How to correctly use structures in files of the same package?

Question

go

Hello comrades! Please help me figure it out.
I'm trying to create a REST API in Golang. I use third party packages mux( Gorilla Mux ) and pq( PostgreSQL driver ) for this purpose. ORM is not going to use.
Faced the following problem. In the factors.go file, I am trying to use the Application structure , which was described in the application.go file . The files factors.go and application.go belong to the same package. How to call the GetFactors function in the application.go file? How to use the structure correctly in the factors.go fileapplication ? Perhaps a redesign is needed?
The project structure looks like this :

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"
  "rest-api/controllers"
)

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", controllers.GetFactors).Methods("GET")
  // Остальной код
}

factors.go :

package main

import (
  "net/http"
)

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

Answer 1

`factors.go` cannot be part of the `main` package, as it is in the `controllers` package.
And there is a suspicion that the code will not build anyway, since the `main` module in the `application.go` file depends on the `controllers` module of the `factors.go` file, while the `controllers` module in the `factors.go` file depends on the `main` module of `application.go`. It turns out recursion, and the code will not be able to assemble.