节点和护照处理用户名已经存在

Question

我正在尝试让我的代码处理已存在的用户名。我知道 passport 会使用 console.log(err) 自动执行此操作，但是，如果发生这种情况，我想向用户发送一条消息，因此我需要添加更多代码来执行此操作。它似乎有效，但是，当我以这种方式实现我的代码时，我遇到了很多控制台错误，我想避免将来出现任何错误。这是我的代码：

router.post("/", isLoggedIn, isAdministrator, async function(req, res){ 
    let users = [];
    let newUser = new User({
        username: req.body.user["username"],
        first_name: req.body.user["first_name"],
        middle_name: req.body.user["middle_name"],
        last_name: req.body.user["last_name"],
        email_address: req.body.user["email_address"],
        phone_number: req.body.user["phone_number"],
        street: req.body.user["street"],
        city: req.body.user["city"],
        state: req.body.user["state"],
        zip: req.body.user["zip"],
        user_permissions: req.body.user["user_permissions"],
    });
    try {
        users = await User.find({});
    }
    catch (err) {console.log(err);} 

    users.forEach(function(user) {
        if (user.username == newUser.username){
        // flash username already exists
        console.log("User Already Exists")
        return res.redirect("/users/add");
        }
    });
// If username does not exist
    try {
        await User.register(newUser, req.body.user["password"]);
    }
    catch (err) {console.log(err);} 

    res.redirect("/users");
});

这是控制台记录的内容

User Already Exists
ctor [UserExistsError]: A user with the given username is already registered
    at ...\node_modules\passport-local-mongoose\index.js:237:17
    at processTicksAndRejections (internal/process/task_queues.js:97:5)
    at async ...\routes\users.js:93:3
(node:4780) UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
    at ServerResponse.setHeader (_http_outgoing.js:518:11)
    at ServerResponse.header (...\node_modules\express\lib\response.js:771:10)
    at ServerResponse.location (...\node_modules\express\lib\response.js:888:15)
    at ServerResponse.redirect (...\node_modules\express\lib\response.js:926:18)
    at ...\routes\users.js:97:6
    at processTicksAndRejections (internal/process/task_queues.js:97:5)
(node:4780) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:4780) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

正如我所说，这段代码的逻辑仍然可以正常工作，但我担心代码的承诺拒绝部分。它似乎仍在尝试处理最后一行中的最后一个 res.redirect("/users")，尽管我之前已经返回了 res.redirect。这是有原因的吗，我应该担心吗？如果没有我单独的 forEach 循环，如果用户名已经存在使用护照，是否有更好的实现闪存的方法？谢谢

Answer 1

这不是您问题的答案，但我觉得有必要提一下：

users.forEach(function(user) {
   if (user.username == newUser.username){
    // flash username already exists
    console.log("User Already Exists")
    return res.redirect("/users/add");
   }
});

为什么不让数据库系统为您执行上述操作，而不是遍历内存中的用户列表？像这样：

users = await User.find({ username: { $eq: newUser.username }});

节点和护照处理用户名已经存在

Node and Passport Handling Username Already Existing

javascript

node.js

express

passport.js