CRUD operations

Set Data

This would set data (inserting a document) with an explicit ID.

async function exampleData(db) {

  // Create a reference to the cities collection
  const citiesRef = db.collection('cities');

  await citiesRef.doc('SF').set({ // 'SF' would be the doc's ID
    name: 'San Francisco', state: 'CA', country: 'USA',
    capital: false, population: 860000,
    regions: ['west_coast', 'norcal']
  });
  await citiesRef.doc('LA').set({
    name: 'Los Angeles', state: 'CA', country: 'USA',
    capital: false, population: 3900000,
    regions: ['west_coast', 'socal']
  });
  await citiesRef.doc('DC').set({
    name: 'Washington, D.C.', state: null, country: 'USA',
    capital: true, population: 680000,
    regions: ['east_coast']
  });
  await citiesRef.doc('TOK').set({
    name: 'Tokyo', state: null, country: 'Japan',
    capital: true, population: 9000000,
    regions: ['kanto', 'honshu']
  });
  await citiesRef.doc('BJ').set({
    name: 'Beijing', state: null, country: 'China',
    capital: true, population: 21500000,
    regions: ['jingjinji', 'hebei']
  });

}

This would add a document with an auto-generated ID:

// Add a new document with a generated id.
const res = await db.collection('cities').add({
  name: 'Tokyo',
  country: 'Japan'
});

console.log('Added document with ID: ', res.id);

Read one document by ID

async function getDocument(db) {

  const cityRef = db.collection('cities').doc('SF'); // 'SF' is the doc's ID
  const doc = await cityRef.get();
  if (!doc.exists) {
    console.log('No such document!');
  } else {
    console.log('Document data:', doc.data());
  }

}

Get multiple documents

The query results, stored in the snapshot object, will be iterable.

To get all documents in a collection, the where clause is removed.

async function getMultiple(db) {

  // Create a reference to the cities collection
  const citiesRef = db.collection('cities');
  const snapshot = await citiesRef.where('capital', '==', true).get();
  if (snapshot.empty) {
    console.log('No matching documents.');
    return;
  }  

  snapshot.forEach(doc => {
    console.log(doc.id, '=>', doc.data());
  });

}