Mongoose import for TypeScript not working

Question

New for Node and Typescript. I get an error that mongoose.connect is not a function when tsc starts.

I have the following code:

import express = require('express');
import * as mongoose from "mongoose";

/** Routes for the app */
import apiUserRouter from "./api/user"

class App{

   public express :express.Application


    constructor() {
        this.express = express()
        this.setupDb();
    }

    private setupDb() : void {
        var mongoDb = 'mongodb://127.0.0.1/my_database';
        mongoose.connect(mongoDb);
        var db = mongoose.connection;
        db.on('error', console.error.bind(console, 'MongoDB Connection error'));
    }
}

If i change

import * as mongoose from "mongoose"

to

import mongoose = require('mongoose');

Then everything works fine.

I run the following npm command for types, as I understand that this should fix the problem.

npm install @types/mongoose --save

Edit: adding my packages.json

{
    "name": "nodejs-ts-test2",
    "version": "1.0.0",
    "description": "",
    "main": "index.js",
    "scripts": {
        "test": "echo \"Error: no test specified\" && exit 1"
    },
    "author": "",
    "license": "ISC",
    "devDependencies": {
        "@types/express": "^4.11.1",
        "@types/mongoose": "^5.0.3",
        "typescript": "^2.7.2"
    },
    "dependencies": {
        "express": "^4.16.2",
        "mongoose": "^5.0.7"
    }
}

and tsconfig.json:

{
    "compilerOptions": {
        "target": "es2015",
        "module": "commonjs",
        "outDir": "dist",
        "strict": true,
        "noImplicitAny": false,
        "esModuleInterop": true,
        "allowSyntheticDefaultImports": true
    }
}

Answer 1

Since you did not share your package package.json or tsconfig, it was impossible to tell where the error was. So I created a new project for the code that you shared so that the error does not occur. Compare the files I use with the ones you have to narrow down the problem.

package.json

{
  "name": "mong_type",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "@types/express": "^4.11.1",
    "@types/mongoose": "^5.0.3",
    "typescript": "^2.7.2"
  },
  "dependencies": {
    "express": "^4.16.2",
    "mongoose": "^5.0.7"
  }
}

tsconfig.json

{
  "compilerOptions": {
    "target": "es2015",
    "module": "commonjs",
    "outDir": "./dist",
    "strict": true,
    "allowSyntheticDefaultImports": true,
    "esModuleInterop": true
  },
  "include": ["src"]
}

Src / app.ts

import express from "express";
import mongoose from "mongoose";

class App {
  public express: express.Application;

  constructor() {
    this.express = express();
    this.setupDb();
  }

  private setupDb(): void {
    var mongoDb = "mongodb://127.0.0.1/my_database";
    mongoose.connect(mongoDb);
    var db = mongoose.connection;
    db.on("error", console.error.bind(console, "MongoDB Connection error"));
  }
}