Notification messages vs data messages in Firebase - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to send a notification message with a title.

Firebase

const message = { notification: { title: '[1]' } };

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

AHello World

B123

Ctrue

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Using a number or boolean instead of a string for the title.

Leaving the title empty or null.

The title field in a notification message must be a string, like 'Hello World'.

2fill in blank

medium

Complete the code to send a data message with a key-value pair.

Firebase

const message = { data: { [1]: '12345' } };

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

Abody

Bnotification

CorderId

Dtitle

Attempts:

3 left

💡 Hint

Common Mistakes

Using notification keys inside data messages.

Using reserved keys like 'notification' inside data.

Data messages use custom keys like orderId to send data.

3fill in blank

hard

Fix the error in the message object to correctly send a notification with data.

Firebase

const message = { notification: { title: 'Sale' }, [1]: { discount: '20%' } };

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

Anotification

Bdata

Cpayload

Dmessage

Attempts:

3 left

💡 Hint

Common Mistakes

Repeating 'notification' instead of using 'data'.

Using incorrect field names like 'payload' or 'message'.

The data field is used to send custom key-value pairs alongside notification.

4fill in blank

hard

Fill both blanks to create a message with notification title and data key.

Firebase

const message = { [1]: { title: 'Update' }, [2]: { version: '1.2.3' } };

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

Anotification

Bpayload

Cdata

Dmessage

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping 'notification' and 'data' fields.

Using incorrect field names like 'payload' or 'message'.

The notification field holds the visible message, and data holds extra info.

5fill in blank

hard

Fill all three blanks to send a notification with title, body, and data key.

Firebase

const message = { [1]: { title: 'Alert', [2]: 'Check your app' }, [3]: { alertId: '789' } };

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

Anotification

Bbody

Cdata

Dpayload

Attempts:

3 left

💡 Hint

Common Mistakes

Putting 'body' as a separate top-level field.

Using 'payload' instead of 'data'.

The notification field contains title and body. The data field holds extra info.

Practice

1. What is the main difference between notification messages and data messages in Firebase Cloud Messaging?

easy

A. Notification messages send silent info, data messages automatically show alerts.

B. Both types always show alerts to users.

C. Notification messages automatically show alerts, data messages send silent info.

D. Data messages cannot send any information.

Solution

1. Step 1: Understand notification messages

   Notification messages are designed to automatically display alerts or notifications to the user without extra coding.

2. Step 2: Understand data messages

   Data messages send information silently to the app, which then decides how to handle or display it.

3. Final Answer:

   Notification messages automatically show alerts, data messages send silent info. -> Option C

4. Quick Check:

   Notification = alert, Data = silent info [OK]

Hint: Notification = alert shown; data = silent info sent [OK]

Common Mistakes:

• Confusing which message type shows alerts automatically
• Thinking data messages always show notifications
• Believing notification messages send silent data only

2. Which of the following is the correct JSON structure for sending a notification message with Firebase Cloud Messaging?

easy

A. { "message": { "alert": "Hello World" } }

B. { "data": { "title": "Hello", "body": "World" } }

C. { "notify": { "title": "Hello", "body": "World" } }

D. { "notification": { "title": "Hello", "body": "World" } }

Solution

1. Step 1: Identify notification message format

   Notification messages use the "notification" key with "title" and "body" fields to show alerts.

2. Step 2: Check other options for correctness

   { "data": { "title": "Hello", "body": "World" } } uses "data" which is for data messages, not notification messages. Options A and D use invalid keys.

3. Final Answer:

   { "notification": { "title": "Hello", "body": "World" } } -> Option D

4. Quick Check:

   Notification key with title/body = correct [OK]

Hint: Notification messages use "notification" key with title and body [OK]

Common Mistakes:

• Using "data" key instead of "notification" for alerts
• Using incorrect keys like "message" or "notify"
• Missing required title or body fields

3. Given this Firebase message payload sent to an Android app:

{
  "notification": { "title": "Sale", "body": "50% off!" },
  "data": { "productId": "12345" }
}

What will happen when the app receives this message?

medium

A. The message will cause an error and not be delivered.

B. The app shows a notification with title and body, and data is available for app logic.

C. The app shows only the data as a notification, ignoring title and body.

D. The app only receives silent data, no notification is shown.

Solution

1. Step 1: Analyze notification part

   The "notification" key causes the system to show a notification with the given title and body automatically.

2. Step 2: Analyze data part

   The "data" key sends extra info silently, which the app can use for logic like opening a product page.

3. Final Answer:

   The app shows a notification with title and body, and data is available for app logic. -> Option B

4. Quick Check:

   Notification shows alert + data sent silently [OK]

Hint: Notification key shows alert; data key sends silent info [OK]

Common Mistakes:

• Thinking data messages show notifications automatically
• Believing notification messages ignore data payload
• Assuming message causes error due to combined keys

4. You sent a data message with this payload:

{ "data": { "score": "100" } }

But the app does not receive it when in background. What is the likely cause?

medium

A. Data messages require app code to handle them; no notification shown automatically.

B. Data messages always show notifications automatically, so this is impossible.

C. You must include a "notification" key for data messages to work.

D. Firebase does not support data messages on Android.

Solution

1. Step 1: Understand data message behavior

   Data messages are silent and require the app's code to process them; if the app is in background, it may not receive them unless handled properly.

2. Step 2: Check other options

   Data messages always show notifications automatically, so this is impossible. is false because data messages do not show notifications automatically. You must include a "notification" key for data messages to work. is incorrect; notification key is not required for data messages. Firebase does not support data messages on Android. is false; Firebase supports data messages on Android.

3. Final Answer:

   Data messages require app code to handle them; no notification shown automatically. -> Option A

4. Quick Check:

   Data messages need app handling [OK]

Hint: Data messages need app code; no auto notification [OK]

Common Mistakes:

• Expecting data messages to show notifications automatically
• Adding notification key unnecessarily
• Believing Firebase lacks data message support

5. You want to send a message that both shows a notification alert and passes extra data to the app for custom handling. Which Firebase message payload is best?

hard

A. { "notification": { "title": "Update", "body": "New version available" }, "data": { "version": "2.0" } }

B. { "data": { "title": "Update", "body": "New version available", "version": "2.0" } }

C. { "notification": { "title": "Update" } }

D. { "message": { "alert": "Update", "info": "2.0" } }

Solution

1. Step 1: Identify combined message structure

   To show a notification and send extra data, the payload must include both "notification" and "data" keys.

2. Step 2: Evaluate options

   { "notification": { "title": "Update", "body": "New version available" }, "data": { "version": "2.0" } } correctly combines notification alert and data. { "data": { "title": "Update", "body": "New version available", "version": "2.0" } } sends all as data, so no automatic alert. { "notification": { "title": "Update" } } lacks data for extra info. { "message": { "alert": "Update", "info": "2.0" } } uses invalid keys.

3. Final Answer:

   { "notification": { "title": "Update", "body": "New version available" }, "data": { "version": "2.0" } } -> Option A

4. Quick Check:

   Combine notification + data keys for alert + info [OK]

Hint: Use both notification and data keys to combine alert and info [OK]

Common Mistakes:

• Sending all info as data without notification key
• Missing data key for extra info
• Using invalid keys like "message" or "alert"