ASP.NET Core Web API Interview Question #104

Should a controller contain business logic?

Dependency Injection, Services, EF Core, Async & Data Access Mid-Level Intermediate

Quick Interview Answer

Controllers should mainly coordinate HTTP concerns: accept input, invoke application services, apply endpoint-level authorization, and translate outcomes into HTTP responses. Complex business workflows should generally live in application or domain services.

Detailed Explanation

Thin controllers improve testability and reduce duplication because the same business operation can be reused from other entry points without depending on ControllerBase.

Code Example

[HttpPost]
public async Task<ActionResult<OrderResponse>> Create(
    CreateOrderRequest request,
    CancellationToken token)
{
    var result = await _orderService.CreateAsync(request, token);
    return CreatedAtAction(nameof(Get), new { id = result.Id }, result);
}