITodoService svc)
        => svc.Delete(id) ? Result.Deleted : Error.NotFound();
}

Error.Validation("User.InvalidEmail", "Email format is invalid")   // 400
Error.Unauthorized("Auth.InvalidToken", "Token has expired")       // 401
Error.Forbidden("Auth.InsufficientRole", "Admin role required")    // 403
Error.NotFound("User.NotFound", "User does not exist")             // 404
Error.Conflict("User.Duplicate", "Email already registered")       // 409
Error.Failure("Db.ConnectionFailed", "Database unavailable")       // 500
Error.Unexpected("Unknown", "An unexpected error occurred")        // 500
Error.Custom(422, "Validation.Complex", "Complex validation failed")

// Error code auto-generated from type name (e.g., "Todo.NotFound")
return _todos.Find(t => t.Id == id).OrNotFound($"Todo {id} not found");
return user.OrUnauthorized("Invalid credentials");
return record.OrValidation("Record is invalid");

// Custom errors
return value.OrError(Error.Custom(422, "Custom.Code", "Custom message"));
return value.OrError(() => BuildExpensiveError());  // Lazy evaluation

Extension	Error Type	HTTP	Description
`.OrNotFound()`	NotFound	404	Resource not found
`.OrValidation()`	Validation	400	Input validation failed
`.OrUnauthorized()`	Unauthorized	401	Authentication required
`.OrForbidden()`	Forbidden	403	Insufficient permissions
`.OrConflict()`	Conflict	409	State conflict
`.OrFailure()`	Failure	500	Operational failure
`.OrUnexpected()`	Unexpected	500	Unexpected error
`.OrError(Error)`	Any	Any	Custom error
`.OrError(Func)`	Any	Any	Lazy custom error

// Chain operations - errors short-circuit the pipeline
var result = ValidateOrder(request)
    .Then(order => ProcessPayment(order))
    .Then(order => CreateShipment(order))
    .FailIf(order => order.Total <= 0, Error.Validation("Order.InvalidTotal", "Total must be positive"));

// Handle both cases
return result.Match(
    order => Ok(order),
    errors => BadRequest(errors.First().Description));

// Provide fallback on error
var user = GetUser(id).Else(errors => DefaultUser);

// Side effects
GetUser(id).Switch(
    user => Console.WriteLine($"Found: {user.Name}"),
    errors => Logger.LogError(errors.First().Description));

Result.Success   // 200 OK (no body)
Result.Created   // 201 Created (no body)
Result.Updated   // 204 No Content
Result.Deleted   // 204 No Content

[Post("/todos")]
public static ErrorOr<Todo> Create(
    CreateTodoRequest req,    // -> Body (POST + complex type)
    ITodoService svc)         // -> Service (interface)
    => svc.Create(req);

[Get("/todos/{id}")]
public static ErrorOr<Todo> GetById(
    int id,                   // -> Route (matches {id})
    ITodoService svc)         // -> Service
    => svc.GetById(id).OrNotFound();

[Post("/admin")]
[Authorize("Admin")]
[EnableRateLimiting("fixed")]
[OutputCache(Duration = 60)]
public static ErrorOr<User> CreateAdmin(CreateUserRequest req) { }
// Generates: .RequireAuthorization("Admin").RequireRateLimiting("fixed").CacheOutput(...)

var builder = WebApplication.CreateSlimBuilder(args);

builder.Services.AddErrorOrEndpoints(options => options
    .UseJsonContext<AppJsonSerializerContext>()  // Register JSON context
    .WithCamelCase()                              // Use camelCase (default: true)
    .WithIgnoreNulls());                          // Ignore nulls (default: true)

var app = builder.Build();
app.MapErrorOrEndpoints();
app.Run();

[JsonSourceGenerationOptions(
    PropertyNamingPolicy = JsonKnownNamingPolicy.CamelCase,
    DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull)]
[JsonSerializable(typeof(Todo))]
[JsonSerializable(typeof(CreateTodoRequest))]
[JsonSerializable(typeof(ProblemDetails))]
internal partial class AppJsonSerializerContext : JsonSerializerContext;

<PropertyGroup>
    <ErrorOrGenerateJsonContext>false</ErrorOrGenerateJsonContext>
</PropertyGroup>

Package	Target	Description
`ErrorOrX.Generators`	`netstandard2.0`	Source generator (includes ErrorOrX)
`ErrorOrX`	`net10.0`	Runtime library (auto-referenced)

ANcpLua/ErrorOrX.Generatorsv3.0.1

Get Started

Readme

ErrorOrX

Features

Installation

Quick Start

Error Types

Nullable-to-ErrorOr Extensions

Fluent API

Result Markers

Smart Parameter Binding

Middleware Attributes

Native AOT

Packages

Documentation