Stores a string key with an expiration measured in seconds.
The objective is to understand the behavior and operational limits, not only the method name.
What It Does
Stores a string key with an expiration measured in seconds.
Syntax and Return Value
Redis::setex(...)The return value and exceptional cases depend on the call described here: TTL must be positive; the key expires automatically without a separate expire call.
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:setex:1',90,'draft');
echo $redis->ttl('guide:setex: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:setex:2',90,'review');
echo $redis->ttl('guide:setex: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:setex:3',90,'published');
echo $redis->ttl('guide:setex:3');Important Behavior and Edge Cases
TTL must be positive; the key expires automatically without a separate expire call.
For production use, also account for error handling, data validation, resource limits and environment-specific driver behavior.
Comparison with Related Approaches
| Approach | Important distinction |
|---|---|
| Redis::setex | Stores a string key with an expiration measured in seconds. |
| Related API / pattern | set with an EX option is the modern generalized alternative. |
Common Beginner Mistakes
| Mistake | Correct approach |
|---|---|
| Assuming the happy path covers edge cases | TTL must be positive; the key expires automatically without a separate expire call. |
| Using a related API interchangeably | set with an EX option is the modern generalized alternative. |
Key Takeaways
- Stores a string key with an expiration measured in seconds.
- TTL must be positive; the key expires automatically without a separate expire call.
- set with an EX option is the modern generalized alternative.
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.