Unsubscribing in GraphQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to unsubscribe from a GraphQL subscription.

GraphQL

const unsubscribe = subscriptionClient.[1]();

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

Apublish

Bunsubscribe

Cconnect

Dsubscribe

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'subscribe' instead of 'unsubscribe' will start a subscription, not stop it.

Using 'connect' or 'publish' are unrelated to unsubscribing.

The unsubscribe method stops the subscription and cleans up resources.

2fill in blank

medium

Complete the code to stop receiving updates by calling the correct method on the subscription object.

GraphQL

const subscription = client.subscribe({ query: MY_SUBSCRIPTION });
subscription.[1]();

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

Astart

Bconnect

Clisten

Dunsubscribe

Attempts:

3 left

💡 Hint

Common Mistakes

Calling 'start' or 'listen' will not stop the subscription.

Using 'connect' is unrelated to unsubscribing.

Calling unsubscribe() on the subscription object stops the updates.

3fill in blank

hard

Fix the error in the code to properly unsubscribe from a GraphQL subscription.

GraphQL

const sub = client.subscribe({ query: SUBSCRIPTION_QUERY });
// Incorrect unsubscribe call
sub.[1]();

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

Aunsubscribe

Bsubscribe

Cdisconnect

Dcancel

Attempts:

3 left

💡 Hint

Common Mistakes

Calling 'subscribe' again instead of 'unsubscribe'.

Using 'disconnect' or 'cancel' which are not standard methods.

The correct method to stop a subscription is unsubscribe(). Using subscribe() again or other methods will not stop it.

4fill in blank

hard

Fill both blanks to correctly create and then unsubscribe from a GraphQL subscription.

GraphQL

const subscription = client.[1]({ query: SUBSCRIPTION });
subscription.[2]();

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

Asubscribe

Bunsubscribe

Cconnect

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'connect' or 'start' instead of 'subscribe' to begin.

Using 'connect' or 'start' instead of 'unsubscribe' to stop.

You first call subscribe to start the subscription, then unsubscribe to stop it.

5fill in blank

hard

Fill all three blanks to subscribe, handle data, and then unsubscribe properly.

GraphQL

const subscription = client.[1]({ query: SUBSCRIPTION });
subscription.[2](({ data }) => {
  console.log(data);
});
subscription.[3]();

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

Asubscribe

Cunsubscribe

Dconnect

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'connect' instead of 'subscribe' to start.

Not calling 'unsubscribe' to stop the subscription.

First, call subscribe to start the subscription and provide a callback to handle data. Finally, call unsubscribe to stop the subscription.

Practice

1.

What does calling unsubscribe() on a GraphQL subscription do?

easy

A. It pauses the subscription but keeps the connection alive.

B. It restarts the subscription to receive updates again.

C. It deletes the subscription from the server permanently.

D. It stops receiving live updates from the subscription.

Solution

1. Step 1: Understand the purpose of unsubscribe()

   The unsubscribe() method is designed to stop live updates from a GraphQL subscription.

2. Step 2: Differentiate from other actions

   It does not restart, delete permanently, or pause the subscription; it simply stops updates.

3. Final Answer:

   It stops receiving live updates from the subscription. -> Option D

4. Quick Check:

   Unsubscribe() stops updates = D [OK]

Hint: Remember: unsubscribe() means stop updates completely [OK]

Common Mistakes:

• Thinking unsubscribe() restarts the subscription
• Confusing unsubscribe() with deleting the subscription
• Assuming unsubscribe() only pauses updates

2.

Which of the following is the correct syntax to stop a GraphQL subscription stored in variable sub?

const sub = client.subscribe({ query: MY_SUBSCRIPTION });
// Stop subscription here

easy

A. sub.stop();

B. unsubscribe(sub);

C. sub.unsubscribe();

D. client.unsubscribe(sub);

Solution

1. Step 1: Identify the unsubscribe method on subscription object

   The subscription object returned by client.subscribe() has an unsubscribe() method to stop it.

