Inserts one or more items at the head of a list and returns the resulting length.
The objective is to understand the behavior and operational limits, not only the method name.
What It Does
Inserts one or more items at the head of a list and returns the resulting length.
Syntax and Return Value
Redis::lPush(...)The return value and exceptional cases depend on the call described here: Pushing several values affects their left-to-right order in the list.
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);
$redis->lPush('guide:lpush:1',"first",'draft');
echo json_encode($redis->lRange('guide:lpush:1',0,-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);
$redis->lPush('guide:lpush:2',"first",'review');
echo json_encode($redis->lRange('guide:lpush:2',0,-1));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);
$redis->lPush('guide:lpush:3',"first",'published');
echo json_encode($redis->lRange('guide:lpush:3',0,-1));Important Behavior and Edge Cases
Pushing several values affects their left-to-right order in the list.
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::lPush | Inserts one or more items at the head of a list and returns the resulting length. |
| Related API / pattern | rPush appends at the tail of the list. |
Common Beginner Mistakes
| Mistake | Correct approach |
|---|---|
| Assuming the happy path covers edge cases | Pushing several values affects their left-to-right order in the list. |
| Using a related API interchangeably | rPush appends at the tail of the list. |
Key Takeaways
- Inserts one or more items at the head of a list and returns the resulting length.
- Pushing several values affects their left-to-right order in the list.
- rPush appends at the tail of the list.
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.