最近有项目要使用 Go 开发，作为一个. NET Core 选手，准备先撸一个包含 CRUD 的最小 MVP 项目练手。
要创建一个 TODO 应用，会创建下面这些接口：
| API | Description | Request body | Response body |
|---|---|---|---|
GET /todoitems | Get all to-do items | None | Array of to-do items |
GET /todoitems/complete | Get completed to-do items | None | Array of to-do items |
GET /todoitems/{id} | Get an item by ID | None | To-do item |
POST /todoitems | Add a new item | To-do item | To-do item |
PUT /todoitems/{id} | Update an existing item | To-do item | None |
DELETE /todoitems/{id} | Delete an item | None | None |
我觉得，做这样一个 API 应用，不管是 Go 还是其他语言，思路是一样的，无外乎：SDK 版本、开发工具、服务容器、HTTP 请求和响应处理、数据库对应的语言驱动、实体定义和映射、JSON 处理等等。因此，其他语言怎么做，换成 Go 之后，找对应的工具和实现方案就可以了。
1 、快速搭建开发环境
- 官方下载 SDK：Download and install - The Go Programming Language
- 安装 VS Code：Download Visual Studio Code - Mac, Linux, Windows
- 安装扩展：“Go”
- 安装 Go 工具包：
ctrl+shift+p，输入go install回车后，选择全部工具安装
2、构建 API
2 .1、创建目录，初始化项目
go mod init todo-list-api
安装依赖包：
- gorilla/mux 是一个强大的 HTTP 路由器和 URL 匹配器，用于构建 Go Web 服务器： gorilla/mux: Package gorilla/mux is a powerful HTTP router and URL matcher for building Go web servers with 🦍 (github.com)
go get -u github.com/gorilla/mux
- Postgres 数据库的 Go 驱动包：lib/pq: Pure Go Postgres driver for database/sql (github.com)
go get github.com/lib/pq
2.2、入口函数
新增 main.go 文件，内容如下：
func main() {r := mux.NewRouter()r.HandleFunc("/api/todoitems", GetToDoItems).Methods("GET")r.HandleFunc("/api/todoitems/complete", GetToDoItemInCompleted).Methods("GET")r.HandleFunc("/api/todoitems/{id}", GetToDoItemById).Methods("GET")r.HandleFunc("/api/todoitems", CreateToDoItem).Methods("POST")r.HandleFunc("/api/todoitems/{id}", DeleteToDoItem).Methods("DELETE")r.HandleFunc("/api/todoitems/{id}", UpdateToDoItem).Methods("PUT")srv := &http.Server{Handler: r,Addr: ":3000",WriteTimeout: 15 * time.Second,ReadTimeout: 15 * time.Second,}log.Fatal(srv.ListenAndServe())
}
HandleFunc 函数第一个参数是路由路径，第二个参数是处理函数，然后链式调用 Methods 指定可以处理的 HTTP 请求类型。
2.3、实体和数据库
新增 db.go 文件，内容如下：
var DB *sql.DB
func ConnectToDatabase() {connStr := "user=postgres dbname=postgres password=Mysoft7789 sslmode=disable"db, err := sql.Open("postgres", connStr)if err != nil {log.Fatal(err)}DB = db
}
这个函数用来打开并获取数据库连接，放在 init 方法中调用
func init() {ConnectToDatabase()
}
定义结构类型 ToDo，内容如下：
type Todo struct {Id int `json:"id"`Name string `json:"name"`IsComplete bool `json:"is_complete"`
}
创建 postgres 数据表
create table public.t_todo_item
( id integer generated by default as identity, name varchar(20), is_complete boolean
);
2 .4、实现 API
新增 todo-service.go 实现所有的 API
func GetToDoItems(w http.ResponseWriter, r *http.Request) {rows, err := DB.Query("select id,name,is_complete from t_todo_item")if err != nil {panic(err.Error())}var todos []Todofor rows.Next() {var todo Todoerr = rows.Scan(&todo.Id, &todo.Name, &todo.IsComplete)if err != nil {log.Printf("Error happened in scan row. Err: %s", err)w.WriteHeader(http.StatusInternalServerError)return}todos = append(todos, todo)}jsonResp, err := json.Marshal(todos)if err != nil {log.Fatalf("Error happened in JSON marshal. Err: %s", err)w.WriteHeader(http.StatusInternalServerError)return}w.Header().Set("Content-Type", "application/json")w.Write(jsonResp)
}func GetToDoItemInCompleted(w http.ResponseWriter, r *http.Request) {rows, err := DB.Query("select id,name,is_complete from t_todo_item where is_complete = true")if err != nil {panic(err.Error())}var todos []Todofor rows.Next() {var todo Todoerr = rows.Scan(&todo.Id, &todo.Name, &todo.IsComplete)if err != nil {log.Printf("Error happened in scan row. Err: %s", err)w.WriteHeader(http.StatusInternalServerError)return}todos = append(todos, todo)}jsonResp, err := json.Marshal(todos)if err != nil {log.Fatalf("Error happened in JSON marshal. Err: %s", err)w.WriteHeader(http.StatusInternalServerError)return}w.Header().Set("Content-Type", "application/json")w.Write(jsonResp)
