如今微服务、无服务器架构大行其道。而API开发是这些话题的主角。
Go语言开发效率要比Java Spring要快一些，性能上比PHP高出一个数量级。尤其是Go语言在并发方便非常的优秀，是2017年值得关注的一门语言。
本文通过一个经典的Todo应用来介绍使用Go语言开发API。
配套的演示代码

主要涉及的内容：

• API开发框架gin-gonic
• ORM框架gorm
• Go语言mysql驱动

依赖包

$ go get gopkg.in/gin-gonic/gin.v1
$ go get -u github.com/jinzhu/gorm
$ go get github.com/go-sql-driver/mysql

接口文档：

一、Hello World

package main

import "github.com/gin-gonic/gin"

func main() {
    r := gin.Default()
    r.GET("/ping", func(c *gin.Context) {
        c.JSON(200, gin.H{
            "message": "pong",
        })
    })
    r.Run() // listen and serve on 0.0.0.0:8080
}

二、路由设计

package main

import "github.com/gin-gonic/gin"

var router = gin.Default()

func init()  {
    router := gin.Default()

    v1 := router.Group("/api/v1/todos")
    {
        v1.POST("/", createTodo)
        v1.GET("/", fetchAllTodo)
        v1.GET("/:id", fetchSingleTodo)
        v1.PUT("/:id", updateTodo)
        v1.DELETE("/:id", deleteTodo)
    }
}

三、设计数据库

drop database if exists demo;
create database demo charset='utf8';

use demo;

drop table if exists todo;
create table todo (

    primary key(id),
    id int not null auto_increment,
    title varchar(256) not null default '待办事项',
    completed bool not null default 0,

    created_at timestamp not null default current_timestamp,
    updated_at timestamp not null default current_timestamp,
    deleted_at timestamp not null default current_timestamp
) Engine=Innodb;

四、连接数据库

package main

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

var (
    db *gorm.DB
    sqlConnection = "golang:1234567890@(114.115.136.205)/demo?charset=utf8&parseTime=True&loc=Local"
)

func init() {
    //打开数据库连接
    var err error
    db, err = gorm.Open("mysql", sqlConnection)
    if err != nil {
        panic("failed to connect database")
    }

    db.AutoMigrate(&todoModel{})
}

五、模型设计

package main

import "github.com/jinzhu/gorm"

type (
    // entity类
    todoModel struct {
        gorm.Model
        Title     string `json:"title"`
        Completed int    `json:"completed"`
    }

    // response entity
    transformedTodo struct {
        ID        uint   `json:"id"`
        Title     string `json:"title"`
        Completed bool   `json:"completed"`
    }
)

六、CRUD

package main

import (
    "github.com/gin-gonic/gin"
    "strconv"
    "net/http"
)

// createTodo add a new todo
func createTodo(c *gin.Context) {
    completed, _ := strconv.Atoi(c.PostForm("completed"))
    todo := todoModel{Title: c.PostForm("title"), Completed: completed}
    db.Save(&todo)
    c.JSON(http.StatusCreated, gin.H{"status": http.StatusCreated, "message": "Todo item created successfully!", "resourceId": todo.ID})
}

// fetchAllTodo fetch all todos
func fetchAllTodo(c *gin.Context) {
    var todos []todoModel
    var _todos []transformedTodo

    db.Find(&todos)

    if len(todos) <= 0 {
        c.JSON(http.StatusNotFound, gin.H{"status": http.StatusNotFound, "message": "No todo found!"})
        return
    }

    //transforms the todos for building a good response
    for _, item := range todos {
        completed := false
        if item.Completed == 1 {
            completed = true
        } else {
            completed = false
        }
        _todos = append(_todos, transformedTodo{ID: item.ID, Title: item.Title, Completed: completed})
    }
    c.JSON(http.StatusOK, gin.H{"status": http.StatusOK, "data": _todos})
}

// fetchSingleTodo fetch a single todo
func fetchSingleTodo(c *gin.Context) {
    var todo todoModel
    todoID := c.Param("id")

    db.First(&todo, todoID)

    if todo.ID == 0 {
        c.JSON(http.StatusNotFound, gin.H{"status": http.StatusNotFound, "message": "No todo found!"})
        return
    }

    completed := false
    if todo.Completed == 1 {
        completed = true
    } else {
        completed = false
    }

    _todo := transformedTodo{ID: todo.ID, Title: todo.Title, Completed: completed}
    c.JSON(http.StatusOK, gin.H{"status": http.StatusOK, "data": _todo})
}

// updateTodo update a todo
func updateTodo(c *gin.Context) {
    var todo todoModel
    todoID := c.Param("id")

    db.First(&todo, todoID)

    if todo.ID == 0 {
        c.JSON(http.StatusNotFound, gin.H{"status": http.StatusNotFound, "message": "No todo found!"})
        return
    }

    db.Model(&todo).Update("title", c.PostForm("title"))
    completed, _ := strconv.Atoi(c.PostForm("completed"))
    db.Model(&todo).Update("completed", completed)
    c.JSON(http.StatusOK, gin.H{"status": http.StatusOK, "message": "Todo updated successfully!"})
}

// deleteTodo remove a todo
func deleteTodo(c *gin.Context) {
    var todo todoModel
    todoID := c.Param("id")

    db.First(&todo, todoID)

    if todo.ID == 0 {
        c.JSON(http.StatusNotFound, gin.H{"status": http.StatusNotFound, "message": "No todo found!"})
        return
    }

    db.Delete(&todo)
    c.JSON(http.StatusOK, gin.H{"status": http.StatusOK, "message": "Todo deleted successfully!"})
}

七、编译打包

将多个go文件打包为一个可执行文件

go build main.go router.go controller.go config.go model.go

如果把所有的代码放在一个文件里面，直接运行即可go build main.go。
为了方便展示，这里给出了已经打包好的文件

八、单元测试（略）

九、运维上线

nohup ./main &

十、效果展示

创建:

获取：

更新：

删除：

本文的原始项目是来自原文地址。
但是由于一些本土化的需要（不用翻墙），做了较大的改动。