/firestore-9-cheatsheet

Firestore 9 cheatsheet

Table of contents

Initialization

import { initializeApp } from "firebase/app";
import { getFirestore } from "firebase/firestore";

const config = {
  apiKey: "xxxx",
  authDomain: "xxxx",
  projectId: "xxxx",
  storageBucket: "xxxx",
  messagingSenderId: "xxxx",
  appId: "xxxx",
};


export const app = initializeApp(config);
export const db = getFirestore(app);

Read doc/docs

Read collection

const collectionRef = collection(db, "users");

getDocs(collectionRef).then((snapshot) => {
  snapshot.docs.forEach((doc) => {
    console.log(doc.data());
  });
});

Read a single document

const docRef = doc(db, "users", "G3OIFQ7qes9Rhc74XfRA");
// - OR
// const docRef = doc(db, "users/G3OIFQ7qes9Rhc74XfRA");

getDoc(docRef).then((snapshot) => {
  console.log(snapshot.data());
});

Check a document exists or not

const docSnap = await getDoc(docRef);

if(!docSnap.exists()) {
  console.log("Document does not exist!");
}

Conditionally querying data

const collectionRef = collection(db, "users");
const q = query(collectionRef, where("username", "==", "kingrayhan"));

const snapshot = await getDocs(q);
console.log(snapshot.docs[0].data());





// -- More query example
const stateQuery = query(citiesRef, where("state", "==", "CA"));
const populationQuery = query(citiesRef, where("population", "<", 100000));
const nameQuery = query(citiesRef, where("name", ">=", "San Francisco"));

Query operator

  • < - less than
  • <= - less than or equal to
  • == - equal to
  • > - greater than
  • >= - greater than or equal to
  • != - not equal to
  • array-contains
  • array-contains-any
  • in
  • not-in

Store data

Store a doc with auto generated id

const collectionRef = collection(db, "users");
const docRef = await addDoc(collectionRef, {
  username: "johndoe",
  avatar: "https://avatars0.githubusercontent.com/u/174825?v=4",
});

console.log(docRef.id);

Store a doc with custom id

const docRef = doc(db, "users", "user-id-custom");
// - OR
// const docRef = doc(db, "users/G3OIFQ7qes9Rhc74XfRA");

await setDoc(docRef, {
  username: "kingrayhan",
  avatar: "https://avatars0.githubusercontent.com/u/174825?v=4",
});

Deleting document

Delete a document with id

const docRef = doc(db, "users", "xj7lxm0OGObV91xn3tE0");
await deleteDoc(docRef);

Update document

const docRef = doc(db, "users", "AvPfqaJs4hCmqpk0RUjU");
// - OR
// const docRef = doc(db, "users/G3OIFQ7qes9Rhc74XfRA");


/**
 * Update document
 */
await updateDoc(docRef, {
  name: "Rayhan",
  username: "rayhan",
});

/**
 * Override the whole document
 */
await setDoc(docRef, {
  x: 10,
});

Sorting/limiting

Get limited number of docs

const colRef = collection(db, "posts");

const q = query(colRef, limit(5))
const postsSnap = await getDocs(q)

const posts = postsSnap.docs.map((post) => post.data())

// -> console.log(posts)

Limit with order

const colRef = collection(db, "posts");

const q = query(colRef, limit(5), orderBy("createdAt", "desc"))
const postsSnap = await getDocs(q)

const posts = postsSnap.docs.map((post) => post.data())

// -> console.log(posts)