Node Redis: Getting Default TTL (Detailed Guide w/ Code Examples)

Use Case(s)

Getting the default Time To Live (TTL) in Redis using Node.js can be useful when managing data persistence. Redis doesn't have a built-in command to fetch the default TTL, but it's typically set at the application level.

Code Examples

// Require the redis package
const redis = require('redis');

// Create a client and connect to redis
const client = redis.createClient();

// Set a key with a value and expiry
client.set('myKey', 'myValue', 'EX', 10, redis.print);

// Get the TTL for that key
client.ttl('myKey', function(err, reply) {
    console.log(reply);
});

In this example, we're setting a key-value pair in Redis with an expiration time of 10 seconds. We then retrieve the TTL of the key to ensure it's been set correctly.

Best Practices

• Always handle errors coming from your Redis client.
• Use meaningful and consistent key names for easier debugging and maintenance.

Common Mistakes

• Not handling Redis connection failures or other Redis-related exceptions.
• Trying to get the TTL of a non-expiring key or a key that doesn't exist.

FAQs

Q: What happens if I try to get the TTL of a key that doesn't exist?

A: Redis will return -2 indicating that the key does not exist.

Q: What if the key exists but has no associated expire?

A: Redis will return -1 indicating that the key exists but has no associated expire.

Q: Can I change the TTL of a key after setting it?

A: Yes, you can use the EXPIRE command to modify the TTL of an existing key.