firebase-practice.js

const { initializeApp } = require("firebase/app");
const {
  getFirestore,
  addDoc,
  setDoc,
  doc,
  getDoc,
  getDocs,
  writeBatch,
  collection,
} = require("firebase/firestore");

require("dotenv").config();

const firebaseConfig = {
  apiKey: process.env.FIREBASE_API_KEY,
  authDomain: process.env.FIREBASE_AUTH_DOMAIN,
  projectId: process.env.FIREBASE_PROJECT_ID,
  storageBucket: process.env.FIREBASE_STORAGE_BUCKET,
  messagingSenderId: process.env.FIREBASE_MESSAGING_SENDER_ID,
  appId: process.env.FIREBASE_APP_ID,
  measurementId: process.env.FIREBASE_MEASUREMENT_ID,
};

const app = initializeApp(firebaseConfig);
const db = getFirestore(app);

const cityLA = {
  name: "Los Angeles",
  state: "CA",
  country: "USA",
};

const citySF = {
  name: "San Francisco",
  state: "CA",
  country: "USA",
};

/**
 * Create a new collection and add the first document.
 * Method 1: addDoc() - Add a new document with a unique ID generated by Firestore
 * Method 2: setDoc() - Add a new document with a specific ID (preferred)
 */

// // Method 1: Add a new document with a unique ID generated by Firestore - If the document already exists, it will create a new one because the IDs are unique.
// addDoc(collection(db, "cities"), citySF).then((docRef) => {
//   console.log("Document written with ID: ", docRef.id);
// });

// // Method 2: Add a new document with a specific ID - If the ID already exists, it will be overwritten
// setDoc(doc(db, "cities", "LA"), cityLA).then(() => {
//   console.log("Document written with ID: LA");
// });

// Retrieve the Cities collection
const citiesRef = collection(db, "cities");
getDocs(citiesRef)
  .then((querySnapshot) => {
    querySnapshot.forEach((doc) => {
      console.log(`${doc.id} => ${doc.data().name}`);
    });
  })
  .catch((error) => {
    console.error("Error getting documents: ", error);
  });

// Retrieve the LA document based on its ID
const laRef = doc(db, "cities", "LA");
getDoc(laRef)
  .then((docSnap) => {
    if (docSnap.exists()) {
      console.log("Document data:", docSnap.data());
    } else {
      console.log("No such document!");
    }
  })
  .catch((error) => {
    console.error("Error getting document:", error);
  });

// Update the LA document - Add a a new field and merge it with the existing data
setDoc(laRef, { population: 4000000 }, { merge: true })
  .then(() => {
    console.log("Document successfully updated!");
  })
  .catch((error) => {
    console.error("Error updating document:", error);
  });

// Add 2 more cities to the cities collection
const twoCities = [
  {
    name: "New York",
    state: "NY",
    country: "USA",
  },
  {
    name: "London",
    country: "UK",
  },
];

// Use batch writes to add multiple documents
const batchWrites = writeBatch(db);

twoCities.forEach((city) => {
  // Create a new reference for each city
  const newCityRef = doc(citiesRef, city.name);
  // Add the city to the batch
  batchWrites.set(newCityRef, city);
});

// Access London ref and add population field
const londonRef = doc(citiesRef, "London");
batchWrites.update(londonRef, { population: 9000000 });

// Access LA ref and delete the population field
batchWrites.update(laRef, {
  population: null,
});

// Commit the batch
batchWrites
  .commit()
  .then(() => {
    console.log("Batch write successful!");
  })
  .catch((error) => {
    console.error("Error writing batch:", error);
  });

// Change LA to Los Angeles
getDoc(laRef).then((docSnap) => {
  const oldData = docSnap.data();
  const updatedData = { ...oldData, name: "Los Angeles" };
  // Create a new document with the updated data
  setDoc(citiesRef, updatedData).then(() => {
    console.log("Document updated successfully!");
  });
});