Cloud Firestore Database

What is Cloud Firestore?

How Data is Organized

Firestore vs. Realtime Database

Accessing Firestore in Flutter

import 'package:cloud_firestore/cloud_firestore.dart';
// Ensure Firebase is initialized in your main() or similar
// For example: await Firebase.initializeApp();

void main() {
  FirebaseFirestore db = FirebaseFirestore.instance;
  print("Firestore instance obtained!");
  // You would typically use this 'db' instance
  // within your Flutter widgets.
}

Storing New Documents

import 'package:cloud_firestore/cloud_firestore.dart';
// Assume Firebase.initializeApp() is done.

void main() async {
  FirebaseFirestore db = FirebaseFirestore.instance;

  // Using .add() - Firestore generates a document ID
  DocumentReference docRef = await db.collection("users").add({
    "name": "Alice",
    "email": "alice@example.com",
    "age": 30,
    "isActive": true
  });
  print("Document added with ID: ${docRef.id}");

  // Using .set() - you provide the document ID
  await db.collection("cities").doc("LA").set({
    "name": "Los Angeles",
    "state": "CA",
    "country": "USA"
  });
  print("City 'LA' added.");
}

Fetching Data Once

import 'package:cloud_firestore/cloud_firestore.dart';
// Assume Firebase.initializeApp() is done.

void main() async {
  FirebaseFirestore db = FirebaseFirestore.instance;

  // Replace 'some_doc_id' with an actual ID from your Firestore
  DocumentSnapshot doc = await db.collection("users").doc("some_doc_id").get();

  if (doc.exists) {
    print("Document data: ${doc.data()}");
    print("User name: ${doc.get('name')}");
  } else {
    print("No such document!");
  }
}

Modifying Existing Documents

import 'package:cloud_firestore/cloud_firestore.dart';
// Assume Firebase.initializeApp() is done.

void main() async {
  FirebaseFirestore db = FirebaseFirestore.instance;

  // Replace 'some_doc_id' with an actual ID
  String docIdToUpdate = "some_doc_id";

  await db.collection("users").doc(docIdToUpdate).update({
    "age": 31,
    "city": "New York" // Add a new field
  });
  print("Document updated successfully!");

  // You can also update nested fields using dot notation
  // await db.collection("users").doc(docIdToUpdate).update({
  //   "address.street": "Main St"
  // });
}

Removing Documents and Fields

import 'package:cloud_firestore/cloud_firestore.dart';
// Assume Firebase.initializeApp() is done.

void main() async {
  FirebaseFirestore db = FirebaseFirestore.instance;

  // Replace with an actual document ID you wish to delete
  String docIdToDelete = "some_other_doc_id";

  // Delete a specific field from a document
  await db.collection("users").doc("some_doc_id").update({
    "isActive": FieldValue.delete()
  });
  print("Field 'isActive' deleted from document 'some_doc_id'.");

  // Delete an entire document
  await db.collection("users").doc(docIdToDelete).delete();
  print("Document '${docIdToDelete}' deleted.");
}

Real-time Data Updates

import 'package:cloud_firestore/cloud_firestore.dart';
// Assume Firebase.initializeApp() is done.

void main() {
  FirebaseFirestore db = FirebaseFirestore.instance;

  // Listen to a single document
  db.collection("users").doc("some_doc_id").snapshots().listen((snapshot) {
    if (snapshot.exists) {
      print("Real-time update for doc: ${snapshot.data()}");
    } else {
      print("Document no longer exists.");
    }
  });

  // Listen to a whole collection
  db.collection("users").snapshots().listen((snapshot) {
    print("Real-time update for collection. Total docs: ${snapshot.docs.length}");
    for (var doc in snapshot.docs) {
      print("  - ${doc.id}: ${doc.data()['name']}");
    }
  });

  print("Listeners set up. App will now receive real-time updates.");
  // In a real Flutter app, this would be part of a StatefulWidget's initState
  // and listeners would be cancelled in dispose().
}

Advanced Data Queries

Firestore Operations Check

Firestore Summary