# LS2003: WebApi Uses an MVC Controller

## Intent

LS2003 is a compiler check that reports an MVC controller class in the WebApi project. A controller groups several HTTP operations behind shared filters and routing, while the .NET stack gives each operation its own endpoint class, so each route can be read and reviewed on its own. This page states what the rule reports, where the warning sits, and how to replace the controller with endpoints.

## Reference

### What the rule enforces

LS2003 enforces [Exclude MVC controllers from the stack](https://litespec.dev/2.0.0/backend/dotnet/api.md#exclude-mvc-controllers-from-the-stack) (`litespec/backend/dotnet/api#exclude-mvc-controllers-from-the-stack`). It runs in WebApi only. Its category is `LiteSpec.Layers`. It reports a warning and is enabled by default, as the [Analyzers overview](https://litespec.dev/2.0.0/analyzers/README.md) describes.

### What the rule reports

The rule reports a class that derives from `ControllerBase` or `Controller`, directly or through an intermediate base, or that carries the `ApiController` attribute. A class that does both gets one diagnostic. The diagnostic sits on the class name.

### Failing example

```csharp
public sealed class OrdersController : ControllerBase { }
```

### Passing example

```csharp
internal sealed class GetOrderEndpoint : IEndpoint
{
    public void Map() { }
}
```

### How to fix

Map one `IEndpoint` per operation instead of routing through a controller.

## Notes

### What the rule ignores

The rule does not report endpoint classes. It does not run outside WebApi.