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golang中mysql数据库出错【sql: 数据库已关闭】

来源：stackoverflow
2024-04-29 09:21:39
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问题内容

我尝试在golang中设置mysql数据库。

我创建了 db.go 用于 mysql 设置并将其导入到 main.go。

但是当我运行main.go时，由于db.go而发生错误。

我想解决这个错误。

没有编译错误。

但是当运行go run main.go时，出现错误。

main.go

package main

// import

func main() {
    err := godotenv.load()
    if err != nil {
    }
    db := db.newdatabase(os.getenv("mysql_user"), os.getenv("mysql_password"), os.getenv("mysql_host"))
    s3 := s3.news3(os.getenv("aws_access_key_id"), os.getenv("aws_secret_access_key"))
    dao := dao.newdao(db.database, s3)
    service := service.newservice(dao)
    cntlr := controller.newcontroller(service)

    router := gin.default()

    router.use(cors.new(cors.config{
        alloworigins:     []string{"*"},
        allowmethods:     []string{"get", "post", "options"},
        allowheaders:     []string{"content-type", "content-length", "accept-encoding", "x-csrf-token", "authorization", "accept", "origin", "cache-control", "x-requested-with"},
        exposeheaders:    []string{"content-length"},
        allowcredentials: true,
        alloworiginfunc: func(origin string) bool {
            return true
        },
        maxage: 15 * time.second,
    }))

    api := router.group("/api")
    {
        api.get("/articles", func(c *gin.context) {
            cntlr.getarticlecontroller(c)
        })
        api.get("/article/:id", func(c *gin.context) {
            cntlr.getsinglearticlecontroller(c)
        })
        api.get("/delete/:id", func(c *gin.context) {
            cntlr.deletearticlecontroller(c)
        })
        api.post("/post", func(c *gin.context) {
            cntlr.postcontroller(c)
        })
        api.post("/post/image", func(c *gin.context) {
            cntlr.postimagecontroller(c)
        })
        api.post("/post/image/db", func(c *gin.context) {
            cntlr.postimagetodbcontroller(c)
        })
    }

    router.run(":2345")
}

db.go

package db

import "database/sql"

type database struct {
    mysql_user     string
    mysql_password string
    mysql_host     string
    database       *sql.db
}

func newdatabase(user, password, host string) *database {
    db, err := sql.open("mysql", user+":"+password+"@tcp("+host+":3306)/article")
    if err != nil {
        panic(err.error())
    }

    defer db.close()

    err = db.ping()
    if err != nil {
        panic(err.error())
    }

    _, err = db.exec("create database if not exists article;")
    if err != nil {
        panic(err)
    }

    _, err = db.exec("use article;")
    if err != nil {
        panic(err)
    }

    _, err = db.exec("create table if not exists `articles` (`id` int not null auto_increment primary key,uuid varchar(36), `title` varchar(100) not null,`content` text not null ) engine=innodb default charset=utf8;")
    if err != nil {
        panic(err)
    }

    _, err = db.exec("create table if not exists images (id int auto_increment not null primary key, article_uuid varchar(36), image_name varchar(50)); ")
    if err != nil {
        panic(err)
    }
    database := new(database)
    database.database = db
    return database
}

这里是完整的源代码（分支：refactor-db）：

https://github.com/jpskgc/article/tree/refactor-db

我希望运行 go run main.go 时不会出现错误。

但实际情况并非如此。

db.go 周围会出现一些问题。

这是错误消息。

GET /api/articles HTTP/1.1
Host: localhost:2345
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3
Accept-Encoding: gzip, deflate, br
Accept-Language: en-US,en;q=0.9
Cache-Control: max-age=0
Connection: keep-alive
Sec-Fetch-Mode: navigate
Sec-Fetch-Site: none
Sec-Fetch-User: ?1
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.132 Safari/537.36


sql: database is closed
/Users/jpskgc/article/api/dao/dao.go:36 (0x1553240)
        (*Dao).GetArticleDao: panic(err.Error())
/Users/jpskgc/article/api/service/service.go:34 (0x17a9abb)
        Service.GetArticleService: results := s.dao.GetArticleDao()
/Users/jpskgc/article/api/controller/controller.go:19 (0x17cd664)
        Controller.GetArticleController: articles := controller.service.GetArticleService()
/Users/jpskgc/article/api/main.go:79 (0x17cec1f)
        main.func2: cntlr.GetArticleController(c)
/Users/jpskgc/go/pkg/mod/github.com/gin-gonic/[email protected]/context.go:124 (0x1791e89)
        (*Context).Next: c.handlers[c.index](c)
/Users/jpskgc/go/pkg/mod/github.com/gin-gonic/[email protected]/recovery.go:83 (0x17a5159)
        RecoveryWithWriter.func1: c.Next()
/Users/jpskgc/go/pkg/mod/github.com/gin-gonic/[email protected]/context.go:124 (0x1791e89)
        (*Context).Next: c.handlers[c.index](c)
/Users/jpskgc/go/pkg/mod/github.com/gin-gonic/[email protected]/logger.go:240 (0x17a4200)
        LoggerWithConfig.func1: c.Next()
/Users/jpskgc/go/pkg/mod/github.com/gin-gonic/[email protected]/context.go:124 (0x1791e89)
        (*Context).Next: c.handlers[c.index](c)
/Users/jpskgc/go/pkg/mod/github.com/gin-gonic/[email protected]/gin.go:389 (0x179b6a1)
        (*Engine).handleHTTPRequest: c.Next()
/Users/jpskgc/go/pkg/mod/github.com/gin-gonic/[email protected]/gin.go:351 (0x179aed3)
        (*Engine).ServeHTTP: engine.handleHTTPRequest(c)
/usr/local/go/src/net/http/server.go:2774 (0x12e2a07)
        serverHandler.ServeHTTP: handler.ServeHTTP(rw, req)
/usr/local/go/src/net/http/server.go:1878 (0x12de5f0)
        (*conn).serve: serverHandler{c.server}.ServeHTTP(w, w.req)
/usr/local/go/src/runtime/asm_amd64.s:1337 (0x1059ea0)
        goexit: BYTE    $0x90   // NOP

[GIN] 2019/09/10 - 16:58:46 | 500 |    5.990926ms |             ::1 | GET      /api/articles

解决方案

只需删除 db.go 中的 defer db.Close() 您需要关闭 NewDatabase 方法的连接

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