PHP Redis::ttl() Method: Usage and Examples

Returns time-to-live in seconds or sentinel values for missing/nonexpiring keys.

The objective is to understand the behavior and operational limits, not only the method name.

What It Does

Returns time-to-live in seconds or sentinel values for missing/nonexpiring keys.

Syntax and Return Value

Redis::ttl(...)

The return value and exceptional cases depend on the call described here: -1 means the key exists without expiry; -2 means the key does not exist.

Requirements: install and enable the corresponding PHP driver or extension and configure the service before running the examples.

Example 1: Basic Use

Requires the phpredis extension and a running Redis server. Keys use a guide-specific prefix; clean up example keys after experimenting.

<?php
$redis = new Redis();
$redis->connect(getenv('REDIS_HOST') ?: '127.0.0.1', (int) (getenv('REDIS_PORT') ?: 6379), 2.0);
$redis->setex('guide:ttl:1',120,'draft');
echo $redis->ttl('guide:ttl:1');

Example 2: A Second Scenario

Requires the phpredis extension and a running Redis server. Keys use a guide-specific prefix; clean up example keys after experimenting.

<?php
$redis = new Redis();
$redis->connect(getenv('REDIS_HOST') ?: '127.0.0.1', (int) (getenv('REDIS_PORT') ?: 6379), 2.0);
$redis->setex('guide:ttl:2',120,'review');
echo $redis->ttl('guide:ttl:2');

Example 3: Practical Checks

Requires the phpredis extension and a running Redis server. Keys use a guide-specific prefix; clean up example keys after experimenting.

<?php
$redis = new Redis();
$redis->connect(getenv('REDIS_HOST') ?: '127.0.0.1', (int) (getenv('REDIS_PORT') ?: 6379), 2.0);
$redis->setex('guide:ttl:3',120,'published');
echo $redis->ttl('guide:ttl:3');

Important Behavior and Edge Cases

-1 means the key exists without expiry; -2 means the key does not exist.

For production use, also account for error handling, data validation, resource limits and environment-specific driver behavior.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• Returns time-to-live in seconds or sentinel values for missing/nonexpiring keys.
• -1 means the key exists without expiry; -2 means the key does not exist.
• expire assigns TTL; pTTL reports milliseconds.

Choose this API or pattern when its exact semantics match your task, and verify the result against the database driver and runtime used by your application.