}func CreateToDoItem(w http.ResponseWriter, r *http.Request) {// convert todo struct from bodyvar todo Todoerr := json.NewDecoder(r.Body).Decode(&todo)if err != nil {log.Printf("Error happened in JSON unmarshal. Err: %s", err)return}// insert into dberr = DB.QueryRow("insert into t_todo_item (name, is_complete) values ($1, $2) RETURNING id", todo.Name, false).Scan(&todo.Id)if err != nil {log.Printf("Error happened in insert into db. Err: %s", err)w.WriteHeader(http.StatusInternalServerError)return}// return created todojsonResp, _ := json.Marshal(todo)w.Header().Set("Content-Type", "application/json")w.Write(jsonResp)
}func GetToDoItemById(w http.ResponseWriter, r *http.Request) {vars := mux.Vars(r)id := vars["id"]row := DB.QueryRow("select id,name, is_complete from t_todo_item where id = $1", id)var todo Todorow.Scan(&todo.Id, &todo.Name, &todo.IsComplete)jsonResp, err := json.Marshal(todo)if err != nil {log.Fatalf("Error happened in JSON marshal. Err: %s", err)w.WriteHeader(http.StatusInternalServerError)return}w.Header().Set("Content-Type", "application/json")w.Write(jsonResp)
}func DeleteToDoItem(w http.ResponseWriter, r *http.Request) {// check id from urlvars := mux.Vars(r)// convert id to intid, err := strconv.Atoi(vars["id"])if err != nil {log.Printf("Error happened in convert id to int. Err: %s", err)w.WriteHeader(http.StatusBadRequest)return}// if id less then 0, return 400if condition := id < 0; condition {w.WriteHeader(http.StatusBadRequest)return}// delete from db_, err = DB.Exec("delete from t_todo_item where id = $1", id)if err != nil {log.Printf("Error happened in delete from db. Err: %s", err)w.WriteHeader(http.StatusInternalServerError)return}w.WriteHeader(http.StatusOK)
}func UpdateToDoItem(w http.ResponseWriter, r *http.Request) {// check id from urlvars := mux.Vars(r)// convert id to intid, err := strconv.Atoi(vars["id"])if err != nil {log.Printf("Error happened in convert id to int. Err: %s", err)w.WriteHeader(http.StatusBadRequest)return}// if id less then 0, return 400if condition := id < 0; condition {w.WriteHeader(http.StatusBadRequest)return}// convert todo struct from bodyvar todo Todoerr = json.NewDecoder(r.Body).Decode(&todo)if err != nil {log.Printf("Error happened in JSON unmarshal. Err: %s", err)}todo.Id = id// update db_, err = DB.Exec("update t_todo_item set name = $1, is_complete = $2 where id = $3", todo.Name, todo.IsComplete, id)if err != nil {log.Printf("Error happened in update db. Err: %s", err)w.WriteHeader(http.StatusInternalServerError)return}w.WriteHeader(http.StatusOK)
}
2.5、测试验证
新增一个 todo.http 文件，内容如下：
# GET request to retrieve all todo itemsGET http://localhost:3000/api/todoitems HTTP/1.1#### GET request to retrieve a specific todo item by idGET http://localhost:3000/api/todoitems/20 HTTP/1.1#### GET request to retrieve all completed todo itemsGET http://localhost:3000/api/todoitems/complete HTTP/1.1 #### POST request to create a new todo itemPOST http://localhost:3000/api/todoitems HTTP/1.1Content-Type: application/json {"name": "Buy grocerie1"
}#### PUT request to update an existing todo itemPUT http://localhost:3000/api/todoitems/20 HTTP/1.1Content-Type: application/json{"name": "Buy groceries","is_complete": true
}#### DELETE request to delete a todo itemDELETE http://localhost:3000/api/todoitems/2 HTTP/1.1
完工了。