Go Model subclassing for Controller with structs

Question

Hi I'm trying to build a base framework for an REST API I'm building. I like to have one BaseController with regular CRUD actions. And I'd like to define a Model for each Controller. I think I'm pretty far with my approach, the only thing that still doesn't seem to work is the initialization of each component. I'm receiving this errors:

too few values in struct initializer

And:

cannot use Model literal (type Model) as type User in array element

My approach:

type Model struct {
    Id *bson.ObjectId
}

type Controller struct {
    model *Model
    arrayOfModels *[]Model
}

And then for example:

type User struct {
    Model
    someField string
}

type UserController struct {
    Controller
}

func NewUserController() UserController {
    return UserController{Controller{
         model: &User{Model{Id: nil}},
         arrayOfModels: &[]User{Model{Id: nil}},
    }}
}

I'm using this API together with Mgo (MongoDB adapter), and therefore I use bson.ObjectId

I'd like to know what I'm doing wrong and if I should use this approach and what could be better.

Help is greatly appreciated.

Sjors

Answer 1

I'd like to know what I'm doing wrong

A User is not a Model for embedding a Model . You can't use a value of type User where a Model is needed.

Polymorphism in Go is done through interfaces, not embedding.

Also, you're trying to do inheritance; Go does not support inheritance -- forget inheritance. That also means forget MVC as you know it.

Also, you're using pointers to everything. Don't; a pointer is costly because if it escapes a simple block scope the pointed-to value will be allocated on the heap instead of the stack. It's also harder to reason about pointers in more complicated situations.

You need a paradigm-shift, don't try to apply your "OO"-expertise to Go. Instead read the documentation, read other code and learn how to think in Go.