Firebase Cheatsheet

A cheatsheet for using firebase

Table of Contents

• Authentication
• Security Rules
• Firestore
• Realtime Database
• Functions
• Cloud Storage
• Hosting

Notes

• Avoiding Vendor lockin by creating wrapper function for every firebase function used

• Use Firestore for more when you have more complex data to store and have to make less requests (< 50K requests)

• Use Realtime Database when you have less data and have to make a lot of frequent requests (> 50K requests)

• Copy your Firebase web app's Firebase configuration and paste in a global JS file or your index.html file

Authentication

import 'firebase/auth';

There are 5 main auth functions:

Firebase Create User

With email and password

await firebase.auth().createUserWithEmailAndPassword(email, password);

Firebase Signin

await firebase.auth().signInWithEmailAndPassword(email, password);

Firebase Signout

await firebase.auth().signOut()

Firebase Auth Listener

let unsubscribe = firebase.auth().onAuthStateChanged(callback);

// unsubscribe function clears the listener and callback function takes a user parameter

Firebase Current User

firebase.auth().currentUser;
// return user or null

Security Rules

Security Rules controls who can and can't read and write data into firebase databases and storage.

Cloud Firestore and Cloud Storage syntax

rules_version = '2'; // Latest version here
service <<name>> {
    match <<path>> {
        allow <<methods>> : if <<condition>>
    }
}

Cloud Firestore example

rules_version = '2';
service cloud.firestore {
    match /database/{database}/documents {
        match /{document=**}{
            allow write : if false;
            allow read: if request.auth.uid !== null;
        }

        match /users/{userId} {
            allow write: if request.auth.uid == userId;
        }
    }
}

Realtime Database syntax

{
    "rules": {
        "<<path>>": {
            ".read": <<condition>>,
            ".write": <<condition>>,
            ".validate": <<condition>>
            "<<path>>": {
                "<<path>>": {
                    ".read": <<condition>>,
                    ".write": <<condition>>
                }
            }
        }
    }
}

Realtime Database example

{
    "rules": {
        ".read": "true",
        ".write": "auth!=null",
        "posts": {
            "$userId": {
                "$postId": {
                    ".write": true
                }
            }
        } 
    }
}

Learn the Firebase Security Rules Language here.

Firestore

import 'firebase/firestore';

Collection Reference

let ref = firebase.firestore().collection(collectionName)

Specifing a document

let doc = firebase.firestore().collection(collectionName).doc(docId)

Getting Firestore data

Get the data of a document

let getData = await ref.doc(docId).get();
let data = getData.exists ? getData.data() : null;

Get all the data of a collection

let allData = await ref.get();
allData.forEach(doc => // doc.id & doc.data());

Setting Firestore data

Adding data to a collection

await ref.add(data);

Setting data to a document

await ref.doc(docId).set(data);

Updating Firestore data

Updating collection data

await ref.doc(docId).update(updatedData);

Deleting Firestore data

Deleting a document

await ref.doc(docId).delete();

Deleting a field

let removefield = ref.update({
    fieldName: firebase.firestore.FieldValue.delete()
});

Conditions

let queryData = await ref.where('key', 'condition', 'value').get();

queryData.forEach(doc => // doc.id & doc.data());

Ordering and Limiting

await ref.orderBy("field", "desc").limit(num).get();

Get realtime updates

Realtime updates of a collection

ref.onSnapshot(results => {
    results.map/foreach(doc => // doc.id & doc.data())
});

Realtime updates of a document

doc.onSnapshot(doc => // doc.id & doc.data());

Transactions and Batches

// ...

Realtime Database

Functions

Setup

Type 'firebase init' and select 'Functions' and follow the required steps in the terminal

To deploy use 'firebase deploy'

Cloud Storage

Hosting