10 KiB
10 KiB
Todo — reference implementation (Go + Chi + SQLite)
This is a complete example. Generate equivalent structure for the given project. Use ONLY the fields from the JSON spec — do not add extras.
go.mod
Chi v5 router, modernc.org/sqlite (pure Go, no CGO).
module todo-go
go 1.23.0
toolchain go1.23.12
require (
github.com/go-chi/chi/v5 v5.2.1
modernc.org/sqlite v1.37.1
)
require (
github.com/dustin/go-humanize v1.0.1 // indirect
github.com/google/uuid v1.6.0 // indirect
github.com/mattn/go-isatty v0.0.20 // indirect
github.com/ncruces/go-strftime v0.1.9 // indirect
github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
golang.org/x/exp v0.0.0-20250408133849-7e4ce0ab07d0 // indirect
golang.org/x/sys v0.33.0 // indirect
modernc.org/libc v1.65.7 // indirect
modernc.org/mathutil v1.7.1 // indirect
modernc.org/memory v1.11.0 // indirect
)
models.go
Data structs: Todo (full row), CreateTodo (POST), UpdateTodo (PUT, all fields optional pointers).
package main
// Todo represents a task with priority and status tracking.
type Todo struct {
ID int64 `json:"id"`
Title string `json:"title"`
Description *string `json:"description,omitempty"`
DueDate *string `json:"due_date,omitempty"`
Priority int64 `json:"priority"`
Status string `json:"status"`
}
// CreateTodo is the request body for creating a new todo.
type CreateTodo struct {
Title string `json:"title"`
Description *string `json:"description,omitempty"`
DueDate *string `json:"due_date,omitempty"`
Priority *int64 `json:"priority,omitempty"`
Status *string `json:"status,omitempty"`
}
// UpdateTodo is the request body for updating an existing todo.
type UpdateTodo struct {
Title *string `json:"title,omitempty"`
Description *string `json:"description,omitempty"`
DueDate *string `json:"due_date,omitempty"`
Priority *int64 `json:"priority,omitempty"`
Status *string `json:"status,omitempty"`
}
handlers.go
CRUD handlers as closures taking *sql.DB. Key patterns: INSERT RETURNING, sql.ErrNoRows for 404, RowsAffected for delete.
package main
import (
"database/sql"
"encoding/json"
"net/http"
"strconv"
"github.com/go-chi/chi/v5"
)
// POST — decode JSON, defaults with nil-check, INSERT RETURNING, StatusCreated.
func createTodo(db *sql.DB) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
var input CreateTodo
if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
http.Error(w, err.Error(), http.StatusBadRequest); return
}
priority := int64(1)
if input.Priority != nil { priority = *input.Priority }
status := "pending"
if input.Status != nil { status = *input.Status }
var todo Todo
err := db.QueryRow(
`INSERT INTO todos (title, description, due_date, priority, status)
VALUES (?, ?, ?, ?, ?) RETURNING id, title, description, due_date, priority, status`,
input.Title, input.Description, input.DueDate, priority, status,
).Scan(&todo.ID, &todo.Title, &todo.Description, &todo.DueDate, &todo.Priority, &todo.Status)
if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError); return }
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(http.StatusCreated)
json.NewEncoder(w).Encode(todo)
}
}
// GET list — db.Query + rows.Scan loop, empty slice not nil.
func listTodos(db *sql.DB) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
rows, err := db.Query("SELECT id, title, description, due_date, priority, status FROM todos")
if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError); return }
defer rows.Close()
todos := []Todo{}
for rows.Next() {
var t Todo
rows.Scan(&t.ID, &t.Title, &t.Description, &t.DueDate, &t.Priority, &t.Status)
todos = append(todos, t)
}
w.Header().Set("Content-Type", "application/json")
json.NewEncoder(w).Encode(todos)
}
}
// GET by id — QueryRow + sql.ErrNoRows → 404.
func getTodo(db *sql.DB) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
id, _ := strconv.ParseInt(chi.URLParam(r, "id"), 10, 64)
var todo Todo
err := db.QueryRow(
"SELECT id, title, description, due_date, priority, status FROM todos WHERE id = ?", id,
).Scan(&todo.ID, &todo.Title, &todo.Description, &todo.DueDate, &todo.Priority, &todo.Status)
if err == sql.ErrNoRows { http.Error(w, "not found", http.StatusNotFound); return }
if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError); return }
w.Header().Set("Content-Type", "application/json")
json.NewEncoder(w).Encode(todo)
}
}
// PUT — fetch existing, merge with input nil-checks, UPDATE RETURNING.
func updateTodo(db *sql.DB) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
id, _ := strconv.ParseInt(chi.URLParam(r, "id"), 10, 64)
var existing Todo
err := db.QueryRow("SELECT id, title, description, due_date, priority, status FROM todos WHERE id = ?", id,
).Scan(&existing.ID, &existing.Title, &existing.Description, &existing.DueDate, &existing.Priority, &existing.Status)
if err == sql.ErrNoRows { http.Error(w, "not found", http.StatusNotFound); return }
if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError); return }
var input UpdateTodo
if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
http.Error(w, err.Error(), http.StatusBadRequest); return
}
if input.Title != nil { existing.Title = *input.Title }
if input.Description != nil { existing.Description = input.Description }
if input.DueDate != nil { existing.DueDate = input.DueDate }
if input.Priority != nil { existing.Priority = *input.Priority }
if input.Status != nil { existing.Status = *input.Status }
var updated Todo
err = db.QueryRow(
`UPDATE todos SET title=?, description=?, due_date=?, priority=?, status=? WHERE id=?
