Building a RESTful API – CRUD Operations

A Minimal CRUD API

This lesson explains the main concept clearly with beginner-friendly examples and background so you can learn why the code works.

We will build a tiny in‑memory Todo API.

type Todo struct {
    ID   int    `json:"id"`
    Task string `json:"task"`
    Done bool   `json:"done"`
}

var (
    store   = map[int]Todo{}
    nextID  = 1
    storeMu sync.RWMutex
)

// Create
func createTodo(w http.ResponseWriter, r *http.Request) {
    var t Todo
    json.NewDecoder(r.Body).Decode(&t)
    storeMu.Lock()
    t.ID = nextID
    nextID++
    store[t.ID] = t
    storeMu.Unlock()
    w.WriteHeader(http.StatusCreated)
    json.NewEncoder(w).Encode(t)
}

// Read (list)
func listTodos(w http.ResponseWriter, r *http.Request) {
    storeMu.RLock()
    defer storeMu.RUnlock()
    var list []Todo
    for _, v := range store { list = append(list, v) }
    json.NewEncoder(w).Encode(list)
}

Register handlers with a router (http.ServeMux or chi).