Real-time notification pattern in Redis - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to publish a message to a Redis channel named 'alerts'.

Redis

redis_client.publish('alerts', [1])

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

A'New alert!'

Balerts

Cpublish

D'alerts'

Attempts:

3 left

💡 Hint

Common Mistakes

Using the channel name as the message instead of a string message.

Forgetting to put quotes around the message.

The publish method requires the channel name and the message. The message here is a string 'New alert!'.

2fill in blank

medium

Complete the code to subscribe to the Redis channel 'alerts' using a Redis client.

Redis

redis_client.subscribe([1])

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

Aalerts

B'alerts'

C'messages'

D'subscribe'

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the channel name without quotes.

Using the wrong channel name.

To listen for messages, you subscribe to the channel named 'alerts' as a string.

3fill in blank

hard

Fix the error in the code to correctly handle incoming messages from the 'alerts' channel.

Redis

redis_client.on('message', function(channel, [1]) {
  console.log('Received:', [1])
});

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

Amsg

Bmessage

Cdata

Dalert

Attempts:

3 left

💡 Hint

Common Mistakes

Using a parameter name that does not match inside the function.

Confusing the channel name with the message parameter.

The callback function receives the channel and the message as parameters. 'msg' is a common name for the message parameter.

4fill in blank

hard

Fill both blanks to publish a JSON string notification with a type and content to the 'notifications' channel.

Redis

const notification = JSON.stringify({ type: [1], content: [2] });
redis_client.publish('notifications', notification);

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

A'info'

B'Hello, user!'

C'alert'

D'Welcome message'

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting quotes around string values.

Mixing up type and content values.

The notification object needs a type and content as strings. 'info' and 'Hello, user!' are valid values.

5fill in blank

hard

Fill all three blanks to subscribe to the 'notifications' channel and log parsed JSON messages with type and content.

Redis

redis_client.subscribe([1]);
redis_client.on('message', (channel, [2]) => {
  const data = JSON.parse([3]);
  console.log(`Type: ${data.type}, Content: ${data.content}`);
});

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

A'notifications'

Bmsg

Cmessage

D'alerts'

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong channel name in subscribe.

Parsing the wrong variable inside the callback.

Subscribe to 'notifications' channel, use 'msg' as the message parameter, and parse 'msg' to get the JSON data.