Supported data types in Firebase - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set a Firestore document field with a supported data type.

Firebase

docRef.set({"age": [1])

Drag options to blanks, or click blank then click option'

A25

Bundefined

C"twenty-five"

Dfunction() {}

Attempts:

3 left

💡 Hint

Common Mistakes

Using unsupported types like functions or undefined

Using strings when a number is expected

Firestore supports numbers like 25 as valid data types for document fields.

2fill in blank

medium

Complete the code to add a timestamp field using Firestore's supported data types.

Firebase

docRef.set({"createdAt": [1])

Drag options to blanks, or click blank then click option'

Anew Date()

Bfirebase.firestore.Timestamp.now()

C"2024-01-01"

DDate.now()

Attempts:

3 left

💡 Hint

Common Mistakes

Using plain Date objects or strings instead of Firestore Timestamp

Using numeric timestamps directly

Firestore uses firebase.firestore.Timestamp for timestamp fields to ensure proper storage and querying.

3fill in blank

hard

Fix the error in the code to store a supported array type in Firestore.

Firebase

docRef.set({"tags": [1])

Drag options to blanks, or click blank then click option'

A["cloud", "firebase"]

B{"cloud": true, "firebase": true}

Cundefined

Dnew Set(["cloud", "firebase"])

Attempts:

3 left

💡 Hint

Common Mistakes

Using objects or sets instead of arrays

Using undefined or null values

Firestore supports arrays as JavaScript arrays, not as objects or sets.

4fill in blank

hard

Fill both blanks to correctly store a nested map with supported data types in Firestore.

Firebase

docRef.set({"user": {"name": [1], "age": [2])

Drag options to blanks, or click blank then click option'

A"Alice"

B30

Cnull

Dundefined

Attempts:

3 left

💡 Hint

Common Mistakes

Using undefined or null values

Using wrong data types for fields

Firestore supports nested maps with string and number values as shown.

5fill in blank

hard

Fill all three blanks to correctly store different supported Firestore data types in a document.

Firebase

docRef.set({"active": [1], "score": [2], "joined": [3])

Drag options to blanks, or click blank then click option'

Atrue

B85.5

Cfirebase.firestore.Timestamp.now()

D"yes"

Attempts:

3 left

💡 Hint

Common Mistakes

Using strings instead of booleans

Using plain Date objects instead of Firestore Timestamp

Firestore supports booleans, numbers, and timestamps as shown.

Practice

1. Which of the following is NOT a supported data type in Firebase Firestore?

easy

A. String

B. Function

C. Boolean

D. GeoPoint

Solution

1. Step 1: Review Firebase supported data types

   Firebase supports strings, booleans, numbers, arrays, maps, timestamps, and geopoints.

2. Step 2: Identify unsupported type

   Functions are not stored as data types in Firestore; they are part of code logic, not data.

3. Final Answer:

   Function -> Option B

4. Quick Check:

   Functions are not data types in Firestore [OK]

Hint: Remember: Firestore stores data, not code like functions [OK]

Common Mistakes:

• Confusing code functions with data types
• Thinking all JavaScript types are supported
• Assuming Firestore stores executable code

2. Which is the correct way to store a timestamp in Firebase Firestore?

easy

A. Store as a number representing milliseconds since epoch

B. Use a string with date format like '2024-06-01'

C. Use the Firebase Timestamp type

D. Use a boolean true or false

Solution

1. Step 1: Understand Firestore timestamp storage

   Firestore has a special Timestamp type to store date and time accurately.

2. Step 2: Compare options

   Strings and numbers can store dates but lack Firestore's timestamp features; booleans are unrelated.

3. Final Answer:

   Use the Firebase Timestamp type -> Option C

4. Quick Check:

   Timestamp type stores dates best [OK]

Hint: Use Firebase Timestamp for dates, not strings or numbers [OK]

Common Mistakes:

• Storing dates as plain strings
• Using numbers without Timestamp type
• Confusing booleans with dates

3. What will be the data type of the field location after this Firestore document is saved?

const docData = { location: new firebase.firestore.GeoPoint(40.7128, -74.0060) };

medium

A. GeoPoint

B. Array

C. String

D. Map

Solution

1. Step 1: Identify the data type used

   The code uses new firebase.firestore.GeoPoint() which creates a GeoPoint object.

2. Step 2: Understand Firestore storage

   Firestore stores GeoPoint objects as GeoPoint type, representing geographic coordinates.

3. Final Answer:

   GeoPoint -> Option A

4. Quick Check:

   GeoPoint stores latitude and longitude [OK]

Hint: GeoPoint objects store coordinates, not strings or arrays [OK]

Common Mistakes:

• Thinking GeoPoint is stored as string
• Assuming coordinates are arrays
• Confusing GeoPoint with map type

4. You try to save this data in Firestore:

{ name: 'Alice', age: '25' }

But you want age to be a number. What is the error and how to fix it?

medium

A. No error, Firestore converts string to number automatically

B. No error, but age should be stored as boolean true

C. Error: Firestore does not allow strings, use boolean instead

D. Error: age is string, fix by storing age as number 25

Solution

1. Step 1: Check data types in the object

   Age is stored as a string '25', not a number 25.

2. Step 2: Understand Firestore type strictness

   Firestore stores data as given; it does not convert string to number automatically.

3. Final Answer:

   Error: age is string, fix by storing age as number 25 -> Option D

4. Quick Check:

   Store numbers as numbers, not strings [OK]

Hint: Store numbers as numbers, not strings to avoid type errors [OK]

Common Mistakes:

• Assuming Firestore auto-converts types
• Using booleans for numbers
• Ignoring type mismatch warnings

5. You want to store a user's profile with name, age, location (latitude and longitude), and signup date in Firestore. Which data types should you use for location and signupDate fields?

hard

A. location as GeoPoint, signupDate as Timestamp

B. location as Map with lat/lng numbers, signupDate as string

C. location as Array of numbers, signupDate as number (milliseconds)

D. location as string 'lat,lng', signupDate as boolean true

Solution

1. Step 1: Identify best types for location and date

   Firestore provides GeoPoint for geographic coordinates and Timestamp for dates.

2. Step 2: Evaluate options

   Using GeoPoint and Timestamp ensures correct storage, querying, and indexing.

3. Final Answer:

   location as GeoPoint, signupDate as Timestamp -> Option A

4. Quick Check:

   Use GeoPoint and Timestamp for location and dates [OK]

Hint: Use GeoPoint for locations and Timestamp for dates [OK]

Common Mistakes:

• Storing dates as strings
• Using arrays for location
• Confusing booleans with dates