Script to populate database using Mongoose gets stuck

Question

Script to populate database using Mongoose gets stuck

I'm currently dealing with the following script:

const db = require('../db')
const User = require('../models/user')

db.on('error', console.error.bind(console, 'MongoDB connection error:'))

const main = async () => {
    const users = [
        new User({ name: 'Benny', age: 28, status: 'active' }),
        new User({ name: 'Claire', age: 28, status: 'active' })
    ]
    const newUsers = async () => {
        await users.forEach(async user => await user.save())
    }
    await newUsers()
    console.log("Created users!")
}

const run = async () => {
        await main()
        process.exit(0)
}

run()

The issue I'm facing is that process.exit() seems to be running before main() completes its execution, resulting in no users being created.

If I remove process.exit(), the script runs successfully but hangs indefinitely.

So, how can I ensure that my script both executes properly and exits after completion?

javascript mongodb mongoose

Answer 1

Answer №1

Attempting to await users.forEach() is ineffective because the method forEach does not have a return value to wait for. It likely iterates through the entire list and exits immediately, leading to a premature exit from main and triggering process.exit() before the .save() operations are completed.

Instead of waiting on each individual operation, you can utilize Promise.all() to ensure all promises are resolved. This involves mapping each user creation to a Promise, which aligns with how your User.save function already operates. Here's an example implementation:

function save(user) {
  // perform async task here
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      console.log(`${user.name} Saved!`);
      resolve()
    }, 1500);
  });
}

const main = async () => {
    const users = [
        { name: 'Benny', age: 28, status: 'active' },
        { name: 'Claire', age: 28, status: 'active' }
    ]
    
    const newUsers = users.map(user => save(user));
  
    await Promise.all(newUsers);
    console.log("Created users!")
}

const run = async () => {
  await main()
  console.log("done")
}

run()

By using this approach, database calls will execute concurrently, speeding up the seeding process significantly. Instead of running operations sequentially (in order), they will occur simultaneously unless specifically required for your use case.

Answer 2

Attempting to await users.forEach() is ineffective because the method forEach does not have a return value to wait for. It likely iterates through the entire list and exits immediately, leading to a premature exit from main and triggering process.exit() before the .save() operations are completed.

Instead of waiting on each individual operation, you can utilize Promise.all() to ensure all promises are resolved. This involves mapping each user creation to a Promise, which aligns with how your User.save function already operates. Here's an example implementation:

function save(user) {
  // perform async task here
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      console.log(`${user.name} Saved!`);
      resolve()
    }, 1500);
  });
}

const main = async () => {
    const users = [
        { name: 'Benny', age: 28, status: 'active' },
        { name: 'Claire', age: 28, status: 'active' }
    ]
    
    const newUsers = users.map(user => save(user));
  
    await Promise.all(newUsers);
    console.log("Created users!")
}

const run = async () => {
  await main()
  console.log("done")
}

run()

By using this approach, database calls will execute concurrently, speeding up the seeding process significantly. Instead of running operations sequentially (in order), they will occur simultaneously unless specifically required for your use case.

Answer 3

Answer №2

One of my colleagues suggested the following solution:

const database = require('../database')
const Person = require('../models/person')

database.on('error', console.error.bind(console, 'Error connecting to MongoDB:'))

const initiate = async () => {
    const people = [
        new Person({ name: 'Alice', age: 30, status: 'active' }),
        new Person({ name: 'Bob', age: 35, status: 'inactive' })
    ]
    const addNewPeople = async () => {
        await Promise.all(people.map(async (person) => {
            await person.save()
        }))
    }
    await addNewPeople()
    console.log("People added successfully!")
}

const execute = async () => {
    await initiate()
    process.exit()
}

execute()

Answer 4

One of my colleagues suggested the following solution:

const database = require('../database')
const Person = require('../models/person')

database.on('error', console.error.bind(console, 'Error connecting to MongoDB:'))

const initiate = async () => {
    const people = [
        new Person({ name: 'Alice', age: 30, status: 'active' }),
        new Person({ name: 'Bob', age: 35, status: 'inactive' })
    ]
    const addNewPeople = async () => {
        await Promise.all(people.map(async (person) => {
            await person.save()
        }))
    }
    await addNewPeople()
    console.log("People added successfully!")
}

const execute = async () => {
    await initiate()
    process.exit()
}

execute()

Answer 5

Answer №3

Here is the solution I came up with - any tips on how to make it better?

const db = require('../db')
const User = require('../models/user')

db.on('error', console.error.bind(console, 'MongoDB connection error:'))

const main = async () => {
    const users = [
        { name: 'Benny', age: 28, status: 'active' },
        { name: 'Claire', age: 28, status: 'active' }
    ]

    await User.insertMany(users)
    console.log("Users have been added!")
}

const run = async () => {
    await main()
    db.close()
}

run()

Answer 6

Here is the solution I came up with - any tips on how to make it better?

const db = require('../db')
const User = require('../models/user')

db.on('error', console.error.bind(console, 'MongoDB connection error:'))

const main = async () => {
    const users = [
        { name: 'Benny', age: 28, status: 'active' },
        { name: 'Claire', age: 28, status: 'active' }
    ]

    await User.insertMany(users)
    console.log("Users have been added!")
}

const run = async () => {
    await main()
    db.close()
}

run()

Script to populate database using Mongoose gets stuck

Answer №1

Answer №2

Answer №3

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