What is Firestore?

Learn the collection and document model with Firestore.

What is Firestore?

Firestore is Firebase's NoSQL cloud database; it stores data in a collection and document hierarchy. You access the singleton via FirebaseFirestore.instance. Collections hold documents, and documents hold key-value fields.

final db = FirebaseFirestore.instance;
final ref = db.collection('users').doc('u1');

Real-time synchronization means all clients update instantly when data changes.

Collection and document hierarchy

Data is organized as collection > document > field. A collection contains many documents; each document has a unique id. Collections hold documents, and documents hold fields or subcollections.

db.collection('users')
  .doc('u1')
  .get();

Exercise Create a document reference

Get db via FirebaseFirestore.instance. Create a document reference with id 'u1' in the 'users' collection and print ref.id.

Show example solution

class DocumentReference {
  final String id;
  DocumentReference(this.id);
}

class CollectionReference {
  final String name;
  CollectionReference(this.name);
  DocumentReference doc(String id) => DocumentReference(id);
}

class FirebaseFirestore {
  static final FirebaseFirestore instance = FirebaseFirestore._();
  FirebaseFirestore._();
  CollectionReference collection(String name) => CollectionReference(name);
}

void main() {
  final db = FirebaseFirestore.instance;
  final ref = db.collection('users').doc('u1');
  print(ref.id);
}

Test yourself

What does a document represent in Firestore?
- A single data object holding key-value fields
- Only a title text
- A user password
- The name of a SQL table
Show answer

A single data object holding key-value fields — A document is a single data object holding key-value fields; it lives inside a collection.

Get a collection reference

final col = db.____('users');

Show answer

final col = db.collection('users');

Firestore parts

FirebaseFirestore.instance

Singleton instance
collection

A set of documents
doc

A single document reference
NoSQL

Data model

Next lesson: Add data

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