Firestore document model in GCP - Mini Project: Build & Apply

Firestore Document Model

📖 Scenario: You are building a simple app to store user profiles in Google Firestore. Each user has a unique ID, a name, and an email address. You want to create the Firestore document model to represent these users.

🎯 Goal: Create a Firestore document model by defining a dictionary that represents a user profile, add a configuration for the collection name, write the code to add the user document to Firestore, and complete the Firestore client initialization.

📋 What You'll Learn

Create a dictionary called user_profile with keys id, name, and email and exact values "user123", "Alice Smith", and "[e-mail]" respectively.

Create a variable called collection_name and set it to "users".

Write code to add the user_profile dictionary as a document to the Firestore collection named collection_name using the id as the document ID.

Initialize the Firestore client by importing the necessary module and creating a client instance called db.

💡 Why This Matters

🌍 Real World

Firestore is a popular NoSQL database used in many cloud applications to store and sync data in real time. Modeling documents correctly is essential for efficient data storage and retrieval.

💼 Career

Understanding Firestore document models and how to interact with Firestore using client libraries is a key skill for cloud developers and engineers working with Google Cloud Platform.

1

Create the user profile dictionary

Create a dictionary called user_profile with these exact entries: 'id': 'user123', 'name': 'Alice Smith', and 'email': '[e-mail]'.

GCP

# Create the user_profile dictionary with id, name, and email
# Your code here

Hint

Use curly braces to create a dictionary and separate keys and values with colons.

2

Set the Firestore collection name

Create a variable called collection_name and set it to the string 'users'.

GCP

user_profile = {'id': 'user123', 'name': 'Alice Smith', 'email': '[e-mail]'}
# Create the collection_name variable and set it to 'users'
# Your code here

Hint

Assign the string 'users' to the variable collection_name.

3

Add the user document to Firestore

Write code to add the user_profile dictionary as a document to the Firestore collection named collection_name using the id field as the document ID. Use db.collection(collection_name).document(user_profile['id']).set(user_profile).

GCP

user_profile = {'id': 'user123', 'name': 'Alice Smith', 'email': '[e-mail]'}
collection_name = 'users'
# Add the user_profile document to Firestore using the id as document ID
# Your code here

Hint

Use the Firestore client db to access the collection and set the document.

4

Initialize the Firestore client

Import firestore from google.cloud and create a Firestore client instance called db using firestore.Client().

GCP

# Import firestore and create the client instance db
# Your code here
user_profile = {'id': 'user123', 'name': 'Alice Smith', 'email': '[e-mail]'}
collection_name = 'users'
db.collection(collection_name).document(user_profile['id']).set(user_profile)

Hint

Use the import statement and create the client before using it.

Practice

1. What is the basic unit of data storage in Firestore?

easy

A. A table

B. A document

C. A bucket

D. A file

Solution

1. Step 1: Understand Firestore data structure

   Firestore organizes data into collections and documents, not tables or files.

2. Step 2: Identify the smallest data unit

   The smallest unit is a document, which holds fields and values.

3. Final Answer:

   A document -> Option B

4. Quick Check:

   Firestore stores data as documents [OK]

Hint: Remember: Firestore uses documents, not tables or files [OK]

Common Mistakes:

• Confusing documents with tables from SQL databases
• Thinking Firestore stores files like Cloud Storage
• Assuming buckets are data units in Firestore

2. Which of the following is the correct way to represent a Firestore document field in JSON-like syntax?

easy

A. "name": "Alice"

B. "name" = "Alice"

C. name: Alice

D. 'name' -> 'Alice'

Solution

1. Step 1: Recall JSON field syntax

   JSON uses double quotes for keys and string values, separated by a colon.

2. Step 2: Match Firestore document field style

   Firestore documents resemble JSON, so the correct syntax is "key": "value".

3. Final Answer:

   "name": "Alice" -> Option A

4. Quick Check:

   Firestore fields use JSON syntax [OK]

Hint: Use colon and double quotes for Firestore fields [OK]

Common Mistakes:

• Using equals sign instead of colon
• Omitting quotes around keys or values
• Using arrow notation which is invalid

3. Given a Firestore collection 'users' with documents having fields {"age": 30, "active": true}, what will the query return if you filter for documents where active == false?

medium

A. All documents with active false

B. All documents regardless of active field

C. Error due to invalid filter

D. No documents

Solution

1. Step 1: Understand the data and filter condition

   Documents have "active": true, but the query filters for active == false.

2. Step 2: Evaluate query result

   No documents match active == false, so the query returns no results.

3. Final Answer:

   No documents -> Option D

4. Quick Check:

   Filter matches no documents [OK]

Hint: Filter matches only exact values; no match means empty result [OK]

Common Mistakes:

• Assuming query returns all documents
• Expecting an error for valid filter
• Confusing true and false values

4. You try to add a document with this data: {name: "Bob", age: "twenty"}. What is the likely issue?

medium

A. Firestore requires age to be a number, not a string

B. No issue, document will be added

C. Field names must be in quotes

D. Document ID is missing

Solution

1. Step 1: Check field name syntax

   Firestore expects field names as strings in JSON, so keys must be quoted.

2. Step 2: Analyze the given data

   Keys are unquoted (name, age), which is invalid JSON syntax for Firestore.

3. Final Answer:

   Field names must be in quotes -> Option C

4. Quick Check:

   Field names need quotes in Firestore JSON [OK]

Hint: Always quote field names in Firestore documents [OK]

Common Mistakes:

• Thinking Firestore auto-corrects missing quotes
• Assuming string values for numbers cause errors
• Believing document ID is mandatory in data

5. You want to model a blog app in Firestore. Each blog post has multiple comments. Which is the best Firestore document model to organize this data?

hard

A. Create a 'posts' collection with documents for each post, and a subcollection 'comments' inside each post document

B. Store all comments as an array field inside each blog post document

C. Create a single collection 'comments' with a field referencing the post ID

D. Store all posts and comments in one flat collection

Solution

1. Step 1: Consider Firestore best practices for related data

   Large or growing lists like comments should be in subcollections, not arrays, for scalability.

2. Step 2: Evaluate options for organizing posts and comments

   Using a 'posts' collection with 'comments' subcollections keeps data organized and efficient.

3. Final Answer:

   Create a 'posts' collection with documents for each post, and a subcollection 'comments' inside each post document -> Option A

4. Quick Check:

   Use subcollections for related many items [OK]

Hint: Use subcollections for many related items, not arrays [OK]

Common Mistakes:

• Putting all comments in one array causing size limits
• Using a flat collection losing post-comment grouping
• Referencing post ID without subcollections complicates queries