node.js - 我在连接到 mongodb 和 express 时出错，我的终端发疯了

Question

这是错误。快把我炸了请帮忙。
它只是因为一些不受支持的东西而生我的气。它对我大喊大叫不支持。我从未在终端中看到过那么多错误。谁能告诉我为什么我得到这个。

  DeprecationWarning: current Server Discovery and Monitoring engine is 

deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to the MongoClient constructor.
Server running on port 300
(node:6452) UnhandledPromiseRejectionWarning: MongooseError: Can't call `openUri()` on an active connection with different connection strings. Make sure you aren't calling `mongoose.connect()` multiple times. See: https://mongoosejs.com/docs/connections.html#multiple_connections    at NativeConnection.Connection.openUri (C:\Users\hp\Documents\short shortnner-backend\node_modules\mongoose\lib\connection.js:682:13)
    at C:\Users\hp\Documents\short shortnner-backend\node_modules\mongoose\lib\index.js:342:10
    at C:\Users\hp\Documents\short shortnner-backend\node_modules\mongoose\lib\helpers\promiseOrCallback.js:31:5
    at new Promise (<anonymous>)
    at promiseOrCallback (C:\Users\hp\Documents\short shortnner-backend\node_modules\mongoose\lib\helpers\promiseOrCallback.js:30:10)
    at Mongoose.connect (C:\Users\hp\Documents\short shortnner-backend\node_modules\mongoose\lib\index.js:341:10)
    at Object.<anonymous> (C:\Users\hp\Documents\short shortnner-backend\models\Url.js:10:27)    at Module._compile (internal/modules/cjs/loader.js:1138:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1158:10)
    at Module.load (internal/modules/cjs/loader.js:986:32)
    at Function.Module._load (internal/modules/cjs/loader.js:879:14)
    at Module.require (internal/modules/cjs/loader.js:1026:19)
    at require (internal/modules/cjs/helpers.js:72:18)
    at Object.<anonymous> (C:\Users\hp\Documents\short shortnner-backend\routes\url.js:7:13) 
    at Module._compile (internal/modules/cjs/loader.js:1138:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1158:10)
(node:6452) 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:6452) [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. DeprecationWarning: current Server Discovery and Monitoring engine is deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to the MongoClient constructor.
Server running on port 300
(node:6452) UnhandledPromiseRejectionWarning: MongooseError: Can't call `openUri()` on an active connection with different connection strings. Make sure you aren't calling `mongoose.connect()` multiple times. See: https://mongoosejs.com/docs/connections.html#multiple_connections    at NativeConnection.Connection.openUri (C:\Users\hp\Documents\short shortnner-backend\node_modules\mongoose\lib\connection.js:682:13)
    at C:\Users\hp\Documents\short shortnner-backend\node_modules\mongoose\lib\index.js:342:10
    at C:\Users\hp\Documents\short shortnner-backend\node_modules\mongoose\lib\helpers\promiseOrCallback.js:31:5
    at new Promise (<anonymous>)
    at promiseOrCallback (C:\Users\hp\Documents\short shortnner-backend\node_modules\mongoose\lib\helpers\promiseOrCallback.js:30:10)
    at Mongoose.connect (C:\Users\hp\Documents\short shortnner-backend\node_modules\mongoose\lib\index.js:341:10)
    at Object.<anonymous> (C:\Users\hp\Documents\short shortnner-backend\models\Url.js:10:27)    at Module._compile (internal/modules/cjs/loader.js:1138:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1158:10)
    at Module.load (internal/modules/cjs/loader.js:986:32)
    at Function.Module._load (internal/modules/cjs/loader.js:879:14)
    at Module.require (internal/modules/cjs/loader.js:1026:19)
    at require (internal/modules/cjs/helpers.js:72:18)
    at Object.<anonymous> (C:\Users\hp\Documents\short shortnner-backend\routes\url.js:7:13) 
    at Module._compile (internal/modules/cjs/loader.js:1138:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1158:10)
(node:6452) 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:6452) [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.
 MongoDB Connected...

这是我的 code 的链接

Answer 1

这都是关于 mongo 连接的:

您的参数传递给 mongoose.connect在 ./models/url.js不正确:

mongoose.connect 的第一个参数是一个 mongo 连接字符串，第二个是一个选项(传递给 mongo.connect)或一个回调，应该是这样的

module.exports = mongoose.connect('mongodb://user:pass@localhost:port/database', { useNewUrlParser: true });

你可以在这里找到它的官方文档: https://mongoosejs.com/docs/api/mongoose.html#mongoose_Mongoose-connect

请记住 mongoose.connect是一个异步函数，使用 require("../models/Url")在 ./routes/url.js会导致意想不到的结果。