example: gRPC-compatible controller

as requested at: https://github.com/kataras/iris/issues/1449


Former-commit-id: a0af1a78bcfef85f297c5087c8cbb00124226036

_examples/mvc/grpc-compatible/main.go

@@ -0,0 +1,59 @@
+package main
+
+import (
+	"context"
+
+	"github.com/kataras/iris/v12"
+	"github.com/kataras/iris/v12/mvc"
+)
+
+// See https://github.com/kataras/iris/issues/1449
+// for more details but in-short you can convert Iris MVC to gRPC methods by
+// binding the `context.Context` from `iris.Context.Request().Context()` and gRPC input and output data.
+
+func main() {
+	app := newApp()
+	app.Logger().SetLevel("debug")
+
+	// POST: http://localhost:8080/login
+	// with request data: {"username": "makis"}
+	// and expected output: {"message": "makis logged"}
+	app.Listen(":8080")
+}
+
+func newApp() *iris.Application {
+	app := iris.New()
+
+	mvc.New(app).
+		// Request-scope binding for context.Context-type controller's method or field.
+		// (or import github.com/kataras/iris/v12/hero and hero.Register(...))
+		Register(func(ctx iris.Context) context.Context {
+			return ctx.Request().Context()
+		}).
+		// Bind loginRequest.
+		Register(func(ctx iris.Context) loginRequest {
+			var req loginRequest
+			ctx.ReadJSON(&req)
+			return req
+		}).
+		Handle(&myController{})
+
+	return app
+}
+
+type myController struct{}
+
+type loginRequest struct {
+	Username string `json:"username"`
+}
+
+type loginResponse struct {
+	Message string `json:"message"`
+}
+
+func (c *myController) PostLogin(ctx context.Context, input loginRequest) (loginResponse, error) {
+	// [use of ctx to call a gRpc method or a database call...]
+	return loginResponse{
+		Message: input.Username + " logged",
+	}, nil
+}