# Redis

## Introduction

The Redis Extension provides application caching and key/value store support via Redis.

Documentation References:

* [Caching](https://docs.builtoncement.com/core-foundation/caching)

API References:

* [Cement Redis Extension](https://cement.readthedocs.io/en/3.0/api/ext/ext_redis/)
* [Redis Library](https://redislabs.com/lp/python-redis/)

## Requirements

* Redis

{% hint style="info" %}
Cement 3.0.8+:

`pip install redis`
{% endhint %}

{% hint style="warning" %}
Applications using Cement <3.0.8 should continue to include `redis` in their dependencies.
{% endhint %}

## Configuration

This extension honors the following config settings under a `[cache.redis]` section in any configuration file:

| **Setting**      | **Description**                                                                           |
| ---------------- | ----------------------------------------------------------------------------------------- |
| **expire\_time** | The default time in seconds to expire items in the cache.  Default: `0` (does not expire) |
| **host**         | Redis server ip address or hostname                                                       |
| **port**         | Redis server port                                                                         |
| **db**           | Redis server database id/namespace                                                        |

## Usage

{% tabs %}
{% tab title="Example: Using Redis Cache Handler" %}
{% code title="myapp.py" %}

```python
from cement import App, init_defaults

CONFIG = init_defaults('myapp', 'cache.redis')
CONFIG['cache.redis']['expire_time'] = 300 # seconds
CONFIG['cache.redis']['host'] = '127.0.0.1'
CONFIG['cache.redis']['port'] = 6379
CONFIG['cache.redis']['db'] = 0

class MyApp(App):
    class Meta:
        label = 'myapp'
        config_defaults = CONFIG
        extensions = ['redis']
        cache_handler = 'redis'

with MyApp() as app:
    # Run the app
    app.run()

    # Set a cached value
    app.cache.set('my_key', 'my value')

    # Get a cached value
    app.cache.get('my_key')

    # Delete a cached value
    app.cache.delete('my_key')

    # Delete the entire cache
    app.cache.purge()
```

{% endcode %}

{% code title="\~/.myapp.conf" %}

```
[myapp]

# set the cache handler to use
cache_handler = redis


[cache.redis]

# time in seconds that an item in the cache will expire
expire_time = 300

# Redis server
host = 127.0.0.1

# Redis port
port = 6379

# Redis database number
db = 0
```

{% endcode %}
{% endtab %}
{% endtabs %}