将数据从函数插入到mysql数据库。api接口

Question

高级:我的程序得到一个长URL，并使它更短(比如tinyurl)。但是我在将长URL变量和shortURL变量从函数传递到mySQL数据库时遇到了问题。我已经试着在网上查过了，但是我所得到的信息与我所拥有的不太接近。我只发布了我的部分代码，完整的代码将在游乐场中

var db *sql.DB            //global variable

func main(){
var db, err = sql.Open("mysql", dsn())
    if err != nil {
        fmt.Println(err.Error())
    } else {
        fmt.Printf("Connection established to MYSQL server\n%s\n", dsn())
    }
    defer db.Close()

    linkList = map[string]string{}

    http.HandleFunc("/link", addLink)
    http.HandleFunc("/hpe/", getLink)
    http.HandleFunc("/", Home)

    // Flags to pass string ip or port to WEB app
    ip := flag.String("i", "0.0.0.0", "")
    port := flag.String("p", "8080", "")
    flag.Parse()
    fmt.Printf("Web application listening on %s \n", net.JoinHostPort(*ip, *port))
    log.Fatal(http.ListenAndServe(net.JoinHostPort(*ip, *port), nil))
}

函数，该函数创建短url。每次调用此函数时，它都会生成链接。

func addLink(w http.ResponseWriter, r *http.Request) {
    log.Println("Add Link")
    key, ok := r.URL.Query()["ik"]
    if ok {
        if !validLink(key[0]) {
            w.WriteHeader(http.StatusBadRequest)
            fmt.Fprintf(w, "Could not create shortlink need absolute path link.")
            return
        }
        log.Println(key)
        if _, ok := linkList[key[0]]; !ok {
            genString := randomString(5)
            linkList[genString] = key[0]
            w.Header().Set("Content-Type", "text/html")
            w.WriteHeader(http.StatusAccepted)

        linkString := fmt.Sprintf("<a href=\"hpe/%s\">hpe/%s</a>", genString, genString)
            fmt.Fprintf(w, "Added shortlink\n")
            fmt.Fprintf(w, linkString)
            return
            // database function

            defer db.Close()
            s:
    result, err := db.Exec("insert into Url (LongUrl, ShortUrl) value(?,?);",genString,linkString)
            if err != nil {
                fmt.Print(err.Error())
            } else {
                _,err:=result.LastInsertId()
                
            }

            

        }
        w.WriteHeader(http.StatusConflict)
        fmt.Fprintf(w, "Already have this link")
        return
    }
    w.WriteHeader(http.StatusBadRequest)
    fmt.Fprintf(w, "Failed to add link")
    return
}

func getLink(w http.ResponseWriter, r *http.Request) {
    path := r.URL.Path
    log.Println("Get Link:", path)
    pathArgs := strings.Split(path, "/")
    if len(pathArgs[2]) < 1 {
        w.WriteHeader(http.StatusNotFound)
        http.Redirect(w, r, "0.0.0.0:8080", http.StatusTemporaryRedirect)
        return
    }
    log.Printf("Redirected to: %s", linkList[pathArgs[2]])
    http.Redirect(w, r, linkList[pathArgs[2]], http.StatusTemporaryRedirect)
    //fmt.Printf("all %s", linkList)
    return
}

我的期望是，当func被调用时，从长和短url生成的信息就会像在代码中那样被放入数据库。

Answer 1

如果问题是在调用addLink时没有向db添加任何内容，那么问题看起来是因为在创建和打印linkString var之后，以及在调用db.Exec之前，addLink中有一个返回语句。