Cloud Firestore integration in Android Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to get an instance of Firestore.

Android Kotlin

val db = FirebaseFirestore.[1]()

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AgetInstance

Binitialize

Cconnect

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'initialize()' instead of 'getInstance()'.

Trying to create Firestore with 'connect()'.

The correct method to get a Firestore instance is getInstance().

2fill in blank

medium

Complete the code to add a new document to the 'users' collection.

Android Kotlin

db.collection("users").[1](userData)

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Aget

Bupdate

Cadd

Ddelete

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'get()' which only reads data.

Using 'update()' which requires an existing document.

Use add() to add a new document with generated ID to a collection.

3fill in blank

hard

Fix the error in the code to listen for realtime updates on 'messages' collection.

Android Kotlin

db.collection("messages").addSnapshotListener { snapshots, [1] ->
    if (error != null) {
        return@addSnapshotListener
    }
    // process snapshots
}

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Athrowable

Bexception

Cfailure

Derror

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'exception' or 'error' which are not the parameter names here.

Using 'failure' which is not defined.

The listener callback uses throwable to check for problems.

4fill in blank

hard

Fill both blanks to update the 'age' field of a document with ID 'userId' in 'users' collection.

Android Kotlin

db.collection("users").document(userId).[1](mapOf("age" to [2]))

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Aupdate

Bset

C25

D30

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'set()' which replaces the whole document.

Using a wrong age value.

Use update() to change specific fields. The age value here is 25.

5fill in blank

hard

Fill all three blanks to query 'products' collection for items with price greater than 100 and order by price ascending.

Android Kotlin

db.collection("products").whereGreaterThan("[1]", [2]).orderBy("[3]")

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Aprice

B100

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'name' instead of 'price' for filtering or ordering.

Using a wrong number for comparison.

We filter by 'price' greater than 100 and order by 'price'.