Mongoose.connect not throwing any error, when Mongodb is not running

Question

Solved: if anybody is interested, it seems that MongoDB is just starting automatically on Windows startup...

I have this function to initialize a Mongoose connection:

const mongoose = require('mongoose');

let db;

async function initDD(){
    try {
       db  = await  mongoose.connect('mongodb://localhost:27017/local', { useNewUrlParser: true });   

    } catch (error) {
        console.log('mongoose error',error)//Doesn't come to this...
    }

}

This promise doesn't get rejected, even if i haven't started my MongoDB service yet. I tried also the callback version- same result. I clearly do not have any MongoDB running, and yet Mongoose "connects" as if nothing is wrong.

What could be the problem here? I have a standard MongoDB setup, latest Mongoose, Windows 7 and Node 10.

Edit: the logged value of the "db", when no MogoDB is running:

Mongoose {
  connections:
   [ NativeConnection {
       base: [Circular],
       collections: [Object],
       models: [Object],
       config: [Object],
       replica: false,
       options: null,
       otherDbs: [],
       relatedDbs: {},
       states: [Object],
       _readyState: 1,
       _closeCalled: false,
       _hasOpened: true,
       plugins: [],
       _listening: false,
       _connectionOptions: [Object],
       name: 'local',
       host: 'localhost',
       port: 27017,
       user: undefined,
       pass: undefined,
       client: [MongoClient],
       '$initialConnection': [Promise],
       db: [Db] } ],
  models: { User: Model { User } },
  modelSchemas:
   { User:
      Schema {
        obj: [Object],
        paths: [Object],
        aliases: {},
        subpaths: {},
        virtuals: [Object],
        singleNestedPaths: {},
        nested: {},
        inherits: {},
        callQueue: [],
        _indexes: [],
        methods: {},
        methodOptions: {},
        statics: {},
        tree: [Object],
        query: {},
        childSchemas: [],
        plugins: [Array],
        '$id': 1,
        s: [Object],
        _userProvidedOptions: {},
        options: [Object],
        '$globalPluginsApplied': true } },
  options: { pluralization: true, [Symbol(mongoose:default)]: true },
  _pluralize: [Function: pluralize],
  Schema:
   { [Function: Schema]
     reserved:
      [Object: null prototype] {
        populated: 1,
        remove: 1,
        validate: 1,
        toObject: 1,
        schema: 1,
        save: 1,
        modelName: 1,
        get: 1,
        isNew: 1,
        isModified: 1,
        init: 1,
        errors: 1,
        db: 1,
        collection: 1,
        removeListener: 1,
        listeners: 1,
        once: 1,
        on: 1,
        emit: 1,
        prototype: 1 },
     Types:
      { String: [Function],
        Number: [Function],
        Boolean: [Function],
        DocumentArray: [Function],
        Embedded: [Function: SingleNestedPath],
        Array: [Function],
        Buffer: [Function],
        Date: [Function],
        ObjectId: [Function],
        Mixed: [Function],
        Decimal: [Function],
        Decimal128: [Function],
        Map: [Function: Map],
        Oid: [Function],
        Object: [Function],
        Bool: [Function],
        ObjectID: [Function] },
     ObjectId:
      { [Function: ObjectId]
        schemaName: 'ObjectId',
        get: [Function],
        _checkRequired: [Function],
        _cast: [Function: castObjectId],
        cast: [Function: cast],
        checkRequired: [Function] } },
  model: [Function],
  plugins:
   [ [ [Function], [Object] ],
     [ [Function], [Object] ],
     [ [Function], [Object] ],
     [ [Function], [Object] ] ] }

Answer 1

I have Windows too. Once Mongo is installed it runs in the background and it's fine, otherwise you'd have to start manually a mongod instance each time.

I prefer to use then/catch even if try/catch is now supported:

mongoose.connect(
        'mongodb://localhost:27017/test',{
            useNewUrlParser: true,
            useCreateIndex: true,
            useFindAndModify: false,
            useUnifiedTopology: true
        }
    )
    .then(() => console.log('DB Connection Successfull'))
    .catch((err) => {
        console.error(err);
    });

If you don't want to buffer your models, thus getting confusing behaviour, you need to disable it either on your schema or globally:

https://mongoosejs.com/docs/guide.html#bufferCommands https://mongoosejs.com/docs/connections.html#buffering

reference: mongoose docs

Answer 2

I'm not sure. but I think you should execute the function. await initDD (). It is little code to understand what happens.

something like that

//database.js

const mongoose = require("mongoose");
  async function connect() {
  await mongoose.connect(process.env.DATABASE_SERVER, {
   useNewUrlParser: true
  });
  if (mongoose.connection.readyState === 1) {
   console.log("Successfully connected to database");
  }
 }
module.exports = { connect };

// index.js

const app = require("./app");
const { connect } = require("./database");
async function main() {
 // dayabase conexion
 await connect();
 // start server
 const port = process.env.PORT || 4000;
 await app.listen(port, () => console.log(`Server on port ${port} `));
}
main();

replace process.env.DATABASE_SERVER, with 'mongodb://localhost:27017/local'