Firestore Database: Cheat Sheet (Python)

The quickest way to get started with Google’s Firestore Database using Python.

First, authentication. At the top-left, click on the settings icon (Gear wheel) near “Project Overview”. Click on the top option -> “Project Settings”. Click on “Service accounts”, select python and click on “Generate new private key”. This will trigger a json file to be downloaded. In my example, I call it “secret.json”.

SAVE the file and remember its path, it’s essential in order to authenticate with Firestore.

From now on, I will write as little as possible and code as much as possible, so this will be a cheat sheet and not documentation.

Authentication

Write it only once in code. There is no good reason to reconnect to database with each request. Google’s documentation.

import firebase_admin
from firebase_admin import credentials
from firebase_admin import firestore
from google.cloud.firestore_v1.base_query import FieldFilter, Or # for later

# Certification
cred = credentials.Certificate("secret.json") # secret.json = Private key
firebase_admin.initialize_app(cred)
db = firestore.client() # Database reference

Read / Query / Filter Data

Reading data from Firestore database. Google’s Documentation.

col = db.collection("users") # Make sure this collection is in your database

# Get all the docs in a collection
docs = col.stream()
for doc in docs:
  document_id = doc.id
  document_as_a_dict = doc.to_dict()
  name_field_value_example = doc.to_dict()['name']

# Search for a single document in a collection
query = col.where(filter=FieldFilter("name","==","Ilan"))
docs = query.stream()
for doc in docs:
  print(doc.id, '->', doc.to_dict())

# Optional: Limit amount of results.
# Better to limit because too much reads per day will be charged
query = col.where(filter=FieldFilter("age","==","24"))
limited_query = query.limit(5)
docs = limited_query.stream()
for doc in docs:
  print(doc.id, '->', doc.to_dict())

# Chain two statements with AND

query = col.where(
filter=FieldFilter("age","==","24")).where(
filter=FieldFilter("name","==","Ilan"))
docs = query.stream()
for doc in docs:
  print(doc.id, '->', doc.to_dict())

# Chain two statements with OR

filter_1 = FieldFilter("age",">","24")
filter_2 = FieldFilter("name","==","Ilan")
or_filter = Or(filters=[filter_1, filter_2])

docs = col.where(filter=or_filter).stream()
for doc in docs:
  print(doc.id)

# Filter a query by searching inside field array

query = col.where(filter=FieldFilter("family_members","array_contains","Josh"))
docs = query.stream()
for doc in docs:
  print(doc.id, '->', doc.to_dict())

Reading: Query Operators

As written in firebase docs:

The where() method takes three parameters: a field to filter on, a comparison operator, and a value.

• < 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

Update Data / Delete a Document’s Field

Update document’s field values with new values, Delete document’s fields, Increment document’s field, Append (Add) to a document’s array field. Google’s documentation.

col = db.collection("users") # Make sure this collection is in your database

# First find the data we want to update

query = col.where(filter=FieldFilter("name","==","Ilan"))
doc = query.get()[0] # get is another way of reading, just like stream()

# Update it

col.document(doc.id).update({
  "name": "Daniel",
  "age": 20,
   
})

# Delete a field

col.document(doc.id).update({
  "height": firestore.DELETE_FIELD,
})

# Increment a number field

col.document(doc.id).update({
  "age": firestore.Increment(1),
})

# Append to an array, using Union

col.document(doc.id).update({
  "family_members": firestore.ArrayUnion(["John", "Josh"]),
})

Write Data

Write new data to firebase. Google’s documentation.

col = db.collection("users") # Make sure this collection is in your database

# Add a new document with random-generated id
# Random id example: 02CWbZ9ZukSiHXmYDVFb

col.document().set({
  'name': 'Ilan Yashuk',
  'age': 20,
  'height': 170,
  'family_members': ['Jack', 'Daniel']
})

# Add a new document with custom id

col.document("some_id").set{
  # ...
})