《使用Gin框架构建分布式应用》阅读笔记：p77-p87

news/2024/10/19 8:51:04

《用Gin框架构建分布式应用》学习第5天，p77-p87总结，总计11页。

一、技术总结

1.Go知识点

(1)context

2.on-premises software

p80, A container is like a separate OS, but not virtualized; it only contains the dependencies needed for that one application, which makes the container portable and deployable on-premises or on the cloud。

premises的意思是“the land and buildings owned by someone, especially by a company or organization(归属于某人(尤指公司、组织)的土地或建筑物)”。简单来说 on-premises software 指的是运行在本地的服务(软件)。

wiki 对这个名称的定义很好，这里直接引用“On-premises software (abbreviated to on-prem, and often written as "on-premise") is installed and runs on computers on the premises of the person or organization using the software, rather than at a remote facility such as a server farm or cloud”。

3.openssl rand命令

openssl rand -base64 12 | docker secret create mongodb_password
-

rand 命令语法：

openssl rand [-help] [-out file] [-base64] [-hex] [-engine id] [-rand files] [-writerand file] [-provider name] [-provider-path path] [-propquery propq] num[K|M|G|T]

12对应 num参数。rand详细用法参考https://docs.openssl.org/3.4/man1/openssl-rand/。对于一个命令，我们需要掌握其有哪些参数及每个参数的含义。

4.查看docker latest tag对应的版本号

(1)未下载镜像

打开latest tag对应的页面，如：https://hub.docker.com/layers/library/mongo/latest/images/sha256-e6e25844ac0e7bc174ab712bdd11bfca4128bf64d28f85d0c6835c979e4a5ff9，搜索 VERSION，然后找到版本号。

(2)已下载镜像

使用 docker inspect 命令进行查看。

# docker inspect d32 | grep -i version"DockerVersion": "","GOSU_VERSION=1.17","JSYAML_VERSION=3.13.1","MONGO_VERSION=8.0.1","org.opencontainers.image.version": "24.04"

5.mongo-go-driver示例

书上代码使用的mongo-go-driver v1.4.5，现在已经更新到了v2.0.0，导致有些代码无法运行，建议使用最新版。这里还得再吐槽下 Go 生态圈的文档写得太糟糕了。示例：

client, _ := mongo.Connect(options.Client().ApplyURI("mongodb://localhost:27017"))
ctx, cancel = context.WithTimeout(context.Background(), 2*time.Second)
defer cancel()_ = client.Ping(ctx, readpref.Primary())

个人认为，上面的代码 err 就不应该忽略掉。而应该是：

package mainimport ("context""github.com/gin-gonic/gin""github.com/rs/xid""go.mongodb.org/mongo-driver/v2/mongo""go.mongodb.org/mongo-driver/v2/mongo/options""go.mongodb.org/mongo-driver/v2/mongo/readpref""log""net/http""strings""time"
)type Recipe struct {ID           string    `json:"id"`Name         string    `json:"name"`Tags         []string  `json:"tags"`Ingredients  []string  `json:"ingredients"`Instructions []string  `json:"instructions"`PublishAt    time.Time `json:"publishAt"`
}var recipes []Recipefunc init() {// 方式1：使用内存进行初始化// recipes = make([]Recipe, 0)// file, err := os.Open("recipes.json")// if err != nil {// 	log.Fatal(err)// 	return// }// defer file.Close()//// // 反序列化：将json转为slice// decoder := json.NewDecoder(file)// err = decoder.Decode(&recipes)// if err != nil {// 	log.Fatal(err)// 	return// }// 方式2：使用 MongoDB 存储数据ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)defer cancel()// 创建连接,这里的 err 针对的是 URI 错误client, err := mongo.Connect(options.Client().ApplyURI("mongodb1://admin:admin@localhost:27017"))if err != nil {log.Fatal("MongoDB connect error: ", err)}// 判断连接是否成功if err := client.Ping(ctx, readpref.Primary()); err != nil {log.Fatal("MongoDB Ping error: ", err)}log.Println("Connected to MongoDB successfully.")}// swagger:route POST /recipes  createRecipe
//
// # Create a new recipe
//
// Responses:
//
//	200: recipeResponse
//
// NewRecipeHandler 新增recipe,是按照单个新增，所以这里名称这里用的是单数
func NewRecipeHandler(c *gin.Context) {var recipe Recipeif err := c.ShouldBindJSON(&recipe); err != nil {c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})return}recipe.ID = xid.New().String()recipe.PublishAt = time.Now()recipes = append(recipes, recipe)c.JSON(http.StatusOK, recipe)
}// swagger:route GET /recipes  listRecipes
// Returns list of recipes
// ---
// produces:
// - application/json
// responses:
// '200':
// description: Successful operation
// ListRecipesHandler 差下recipes，因为是查询所有，所以名称这里用的是复数
func ListRecipesHandler(c *gin.Context) {c.JSON(http.StatusOK, recipes)
}// UpdateRecipeHandler 更新 recipe，因为是单个，所以使用的是单数。
// id 从 path 获取，其它参数从 body 获取。
func UpdateRecipeHandler(c *gin.Context) {id := c.Param("id")// 数据解码var recipe Recipeif err := c.ShouldBindJSON(&recipe); err != nil {c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})return}// 判断 id 是否存在index := -1for i := 0; i < len(recipes); i++ {if recipes[i].ID == id {index = i}}// 如果 id 不存在if index == -1 {c.JSON(http.StatusNotFound, gin.H{"error": "recipe not found"})return}// 如果 id 存在则进行更新recipes[index] = recipec.JSON(http.StatusOK, recipe)
}// DeleteRecipeHandler 删除 recipe: 1.删除之前判断是否存在，存在就删除，不存在就提示不存在。
func DeleteRecipeHandler(c *gin.Context) {id := c.Param("id")index := -1for i := 0; i < len(recipes); i++ {if recipes[i].ID == id {index = i}}if index == -1 {c.JSON(http.StatusNotFound, gin.H{"message": "recipe not found"})return}recipes = append(recipes[:index], recipes[index+1:]...)c.JSON(http.StatusOK, gin.H{"message": "recipe deleted",})
}// SearchRecipesHandler 查询 recipes
func SearchRecipesHandler(c *gin.Context) {tag := c.Query("tag")listOfRecipes := make([]Recipe, 0)for i := 0; i < len(recipes); i++ {found := falsefor _, t := range recipes[i].Tags {if strings.EqualFold(t, tag) {found = true}if found {listOfRecipes = append(listOfRecipes, recipes[i])}}}c.JSON(http.StatusOK, listOfRecipes)
}
func main() {router := gin.Default()router.POST("/recipes", NewRecipeHandler)router.GET("/recipes", ListRecipesHandler)router.PUT("/recipes/:id", UpdateRecipeHandler)router.DELETE("/recipes/:id", DeleteRecipeHandler)router.GET("/recipes/search", SearchRecipesHandler)err := router.Run()if err != nil {return}
}