NextJsTypeError：無法讀取未定義的屬性（讀取“0”）-有解無憂

我正在嘗試連接到 Mongodb 來定義連接、斷開連接并在 API 中使用它。我收到無法讀取未定義屬性的 TypeError（讀取 '0）。我通過控制臺檢查是否包含與此 Mongoose 實體關聯的所有連接但只有 0 而不是連接串列的陣列。以下是代碼片段。

import mongoose from 'mongoose';

const connection = {};

async function connect() {
  if (connection.isConnected) {
    console.log('already connected');
  }
  if (mongoose.connections.length > 0) {
    connection.isConnected = mongoose.connections[0].readyState;
    console.log('cone', connection.isConnected);
    if (connection.isConnected === 1) {
      console.log('use previous connection');
      return;
    }
    await mongoose.disconnect();
  }
  const dbConnect = mongoose.connect(process.env.MONGODB_URI, {
    //   useNewUrlParser: true,
    useUnifiedTopology: true,
    //   useCreateIndex: true,
  });
  console.log('new connection');
  connection.isConnected = dbConnect.connections[0].readyState;
}
async function disconnect() {
  if (connection.isConnected) {
    if (process.env.NODE_ENV === 'production') {
      await mongoose.disconnect();
      connection.isConnected = false;
    } else {
      console.log('not disconnected');
    }
  }
}
const db = { connect, disconnect };
export default db;

我得到的錯誤是這個

error - (api)\utils\db.js (25:49) @ Object.connect
TypeError: Cannot read properties of undefined (reading '0')
  23 |   });
  24 |   console.log('new connection');
> 25 |   connection.isConnected = dbConnect.connections[0].readyState;
     |                                                 ^
  26 |   console.log("cone1", connection.isConnected);
  27 | }

uj5u.com熱心網友回復：

mongoose.connect() 上沒有型別作為連接。所以只需要洗掉我正在尋找的connections[0].readyState。

import mongoose from 'mongoose';

const connection = {};

async function connect() {
  if (connection.isConnected) {
    console.log('already connected');
    return;
  }
  if (mongoose.connections.length > 0) {
    connection.isConnected = mongoose.connections[0].readyState;
    if (connection.isConnected === 1) {
      console.log('use previous connection');
      return;
    }
    await mongoose.disconnect();
  }
  const options = {
    useUnifiedTopology: true,
    useNewUrlParser: true,
  };
  const uri = process.env.MONGODB_URI;
  const db = mongoose.connect(uri, options);
  console.log('new connection');
  connection.isConnected = db

  if (!uri) {
    throw new Error('Add your Mongo URI to .env');
  }
}

async function disconnect() {
  if (connection.isConnected) {
    if (process.env.NODE_ENV === 'production') {
      await mongoose.disconnect();
      connection.isConnected = false;
    } else {
      console.log('not disconnected');
    }
  }
}
const db_export = { connect, disconnect };
export default db_export;

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標籤：mongodb 猫鼬下一个.js

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