2. Step 2: Match correct syntax

   Calling sub.unsubscribe(); correctly stops the subscription. Other options are invalid method calls.

3. Final Answer:

   sub.unsubscribe(); -> Option C

4. Quick Check:

   Call unsubscribe() on subscription object = A [OK]

Hint: Use unsubscribe() method on the subscription variable [OK]

Common Mistakes:

• Using unsubscribe() as a standalone function
• Calling stop() instead of unsubscribe()
• Trying to unsubscribe via client object

3.

Given the code below, what will be logged after sub.unsubscribe() is called?

const sub = client.subscribe({ query: MY_SUBSCRIPTION });
sub.subscribe({
  next(data) { console.log('Received:', data); },
  error(err) { console.error('Error:', err); }
});

sub.unsubscribe();

// Later, server sends new data

medium

A. An error will be logged because subscription is closed.

B. No logs will appear after unsubscribe is called.

C. Logs will continue showing 'Received:' with new data.

D. Logs will show 'Received:' once more then stop.

Solution

1. Step 1: Understand unsubscribe effect on subscription callbacks

   Calling unsubscribe() stops the subscription and prevents further next callbacks.

2. Step 2: Predict logging behavior after unsubscribe

   Since subscription is stopped, no new data triggers console.log, so no logs appear after unsubscribe.

3. Final Answer:

   No logs will appear after unsubscribe is called. -> Option B

4. Quick Check:

   Unsubscribe stops callbacks = C [OK]

Hint: After unsubscribe, no more data callbacks occur [OK]

Common Mistakes:

• Expecting data logs after unsubscribe
• Assuming unsubscribe triggers an error
• Thinking one last data event logs after unsubscribe

4.

Identify the error in the code below that prevents unsubscribing correctly:

const subscription = client.subscribe({ query: NEW_MESSAGES });
subscription.next({
  next(data) { console.log(data); }
});

subscription.unsubscribe();

medium

A. Using subscription.next() instead of subscription.subscribe().

B. Calling unsubscribe() before subscribing.

C. Missing error callback in subscription.

D. Not assigning subscription to a variable.

Solution

1. Step 1: Check subscription method usage

   The subscription object uses subscribe() to listen for data, not next().

2. Step 2: Identify correct method to receive data

   Replacing subscription.next() with subscription.subscribe() fixes the issue and allows unsubscribe to work properly.

3. Final Answer:

   Using subscription.next() instead of subscription.subscribe(). -> Option A

4. Quick Check:

   Use subscribe(), not next(), to listen = B [OK]

Hint: Use subscribe() method to listen, not next() [OK]

Common Mistakes:

• Calling next() instead of subscribe()
• Unsubscribing before subscribing
• Ignoring error callback (not critical here)

5.

You have multiple active subscriptions stored in an array subs. How do you efficiently unsubscribe from all of them?

const subs = [sub1, sub2, sub3];
// Your code here

hard

A. subs.forEach(s => s.unsubscribe());

B. subs.unsubscribe();

C. for (let i = 0; i < subs.length; i++) { unsubscribe(subs[i]); }

D. subs.map(s => s.stop());

Solution

1. Step 1: Understand unsubscribing multiple subscriptions

   Each subscription object has an unsubscribe() method to stop it individually.

2. Step 2: Use array iteration to call unsubscribe on each

   Using subs.forEach(s => s.unsubscribe()); calls unsubscribe on all subscriptions efficiently.

3. Final Answer:

   subs.forEach(s => s.unsubscribe()); -> Option A

4. Quick Check:

   Call unsubscribe() on each subscription in array = A [OK]

Hint: Use forEach to unsubscribe all in array [OK]

Common Mistakes:

• Calling unsubscribe() on the array itself
• Using stop() method which does not exist
• Trying to call unsubscribe() without iteration