RETURNING id, title, description, due_date, priority, status`,
existing.Title, existing.Description, existing.DueDate, existing.Priority, existing.Status, id,
).Scan(&updated.ID, &updated.Title, &updated.Description, &updated.DueDate, &updated.Priority, &updated.Status)
if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError); return }
w.Header().Set("Content-Type", "application/json")
json.NewEncoder(w).Encode(updated)
}
}
// DELETE — Exec + RowsAffected == 0 → 404, else 204.
func deleteTodo(db *sql.DB) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
id, _ := strconv.ParseInt(chi.URLParam(r, "id"), 10, 64)
result, err := db.Exec("DELETE FROM todos WHERE id = ?", id)
if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError); return }
rows, _ := result.RowsAffected()
if rows == 0 { http.Error(w, "not found", http.StatusNotFound); return }
w.WriteHeader(http.StatusNoContent)
}
}
main.go
Entry point: SQLite connection, table init, Chi router on port 3000.
package main
import (
"database/sql"
"fmt"
"log"
"net/http"
"github.com/go-chi/chi/v5"
_ "modernc.org/sqlite"
)
// InitDB creates tables if they don't exist.
func InitDB(db *sql.DB) {
_, err := db.Exec(`CREATE TABLE IF NOT EXISTS todos (
id INTEGER PRIMARY KEY AUTOINCREMENT,
title TEXT NOT NULL,
description TEXT,
due_date TEXT,
priority INTEGER NOT NULL DEFAULT 1,
status TEXT NOT NULL DEFAULT 'pending'
)`)
if err != nil {
log.Fatal(err)
}
}
// NewRouter creates a chi router with all routes.
func NewRouter(db *sql.DB) http.Handler {
r := chi.NewRouter()
r.Post("/todos", createTodo(db))
r.Get("/todos", listTodos(db))
r.Get("/todos/{id}", getTodo(db))
r.Put("/todos/{id}", updateTodo(db))
r.Delete("/todos/{id}", deleteTodo(db))
return r
}
func main() {
db, err := sql.Open("sqlite", "file:app.db?mode=rwc")
if err != nil {
log.Fatal(err)
}
defer db.Close()
InitDB(db)
fmt.Println("Server running: http://127.0.0.1:3000")
log.Fatal(http.ListenAndServe("127.0.0.1:3000", NewRouter(db)))
}
handlers_test.go
Integration tests: setupTestServer with httptest.NewServer + :memory: SQLite, unique data per test.
package main
import (
"database/sql"
"encoding/json"
"fmt"
"net/http"
"net/http/httptest"
"strings"
"testing"
_ "modernc.org/sqlite"
)
func setupTestServer(t *testing.T) (*httptest.Server, *sql.DB) {
t.Helper()
db, err := sql.Open("sqlite", ":memory:")
if err != nil { t.Fatal(err) }
InitDB(db)
return httptest.NewServer(NewRouter(db)), db
}
func TestCreateTodo(t *testing.T) {
ts, db := setupTestServer(t)
defer ts.Close()
defer db.Close()
resp, err := http.Post(ts.URL+"/todos", "application/json",
strings.NewReader(`{"title":"Buy groceries","priority":2}`))
if err != nil { t.Fatal(err) }
defer resp.Body.Close()
if resp.StatusCode != http.StatusCreated { t.Fatalf("expected 201, got %d", resp.StatusCode) }
var body map[string]interface{}
json.NewDecoder(resp.Body).Decode(&body)
if body["title"] != "Buy groceries" { t.Fatalf("expected 'Buy groceries', got %v", body["title"]) }
if body["id"] == nil { t.Fatal("expected id") }
}
func TestGetTodoByID(t *testing.T) {
ts, db := setupTestServer(t)
defer ts.Close()
defer db.Close()
resp, _ := http.Post(ts.URL+"/todos", "application/json",
strings.NewReader(`{"title":"Fetchable task"}`))
var created map[string]interface{}
json.NewDecoder(resp.Body).Decode(&created)
resp.Body.Close()
id := created["id"].(float64)
resp, _ = http.Get(ts.URL + "/todos/" + fmt.Sprintf("%.0f", id))
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK { t.Fatalf("expected 200, got %d", resp.StatusCode) }
}
func TestGetTodoNotFound(t *testing.T) {
ts, db := setupTestServer(t)
defer ts.Close()
defer db.Close()
resp, _ := http.Get(ts.URL + "/todos/99999")
defer resp.Body.Close()
if resp.StatusCode != http.StatusNotFound { t.Fatalf("expected 404, got %d", resp.StatusCode) }
}
func TestDeleteTodo(t *testing.T) {
ts, db := setupTestServer(t)
defer ts.Close()
defer db.Close()
resp, _ := http.Post(ts.URL+"/todos", "application/json",
strings.NewReader(`{"title":"Deletable task"}`))
var created map[string]interface{}
json.NewDecoder(resp.Body).Decode(&created)
resp.Body.Close()
id := created["id"].(float64)
req, _ := http.NewRequest(http.MethodDelete, ts.URL+"/todos/"+fmt.Sprintf("%.0f", id), nil)
resp, _ = http.DefaultClient.Do(req)
defer resp.Body.Close()
if resp.StatusCode != http.StatusNoContent { t.Fatalf("expected 204, got %d", resp.StatusCode) }
resp, _ = http.Get(ts.URL + "/todos/" + fmt.Sprintf("%.0f", id))
defer resp.Body.Close()
if resp.StatusCode != http.StatusNotFound { t.Fatalf("expected 404 after delete, got %d", resp.StatusCode) }
}