Cannot Access Unexported Field

Why This Happens

In Go, identifiers starting with a lowercase letter are unexported (private to the package). You cannot access them from outside the package. This applies to struct fields, methods, functions, and types. To make them accessible, capitalize the first letter.

The Problem

// package models
type User struct {
    name string // unexported
}

// package main
func main() {
    u := models.User{}
    u.name = "Alice" // cannot access unexported field
}

The Fix

// package models
type User struct {
    Name string // exported
}

// package main
func main() {
    u := models.User{}
    u.Name = "Alice" // works fine
}

Step-by-Step Fix

1. 1

   Identify the unexported identifier

   Check if the field or method starts with a lowercase letter.

2. 2

   Decide on the access pattern

   Determine if the field should be exported or if access should go through a getter method.

3. 3

   Export or add accessor

   Capitalize the first letter to export, or add a public method that returns the private field.