add timezone example

mattmakai · mattmakai · commit cc5af4bfb394 · 2019-06-21T10:59:23.000-04:00
diff --git a/content/pages/examples/django/django-utils-timezone.markdown b/content/pages/examples/django/django-utils-timezone.markdown
@@ -151,3 +151,124 @@ class Migration(migrations.Migration):
             },
         ),
 ```
+
+
+## Example 3 from django-easy-timezones
+[django-easy-timezones](https://github.com/Miserlou/django-easy-timezones)
+([project website](https://www.gun.io/blog/django-easy-timezones))
+is a [Django](/django.html) 
+[middleware](https://docs.djangoproject.com/en/2.2/topics/http/middleware/)
+[code library](https://pypi.org/project/django-easy-timezones/)
+to simplify handling time data in your applications using
+users' geolocation data.
+
+[**django-easy-timezones/easy_timezones/middleware.py**](https://github.com/Miserlou/django-easy-timezones/blob/master/easy_timezones/middleware.py)
+
+```python
+import django
+from django.conf import settings
+from django.contrib.auth import get_user_model
+from django.core.exceptions import ImproperlyConfigured
+~~from django.utils import timezone
+import pytz
+import pygeoip
+import os
+
+from .signals import detected_timezone
+from .utils import get_ip_address_from_request, is_valid_ip, is_local_ip
+
+
+db_loaded = False
+db = None
+db_v6 = None
+
+def load_db_settings():
+    GEOIP_DATABASE = getattr(settings, 'GEOIP_DATABASE', 'GeoLiteCity.dat')
+
+    if not GEOIP_DATABASE:
+        raise ImproperlyConfigured("GEOIP_DATABASE setting has not been " + \
+                                   "properly defined.")
+
+    if not os.path.exists(GEOIP_DATABASE):
+        raise ImproperlyConfigured("GEOIP_DATABASE setting is defined, " + \
+                                   "but file does not exist.")
+
+    GEOIPV6_DATABASE = getattr(settings, 'GEOIPV6_DATABASE', 
+                               'GeoLiteCityv6.dat')
+
+    if not GEOIPV6_DATABASE:
+        raise ImproperlyConfigured("GEOIPV6_DATABASE setting has not " + \
+                                   "been properly defined.")
+
+    if not os.path.exists(GEOIPV6_DATABASE):
+        raise ImproperlyConfigured("GEOIPV6_DATABASE setting is " + \
+                                   "defined, but file does not exist.")
+
+    return (GEOIP_DATABASE, GEOIPV6_DATABASE)
+
+load_db_settings()
+
+def load_db():
+
+    GEOIP_DATABASE, GEOIPV6_DATABASE = load_db_settings()
+
+    global db
+    db = pygeoip.GeoIP(GEOIP_DATABASE, pygeoip.MEMORY_CACHE)
+
+    global db_v6
+    db_v6 = pygeoip.GeoIP(GEOIPV6_DATABASE, pygeoip.MEMORY_CACHE)
+
+    global db_loaded
+    db_loaded = True
+
+
+if django.VERSION >= (1, 10):
+    from django.utils.deprecation import MiddlewareMixin
+    middleware_base_class = MiddlewareMixin
+else:
+    middleware_base_class = object
+
+
+class EasyTimezoneMiddleware(middleware_base_class):
+    def process_request(self, request):
+        """
+        If we can get a valid IP from the request,
+        look up that address in the database to get the appropriate 
+        timezone and activate it. Else, use the default.
+        """
+
+        if not request:
+            return
+
+        if not db_loaded:
+            load_db()
+
+        tz = request.session.get('django_timezone')
+
+        if not tz:
+            # use the default timezone (settings.TIME_ZONE) for localhost
+~~            tz = timezone.get_default_timezone()
+
+            client_ip = get_ip_address_from_request(request)
+            ip_addrs = client_ip.split(',')
+            for ip in ip_addrs:
+                if is_valid_ip(ip) and not is_local_ip(ip):
+                    if ':' in ip:
+                        tz = db_v6.time_zone_by_addr(ip)
+                        break
+                    else:
+                        tz = db.time_zone_by_addr(ip)
+                        break
+
+        if tz:
+~~            timezone.activate(tz)
+            request.session['django_timezone'] = str(tz)
+            if getattr(settings, 'AUTH_USER_MODEL', 
+                       None) and getattr(request, 'user', None):
+~~                detected_timezone.send(sender=get_user_model(), 
+~~                                       instance=request.user, 
+~~                                       timezone=tz)
+        else:
+~~            timezone.deactivate()
+```
+
