# DJANGO Session And Cache

## Session settings
`settings.py:`
```python
SESSION_COOKIE_AGE = 30 * 60              # Session time 30 minutes
SESSION_SAVE_EVERY_REQUEST = True         # Session time resets with every request
SESSION_EXPIRE_AT_BROWSER_CLOSE = False   # Session doesn't quit when browser clos
```
:::warning
Session is stored per default in database - so a *SESSION_SAVE_EVERY_REQUEST* does a lot of additional database updates. Could be changed by using a cache like Redis
:::

## Using Cache
### Installation
```bash
sudo apt redis-server
sudo systemctl enable --now redis-server
redis-cli ping
```
in python env (.venv):
```bash
pip install redis
```

### Configuration
`settings.py:`
```python
CACHES = {
    "default": {
        "BACKEND": "django.core.cache.backends.dummy.DummyCache",
    },



    "sessions": {
        "BACKEND": "django.core.cache.backends.redis.RedisCache",
        "LOCATION": "redis://127.0.0.1:6379/1",
    },
}

SESSION_ENGINE = "django.contrib.sessions.backends.cache"
SESSION_CACHE_ALIAS = "sessions"
```
:::warning
Because sessions are now only in the cache - a restart of the RedisCache would delete all sessions and everyone would get logged out immediately.
:::

### Using Cache and Database
```python
SESSION_ENGINE = "django.contrib.sessions.backends.cached_db"
```
- would write both to database and cache (so no help for the database)
- only the reads would be buffered by the cache