How in Golang use struct in other package file?

Question

I am new in Golang and need some help.

As you can see in the code below I am tring to create REST API in Golang. I use mux (Gorilla Mux) and pq (PostgreSQL driver) as third party libraries. Don't want to use ORM.

Inside application.go file I have InitializeRoutes function with a list of all aviable routes. GetFactors function process one of these routes. I am tring to define GetFactors function logic in other file called factors.go . Inside factors.go file I want to use Application struct which was defined in application.go . How to make it correctly? Right now as you can see they are in different packages. For thats why factors.go file don't see Application struct.

Project structure :

main.go
application.go
controllers
    factors.go

main.go:

package main

func main()  {
    application := Application{}
    application.Initialization()
    application.Run("localhost:8000")
}

application.go :

package main

import (
    "database/sql"
    "github.com/gorilla/mux"
    "log"
    "net/http"
    "rest-api/configurations"
)

type Application struct {
    Router *mux.Router
    Database *sql.DB
}

func (application *Application) Initialization() {
    var err error
    application.Database, err = configurations.DatabaseConnection()
    if err != nil {
        log.Fatal(err)
    }

    application.Router = mux.NewRouter()
    application.Router.StrictSlash(true)

    application.InitializeRoutes()
}

func (application *Application) Run(address string) {
    log.Fatal(http.ListenAndServe(address, application.Router))
}

func (application *Application) InitializeRoutes() {
    application.Router.HandleFunc("/api/factors", application.GetFactors).Methods("GET")
    // other code
}

controllers/factors.go :

package controllers

import (
    "net/http"
)

func (application *Application) GetFactors(rw http.ResponseWriter, request *http.Request) {
    // code
}

Answer 1

Well, finally I decided to redesign the project structure.

main.go
routes
    routes.go
controllers
    factors.go
models
    factors.go

main.go :

import (
    "your_project_name/routes"
)

func main()  {
    // code
    router := mux.NewRouter()
    routes.Use(router)
    // code
}

routes/routes.go :

package routes

import (
    "github.com/gorilla/mux"
    "your_application_name/controllers"
)

func Use(router *mux.Router) {
    router.HandleFunc("/api/factors", controllers.GetFactors).Methods("GET")
}

controllers/factors.go :

package controllers

var GetFactors = func(res http.ResponseWriter, req *http.Request) {
    // code
}