make a instance of a struct by string

i am building a app and i want to use a simple mvc model in it

i have a package controllers with in there controller structs like this

type UserController struct {}

func (u *UserController) Index(res http.ResponseWriter, req http.Request) {
  // some code in it
}

what i want to achieve is that i can make instance of that controller by string like

func NewAppController("user") { }

so i can dynamicly create instances of my controllers by my route requests

an other way i think about is to map my controllers like this

var controllerProvider = map[string]interface{} {
   "user": &controllers.UserController{},
   "warehouse": &controllers.WarehouseController{},
 }

and then call it by

appController = mux.Vars(req)["controller"]
c := controllerProvider[appController]

but i rather use the first way any idea how to deal with this?

You could try to create a new object that implements reflect.Type interface and then use it through reflect's mechanisms, but it looks like a complete waste of time. Instead, consider these alternatives:

• Make a struct with fields like Name string and Methods map[string]ActionFunc. This would work, but it doesn't look very idiomatic to me. (If anything, this reminds of some JavaScript OOP implementations.)

• Use a framework. If you're comfortable with MVC, why don't you use one of MVC frameworks for Go that already exist? Beego and Revel come to mind.

• Rethink your architecture altogether. From what I see now, you are trying to write Go like it's Ruby-on-Rails. Go is different. Start with vanilla net/http and create a minimal implementation of your app. That's your prototype. With that prototype on your hands, you can rewrite it and expand it. Want resourceful routes? Add gorilla/mux or another router of choice. Need a data storage? Add an ORM. Want more testability and flexibility? Interfaces, interfaces everywhere.

If you use this:

var controllerProvider = map[string]interface{} {
   "user": &controllers.UserController{},
   "warehouse": &controllers.WarehouseController{},
 }

Be careful, these are not new instances for each access. If you use controllerProvider several times, it will always return the pointer to the instances initialized only once there.

You might want to use functions to dynamically generate instances:

var controllerProvider = map[string]func() interface{}{
	"user":      func() interface{} { return &controllers.UserController{} },
	"warehouse": func() interface{} { return &controllers.WarehouseController{} },
}

c := controllerProvider[appController]()