Migrate Firebase Realtime Database to Firestore

Question

I am looking for the best way to migrate my apps database which is using firebase realtime database to the new Cloud Firestore database. I am confident for the project I am

Answer 1

I just did this with a very basic node script and I hope it will serve as an example to the next one having this issue:

require('firebase/firestore')
const fs = require('fs')
const { initializeApp, firestore } = require('firebase/app')

const UID = 'asdfasdf' // UID of the user you are migrating

initializeApp({
    apiKey: process.env.API_KEY,
    projectId: process.env.PROJECT_ID
})

// db.json is the downloaded copy from my firebasedatabase
fs.readFile('db.json', (err, data) => {
    if (err) throw err
    const json = JSON.parse(data)
    const readings = json.readings[UID]
    const result = Object.values(readings)
    result.forEach(({ book, chapter, date }) =>
        // In my case the migration was easy, I just wanted to move user's readings to their own collection
        firestore().collection(`users/${UID}/readings`)
            .add({ date: firestore.Timestamp.fromDate(new Date(date)), chapter, book })
            .catch(console.error)
    )
    console.log('SUCCESS!')
})

Of course you can also iterate twice to do it for every user but in my case it was not needed :)