golang - gin demo解析

Posted on   |   In

gin 初探

原文地址: https://ryanmccue.ca/creating-an-api-with-golang-gin-framework/

解析

总体结构

代码分解

  • main.go
package main

import (
	"log"

	"github.com/gin-gonic/gin"
	"vincent.com/gin/todo/controllers"
	"vincent.com/gin/todo/routes"
	"vincent.com/gin/todo/utils/database"
)

func main() {
	// 链接db 获取实例
	db, err := database.Connect("postgres", "", "postgres", "192.168.33.10", "5432")
	if err != nil {
		log.Fatal("err", err)
	}
	// binding db 和 controller
	todoController := controllers.NewTodoController(db)
	// 默认配置
	r := gin.Default()
	// 路由注册
	routes.CreateRoutes(r, todoController)
	// 默认8080端口
	r.Run()
}
  • database.go
    数据链接函数
package database

import (
	"database/sql"
	"fmt"
	// import pg
	_ "github.com/lib/pq"
)

// Connect function for pgsql
func Connect(user, password, dbname, host, port string) (*sql.DB, error) {
	connStr := fmt.Sprintf("user=%s password=%s dbname=%s host=%s port=%s sslmode=disable",
		user, password, dbname, host, port)
	return sql.Open("postgres", connStr)
}
  • items.go 数据模型
package models

// Item - todo item model
type Item struct {
	ID          int    `json:"id"`
	Title       string `json:"title"`
	Description string `json:"description"`
	Completed   bool   `json:"status"`
}
  • todo_controller.go 参数/error/调用 actions
package controllers

import (
	"database/sql"
	"log"
	"net/http"
	"strconv"

	"github.com/gin-gonic/gin"
	"vincent.com/gin/todo/repositories"
)

//NewTodoController - create todo controller with mehtod dealing with todo item
func NewTodoController(db *sql.DB) *TodoController {
	return &TodoController{DB: db}
}

//TodoController struct
type TodoController struct {
	DB *sql.DB
}

//Create - get req and create one todo item into pg
func (tc *TodoController) Create(c *gin.Context) {
	// 解析参数
	title := c.PostForm("title")
	description := c.PostForm("description")
	// 调用 sql层
	_, err := repositories.CreateItem(tc.DB, title, description)
	// 错误处理
	if err != nil {
		log.Println("err", err)
		c.String(http.StatusInternalServerError, "")
		return
	}
	c.String(http.StatusCreated, "")
}

//Items - query todo items from pg
func (tc *TodoController) Items(c *gin.Context) {
	allStr := c.Query("all")
	all, err := strconv.ParseBool(allStr)
	if err != nil {
		all = true
	}
	items, err := repositories.GetItems(tc.DB, all)
	if err != nil {
		log.Println("err", err)
		c.String(http.StatusInternalServerError, "")
		return
	}
	c.JSON(http.StatusOK, items)
}

//Get - get one item with id
func (tc *TodoController) Get(c *gin.Context) {
	itemIDStr := c.Params.ByName("itemID")
	itemID, err := strconv.Atoi(itemIDStr)
	if err != nil {
		c.JSON(http.StatusBadRequest, map[string]string{
			"error": "Bad item id",
		})
		return
	}
	item, err := repositories.GetItem(tc.DB, itemID)
	if err != nil {
		if err == sql.ErrNoRows {
			c.String(http.StatusNotFound, "")
			return
		}
		log.Println("err", err)
		c.String(http.StatusInternalServerError, "")
		return
	}
	c.JSON(http.StatusOK, item)
}

//Update - update item with id
func (tc *TodoController) Update(c *gin.Context) {
	itemIDStr := c.Params.ByName("itemID")
	itemID, err := strconv.Atoi(itemIDStr)
	if err != nil {
		log.Println("err", err)
		c.JSON(http.StatusBadRequest, map[string]string{
			"error": "Bad item id",
		})
		return
	}
	title := c.PostForm("title")
	description := c.PostForm("description")
	completedStr := c.PostForm("completed")
	completed, err := strconv.ParseBool(completedStr)
	if err != nil {
		c.JSON(http.StatusBadRequest, map[string]string{
			"error": "Bad completed input",
		})
		return
	}
	err = repositories.UpdateItem(tc.DB, itemID, title, description, completed)
	if err != nil {
		log.Println("err", err)
		c.String(http.StatusInternalServerError, "")
		return
	}
	c.String(http.StatusOK, "")
}

//Delete - del item with id
func (tc *TodoController) Delete(c *gin.Context) {
	itemIDStr := c.Param("itemID")
	itemID, err := strconv.Atoi(itemIDStr)
	if err != nil {
		c.JSON(http.StatusBadRequest, map[string]string{
			"error": "Bad item id",
		})
		return
	}
	err = repositories.DeleteItem(tc.DB, itemID)
	if err != nil {
		log.Println("err", err)
		c.String(http.StatusInternalServerError, "")
		return
	}
	c.String(http.StatusOK, "")
}
  • routes.go 关联  路由和 controller

    此  例子没有分组

package routes

import (
	"github.com/gin-gonic/gin"
	"vincent.com/gin/todo/controllers"
)

//CreateRoutes - bind controller with gin
func CreateRoutes(r *gin.Engine, tc *controllers.TodoController) {
	r.GET("/items", tc.Items)
	r.POST("/item", tc.Create)
	r.GET("/item/:itemID", tc.Get)
	r.PUT("/item/:itemID", tc.Update)
	r.DELETE("/item/:itemID", tc.Delete)
}
  • todo_repository.go 操作 db
package repositories

import (
	"database/sql"

	"vincent.com/gin/todo/models"
)

//GetItems - get items from pg
func GetItems(db *sql.DB, all bool) ([]*models.Item, error) {
	var rows *sql.Rows
	var err error
	query := `
		select
			id,
			title,
			description,
			completed
		from
			items
	`
	if !all {
		query += "where completed = $1"
		rows, err = db.Query(query, all)
	} else {
		rows, err = db.Query(query)
	}

	if err != nil {
		return nil, err
	}
	items := make([]*models.Item, 0)

	for rows.Next() {
		var item models.Item
		err = rows.Scan(&item.ID, &item.Title, &item.Description, &item.Completed)
		if err != nil {
			return nil, err
		}
		items = append(items, &item)
	}
	return items, err
}

//CreateItem - add new todo item
func CreateItem(db *sql.DB, title, description string) (int, error) {
	const query = `
		insert into items (
			title,
			description
		) values (
			$1,
			$2
		) returning id
	`
	var id int
	err := db.QueryRow(query, title, description).Scan(&id)
	return id, err
}

//UpdateItem - update item base on id
func UpdateItem(db *sql.DB, id int, title, description string, completed bool) error {
	const query = `
		update items set
			title = $1,
			description = $2,
			completed = $3
		where id = $4
	`
	_, err := db.Exec(query, title, description, completed, id)
	return err
}

//GetItem - get item with specific id
func GetItem(db *sql.DB, id int) (*models.Item, error) {
	const query = `
		select
			id,
			title,
			description,
			completed
		from
			items
		where
			id = $1
	`
	var item models.Item
	err := db.QueryRow(query, id).Scan(&item.ID, &item.Title, &item.Description, &item.Completed)
	return &item, err
}

//DeleteItem - del the todo item with specific id
func DeleteItem(db *sql.DB, id int) error {
	const query = `delete from items where id = $1`
	_, err := db.Exec(query, id)
	return err
}