Makes the Hook model available for extension (zapier#44)

* zapier#43: Make the Hook model available for extension as an Abstract model

 * Renamed Hook model to AbstractHook with the Meta abstract = True
 * The Hook model is the concrete implementation of the AbstractHook model

* zapier#43: Add ability to provide a custom find_and_fire_hook() through a HOOK_FINDER setting

* zapier#43: Add a 'Extend the Hook model' section in README

Author: tdruez

README.md

@@ -401,3 +401,41 @@ def deliver_hook_wrapper(target, payload, instance, hook):
 
 We also don't handle retries or cleanup. Generally, if you get a `410` or
 a bunch of `4xx` or `5xx`, you should delete the Hook and let the user know.
+
+### Extend the Hook model:
+
+The default `Hook` model fields can be extended using the `AbstractHook` model.
+For example, to add a `is_active` field on your hooks:
+
+```python
+### models.py ###
+
+from django.db import models
+from rest_hooks.models import AbstractHook
+
+class CustomHook(AbstractHook):
+    is_active = models.BooleanField(default=True)
+```
+
+The extended `CustomHook` model can be combined with a the `HOOK_FINDER` setting
+for advanced QuerySet filtering. 
+
+```python
+### settings.py ###
+
+HOOK_FINDER = 'path.to.find_and_fire_hook'
+
+### utils.py ###
+
+from .models import CustomHook
+
+def find_and_fire_hook(event_name, instance, **kwargs):
+    filters = {
+        'event': event_name,
+        'is_active': True,
+    }
+
+    hooks = CustomHook.objects.filter(**filters)
+    for hook in hooks:
+        hook.deliver_hook(instance)
+```

rest_hooks/models.py

@@ -32,18 +32,20 @@
 AUTH_USER_MODEL = getattr(settings, 'AUTH_USER_MODEL', 'auth.User')
 
 
-class Hook(models.Model):
+class AbstractHook(models.Model):
     """
     Stores a representation of a Hook.
     """
     created = models.DateTimeField(auto_now_add=True)
     updated = models.DateTimeField(auto_now=True)
 
-    user = models.ForeignKey(AUTH_USER_MODEL, related_name='hooks')
-    event = models.CharField('Event', max_length=64,
-                                      db_index=True)
+    user = models.ForeignKey(AUTH_USER_MODEL, related_name='%(class)ss')
+    event = models.CharField('Event', max_length=64, db_index=True)
     target = models.URLField('Target URL', max_length=255)
 
+    class Meta:
+        abstract = True
+
     def clean(self):
         """ Validation for events. """
         if self.event not in HOOK_EVENTS.keys():
@@ -107,6 +109,10 @@ def __unicode__(self):
         return u'{} => {}'.format(self.event, self.target)
 
 
+class Hook(AbstractHook):
+    pass
+
+
 ##############
 ### EVENTS ###
 ##############

rest_hooks/utils.py

@@ -1,3 +1,6 @@
+from django.conf import settings
+
+
 def get_module(path):
     """
     A modified duplicate from Django's built in backend
@@ -86,4 +89,7 @@ def distill_model_event(instance, model, action, user_override=None):
                     user_override = False
 
     if event_name:
-        find_and_fire_hook(event_name, instance, user_override=user_override)
+        finder = find_and_fire_hook
+        if getattr(settings, 'HOOK_FINDER', None):
+            finder = get_module(settings.HOOK_FINDER)
+        finder(event_name, instance, user_override=user_override)