php小编子墨在这里为大家解答一个常见的问题：如果在不同模块中访问数据库，应该如何操作呢？在开发过程中，我们经常需要在不同的功能模块中访问数据库，这涉及到如何管理数据库连接和执行数据库操作的问题。为了解决这个问题，我们可以采用多种方式，例如使用全局变量、单例模式、依赖注入等。具体选择哪种方式取决于项目的需求和开发团队的习惯。接下来，我将对这些方式进行详细介绍，希望能帮助到大家。
问题内容
我尝试使用 jwt 进行 atuhorize，但遇到问题，当我检查来自声明的有价值电子邮件的电子邮件时，我收到错误 500。这个问题是因为数据库尚未准备好。
这是代码
套餐路线
package route
import (
"go_fiber/controller"
"go_fiber/middleware"
"github.com/gofiber/fiber/v2"
)
func routeinit(app *fiber.app, usercontroller controller.usercontroller) {
app.get("/users", middleware.authmiddleware, usercontroller.findall)
app.post("/login", usercontroller.login)
}打包应用
package app
import (
"database/sql"
"fmt"
"go_fiber/helper"
"os"
"time"
_ "github.com/go-sql-driver/mysql"
"github.com/joho/godotenv"
)
func newdb() *sql.db {
var (
username = envvariable("db_username")
password = envvariable("db_password")
host = envvariable("db_host")
port = envvariable("db_port")
db_name = envvariable("db_name")
)
dns := fmt.sprintf("%s:%s@tcp(%s:%s)/%s?parsetime=true", username, password, host, port, db_name)
db, err := sql.open("mysql", dns)
if err != nil {
panic(err)
}
db.setmaxidleconns(10)
db.setmaxopenconns(100)
db.setconnmaxidletime(5 * time.minute)
db.setconnmaxlifetime(60 * time.minute)
return db
}包主
package main
import (
"go_fiber/app"
"go_fiber/controller"
"go_fiber/exception"
"go_fiber/repository"
"go_fiber/route"
"go_fiber/service"
"github.com/go-playground/validator/v10"
"github.com/gofiber/fiber/v2"
)
func main(){
var db = app.newdb()
app := fiber.new()
app.use(func(c *fiber.ctx) error {
defer func() {
if err := recover(); err != nil {
exception.errorhandler(c, err)
}
}()
return c.next()
})
validator := validator.new()
userrepository := repository.newuserrepository()
userservice := service.newuserservice(userrepository, db, validator)
usercontroller := controller.newusercontroller(userservice)
route.routeinit(app, usercontroller)
app.listen(":3000")
}封装中间件
package middleware
import (
"database/sql"
"errors"
"fmt"
"go_fiber/exception"
"log"
"os"
"time"
"github.com/gofiber/fiber/v2"
"github.com/golang-jwt/jwt/v4"
)
func authmiddleware(c *fiber.ctx) error{
tokenstring := c.cookies("authorization")
log.printf("(middleware) token : %v", tokenstring)
if tokenstring == "" {
panic(exception.newuserunauthorized(errors.new("user unauthorized").error()))
}
token, err := jwt.parse(tokenstring, func(token *jwt.token) (interface{}, error) {
if _, ok := token.method.(*jwt.signingmethodhmac); !ok {
return nil, fmt.errorf("unexpected signing method :%v", token.header["sub"])
}
return []byte(os.getenv("secret")), nil
})
log.printf("(middleware) token : %v", token)
log.printf("(middleware) error : %v", err)
if claims, ok := token.claims.(jwt.mapclaims); ok && token.valid {
if float64(time.now().unix()) > claims["exp"].(float64) {
panic(exception.newuserunauthorized(errors.new("user unauthorized").error()))
}
log.printf("(middleware) claims : %v", claims)
log.printf("(middleware) ok : %v", ok)
var db *sql.db
tx, err := db.begin()
log.printf("(middleware) tx : %v", tx)
log.printf("(middleware) error : %v", err)
query :=`
select email from users
where email = ?
limit 1
`
log.printf("(middleware) query : %v", query)
user, err := tx.querycontext(c.context(), query, claims["sub"])
log.printf("(middleware) user : %v", user)
log.printf("(middleware) error : %v", err)
if err != nil {
panic(exception.newuserunauthorized(errors.new("user unauthorized").error()))
}
c.locals("user", user)
c.next()
}else {
panic(exception.newuserunauthorized(errors.new("user unauthorized").error()))
}
return nil
}这部分是问题代码
var db *sql.db
tx, err := db.begin()
log.printf("(middleware) tx : %v", tx) // no detect in terminal这是日志的输出
2023/02/12 10:00:04 (middleware) token : eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE2NzYxNzEzOTIsInN1YiI6IkphZmFyQGdtYWlsLmNvbSJ9.6nn_IaNACHfe7flFMOXfj1ygZS-U_yrnU_Gvjn8xCp8
2023/02/12 10:00:04 (middleware) token : &{eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE2NzYxNzEzOTIsInN1YiI6IkphZmFyQGdtYWlsLmNvbSJ9.6nn_IaNACHfe7flFMOXfj1ygZS-U_yrnU_Gvjn8xCp8 0xc0000a6780 map[alg:HS256 typ:JWT] map[exp:1.676171392e+09 sub:[email protected]] 6nn_IaNACHfe7flFMOXfj1ygZS-U_yrnU_Gvjn8xCp8 true}
2023/02/12 10:00:04 (middleware) error :
2023/02/12 10:00:04 (middleware) claims : map[exp:1.676171392e+09 sub:[email protected]]
2023/02/12 10:00:04 (middleware) ok : true 那么，如果不同的包如何解决访问数据库的问题？
解决方法
您应该通过路由注册将数据库处理程序向下传递到中间件。
更改您的 authmiddleware，以便它由采用 db *sql.db 作为参数的函数返回：
func newauthmiddleware(db *sql.db) fiber.handler {
return func(c *fiber.ctx) error {
// the rest of your function is here and has access to db
}
}然后您需要在 routeinit 函数中调用 newauthmiddleware
func routeinit(app *fiber.app, usercontroller controller.usercontroller, db *sql.db) {
app.get("/users", middleware.newauthmiddleware(db), usercontroller.findall)
app.post("/login", usercontroller.login)
}然后在主函数中将数据库传递给 routeinit()
func main() {
// ... as before
route.RouteInit(app, userController, db)
}以上就是如果功能在不同模块中如何访问数据库？的详细内容，更多请关注编程网其它相关文章！
