I am new to golang and trying to make API server using gin + gorm.  

I tried to build the code below but I am getting `type *gorm.DB has no field or method GetUsers` error.  

This is a very simple API server and only I want to do is get all users from `users` table.

```
package models

import (
    "github.com/jinzhu/gorm"
    _ "github.com/jinzhu/gorm/dialects/postgres"
)

var db *gorm.DB

func init() {
    var err error
    db, err = gorm.Open("postgres", "host=localhost dbname=test user=postgres password=test sslmode=disable")
    if err != nil {
        return err
    }
}

type User struct {
   ID           int    `json:"id"`
   Username     string `json:"name"`
}

func NewUser(id int, name string) User {
    return User{
      ID:           id,
      Username:     name,
    }
}

// UserRepository
type UserRepository struct {
}

func NewUserRepository() UserRepository {
    return UserRepository{}
}

func (m UserRepository) GetUsers() []*User {
    var users []*User
    has, _ := db.GetUsers(&users)
    if has {
         return users
    }
    return nil
}

```

I implemented `GetUsers()` in `controllers/user.go`and I also created `users` table.  
I have no idea why it says `no field or method GetUsers`.Someone give me an advice to solve this.

```
package controllers

import (
     "api-server/models"
)

type User struct {
}

func NewUser() User {
     return User{}
}

func (c User) GetUsers() interface{} {
     repo := models.NewUserRepository()
     user := repo.GetUsers()
     return user
}

```