web-api

ASP.NET Core Web API

Trigger On

• working on controller-based APIs in ASP.NET Core
• needing controller-specific extensibility or conventions
• migrating or reviewing existing API controllers and filters

Workflow

1. Use controllers when the API needs controller-centric features, not simply because older templates did so.
2. Keep controllers thin: map HTTP concerns to application services or handlers, and avoid embedding data access and business rules directly in actions.
3. Use clear DTO boundaries, explicit validation, and predictable HTTP status behavior.
4. Review authentication and authorization at both controller and endpoint levels so the API surface is not accidentally inconsistent.
5. Keep OpenAPI generation, versioning, and error contract behavior deliberate rather than incidental.
6. Use minimal-apis for new simple APIs instead of defaulting to controllers out of habit.

Current Upstream Notes

• dotnet/aspnetcore v10.0.11 is servicing and updates the OpenAPI stack to 2.7.5; controller-based API guidance still depends on conventions, advanced model binding, OData, JsonPatch, and existing filters. Re-run generated-document and client contract checks after upgrading.
• The August 2026 aspnetcore-10.0 overview keeps controller APIs alongside Minimal APIs rather than replacing them. Use the dedicated routing, OpenAPI, auth, and hosting pages before changing public API contracts.

Deliver

• controller APIs with explicit contracts and policies
• reduced controller bloat
• tests or smoke checks for critical API behavior

Validate

• controller features are actually justified
• actions do not hide business logic and persistence details
• HTTP semantics stay predictable across endpoints

Controller Structure

Use primary constructors (C# 12+) for dependency injection and keep controllers focused on HTTP concerns:

[ApiController]
[Route("api/[controller]")]
public class OrdersController(
    IOrderService orderService,
    ILogger<OrdersController> logger) : ControllerBase
{
    [HttpGet("{id:guid}")]
    [ProducesResponseType<OrderDto>(StatusCodes.Status200OK)]
    [ProducesResponseType(StatusCodes.Status404NotFound)]
    public async Task<IActionResult> GetById(Guid id, CancellationToken ct)
    {
        var order = await orderService.GetByIdAsync(id, ct);
        return order is null ? NotFound() : Ok(order);
    }

    [HttpPost]
    [ProducesResponseType<OrderDto>(StatusCodes.Status201Created)]
    [ProducesResponseType<ValidationProblemDetails>(StatusCodes.Status400BadRequest)]
    public async Task<IActionResult> Create(CreateOrderRequest request, CancellationToken ct)
    {
        var order = await orderService.CreateAsync(request, ct);
        return CreatedAtAction(nameof(GetById), new { id = order.Id }, order);
    }
}