使用`let cached = global.mongoose`时出现Next.js + Typescript + mongoose错误

Question

我试图为 Next.js + Typescript 应用程序创建一个缓存的猫鼬连接，但使用的是：

let cached = global.mongoose;

if (!cached) {
  cached = global.mongoose = { conn: null, promise: null };
}

global.mongoose 显示以下错误：

Element implicitly has an 'any' type because type 'typeof globalThis' has no index signature.ts(7017)

编辑： 这是完整的/lib/dbConnect.ts 文件

import mongoose, { Connection } from "mongoose";

const MONGODB_URI: string = process.env.MONGODB_URI!;

if (!MONGODB_URI) {
  throw new Error(
    "Please define the MONGODB_URI environment variable inside .env.local"
  );
}

let cached = global.mongoose;

if (!cached) {
  cached = global.mongoose = { conn: null, promise: null };
}

async function dbConnect() {
  if (cached.conn) {
    return cached.conn;
  }

  if (!cached.promise) {
    const opts = {
      bufferCommands: false,
    };

    cached.promise = mongoose.connect(MONGODB_URI, opts).then((mongoose) => {
      return mongoose;
    });
  }
  cached.conn = await cached.promise;
  return cached.conn;
}

export default dbConnect;

Answer 1

由于您在技术上扩展了全局上下文，因此您需要添加它的新类型。

对于没有类型的包，我通常在根文件夹中有一个custom.d.ts。

在你的情况下：

declare global {
  const mongoose: any
}

另外，不要忘记在tsconfig.json 中添加custom.d.ts：

{
  "compilerOptions": {...},
  "include": ["...your other files", "custom.d.ts"],
}

Prisma 连接参考：https://stackoverflow.com/a/69434850/14122260

Answer 2

作为 Prisma 链接：

创建一个新文件 utils/global.d.ts

import { Connection } from 'mongoose'

declare global {
    var mongoose: any
}

export const mongoose = global.mongoose || new Connection()

if (process.env.NODE_ENV !== 'production') global.mongoose = mongoose

在 tsconfig.json 中添加包含：

...
"include": ["next-env.d.ts", "utils/global.d.ts", "**/*.ts", "**/*.tsx"],
...

dbConnect.js：

import mongoose from 'mongoose'

const MONGODB_URI : string = process.env.MONGODB_URI || ''

if (!MONGODB_URI) {
    throw new Error(
        'Please define the MONGODB_URI environment variable inside .env.local'
    )
}

/**
 * Global is used here to maintain a cached connection across hot reloads
 * in development. This prevents connections growing exponentially
 * during API Route usage.
 */
let cached = global.mongoose

if (!cached) {
    cached = global.mongoose = { conn: null, promise: null }
}

async function dbConnect() {
    if (cached.conn) {
        return cached.conn
    }

    if (!cached.promise) {
        const opts = {
            bufferCommands: false,
        }


        cached.promise = mongoose.connect(MONGODB_URI, opts).then((mongoose) => {return mongoose});
    }
    cached.conn = await cached.promise
    return cached.conn
}

export default dbConnect

未经测试

Answer 3

我在您的文件中没有发现任何特别错误，也许检查您的文件是否在正确的目录中，以及您的 .env.local 文件。

这是我在上一个项目中使用的lib/dbConnect.js，仅供参考。

import mongoose from 'mongoose';

const MONGODB_URI = process.env.MONGODB_URI;

if (!MONGODB_URI) {
  throw new Error(
    'Please define the MONGODB_URI environment variable inside .env.local';
  )
}

let cached = global.mongoose;

if (!cached) {
  cached = global.mongoose = { conn: null, promise: null }
}

async function dbConnect () {
  if (cached.conn) {
    return cached.conn
  }

  if (!cached.promise) {
    const opts = {
      useNewUrlParser: true,
      useUnifiedTopology: true,
      bufferCommands: false,
      bufferMaxEntries: 0,
      useFindAndModify: true,
      useCreateIndex: true
    }

    cached.promise = mongoose.connect(MONGODB_URI, opts).then(mongoose => {
      return mongoose
    })
  }
  cached.conn = await cached.promise
  return cached.conn
}

export default dbConnect