Callback

SimpleW provides a small but powerful set of extension points that allow you to inject logic into the execution flow without modifying the routing or handler model.

These mechanisms are intentionally limited and explicit, to avoid hidden behavior.

OnBeforeMethod

The Controller base class exposes the virtual method OnBeforeMethod().

This method is executed before every controller route method.

Typical use cases include :

• Initializing controller state
• Access checks
• Per-request setup logic

public class TestController : Controller {

    public override void OnBeforeMethod() {
        // executed before each route method
        // example: authentication check
    }

}

Characteristics

• Executed once per request
• Runs after routing, before the handler method
• Applies only to controllers (not delegate-based handlers)

Mental Model

OnBeforeMethod() is a per-controller pre-execution hook.

Controller Subclassing

For cross-cutting controller logic, subclassing Controller is often the cleanest approach.

Instead of duplicating logic across multiple controllers, you can define a shared base class.

Example

public abstract class BaseController : Controller {

    protected void CheckSomething() {
        // shared logic
    }
}

public class UserController : BaseController {

    [Route("GET", "/users")]
    public object Users() {
        CheckSomething();
        return "ok";
    }
}

This approach keeps :

• Business logic explicit
• Controllers focused
• Shared behavior centralized

Excluding Base Controllers from Routing

A base controller may itself define route methods.

If you do not want this class to be registered as a controller, you must explicitly exclude it when mapping controllers.

This avoids unintended routes being exposed.

server.MapControllers<BaseController>("/", exclude: new[] { typeof(BaseController) });

Shared Routes via Base Controllers

If a base controller does define routes, those routes are inherited by subclasses.

Example :

public abstract class BaseController : Controller {

    [Route("GET", "/conf")]
    public object Conf() {
        return "shared config";
    }
}

Accessible as :

• /api/user/conf
• /api/department/conf

Mental Model

Subclassing shares behavior; routing decides visibility.

Choosing the Right Mechanism

Need	Recommended approach
Per-request controller hook	OnBeforeMethod()
Shared controller logic	Base controller subclass
Cross-cutting request logic	Middleware

Callbacks and subclassing complement middleware — they do not replace it.