node.js - 如何摆脱 Node Mongo Express 应用程序中的 UnhandledPromiseRejectionWarning
问题描述
问候!
我有一个 Node-Express 端点,它调用 addAdminController.js(附在下面)来创建一个新管理员。
从功能的角度来看,一切都很好。但是,当您使用 mongoose FindOne 方法检查用户是否已经存在时,它会在控制台上留下警告。但是,这并不会阻止函数运行,并且我成功地将“电子邮件已在使用中”作为 Postman 中的 json 对象返回。
我想知道为什么我会看到这个错误,以及我在处理 Promise 时做错了什么。非常感谢您的帮助。
addAdminController.js
const adminsModel = require("../../../../models/admins");
const bcrypt = require("bcryptjs");
exports.addAdminController = async (req, res, next) => {
const { name, email, password, role, image, status } = req.body;
//check if user already exists
try {
adminsModel
.findOne({ email }, (err, admin) => {
if (admin) {
res.status(400).json("Email Already in use");
return;
}
})
.exec();
} catch (error) {
return res.status(500).json("Something Went Wrong");
}
//Encrypt Password using Bcrypt
const saltRounds = 12;
const hashPass = bcrypt.hashSync(password, saltRounds);
//Create New Model with Hashed Password
const newAdmin = new adminsModel({
name: name,
email: email,
password: hashPass,
role: role,
image: image,
status: status,
});
// Save new admin user.
try {
await newAdmin.save();
res.json(newAdmin);
return;
} catch (error) {
res.status(400).json("There was an error creating admin user");
}
};
控制台警告
node:18700) UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
at ServerResponse.setHeader (_http_outgoing.js:533:11)
at ServerResponse.header (F:07_Developrs\Github\APIv2\node_modules\express\lib\response.js:771:10)
at ServerResponse.send (F:07_Developrs\Github\APIv2\node_modules\express\lib\response.js:170:12)
at ServerResponse.json (F:\07_Developrs\Github\APIv2\node_modules\express\lib\response.js:267:15)
at exports.addAdminController (F:\07_Developrs\Github\APIv2\routes\api\admins\addAdmin\addAdmin.controller.js:37:19)
at processTicksAndRejections (internal/process/task_queues.js:97:5)
(Use `node --trace-warnings ...` to show where the warning was created)
(node:18700) 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:18700) [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.
解决方案
首先,您不应该使用函数的回调版本,findOne
因为findOne
函数调用下面的代码将在执行回调之前findOne
执行。
由于findOne
函数调用下面的代码取决于用户是否已经存在,await
因此adminsModel.findOne(...)
检查findOne
函数的结果是否返回了用户。
其次,findOne
用块包装函数调用try-catch
来处理被拒绝的承诺。
try {
const user = await adminsModel.findOne({ email });
if (user) {
return res.status(400).json("Email Already in use");
}
// code to run if user doesn't exists
} catch (error) {
return res.status(500).json("Something Went Wrong");
}
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