Default queryset support

flexselect/__init__.py

@@ -1,4 +1,3 @@
-from collections import defaultdict
 from itertools import chain
 import hashlib
 import json
@@ -15,44 +14,53 @@
 FLEXSELECT = {
     'include_jquery': False,
 }
-try: FLEXSELECT.update(settings.FLEXSELECT)
-except AttributeError: pass
-
+
+try:
+    FLEXSELECT.update(settings.FLEXSELECT)
+except AttributeError:
+    pass
+
+
 def choices_from_queryset(queryset):
     """
-    Makes choices from a QuerySet in a format that is usable by the 
+    Makes choices from a QuerySet in a format that is usable by the
     django.forms.widget.Select widget.
-    
+
     queryset: An instance of django.db.models.query.QuerySet
     """
     return chain(
         [EMPTY_CHOICE],
         [(o.pk, smart_unicode(o)) for o in queryset],
     )
 
+
 def choices_from_instance(instance, widget):
     """
-    Builds choices from a model instance using the widgets queryset() method. 
-    If any of the widgets trigger_field fields is not defined on the instance or 
+    Builds choices from a model instance using the widgets queryset() method.
+    If any of the widgets trigger_field fields is not defined on the instance or
     the instance itself is None, None is returned.
-    
+
     instance: An instance of the model used on the current admin page.
     widget: A widget instance given to the FlexSelectWidget.
     """
     try:
         for trigger_field in widget.trigger_fields:
             getattr(instance, trigger_field)
     except (ObjectDoesNotExist, AttributeError):
-        return [('', widget.empty_choices_text(instance))]
-
+        try:
+            return choices_from_queryset(widget.default_queryset(instance))
+        except NotImplementedError:
+            return [('', widget.empty_choices_text(instance))]
+
     return choices_from_queryset(widget.queryset(instance))
-
+
+
 def details_from_instance(instance, widget):
     """
     Builds html from a model instance using the widgets details() method. If
-    any of the widgets trigger_field fields is not defined on the instance or 
+    any of the widgets trigger_field fields is not defined on the instance or
     the instance itself is None, None is returned.
-    
+
     instance: An instance of the model used on the current admin page.
     widget: A widget instance given to the FlexSelectWidget.
     """
@@ -64,58 +72,60 @@ def details_from_instance(instance, widget):
         return u''
     return widget.details(related_instance, instance)
 
+
 def instance_from_request(request, widget):
-        """
-        Returns a partial instance of the widgets model loading it with values
-        from a POST request.
-        """
-        items = dict(request.POST.items())
-        values = {}
-        for f in widget.base_field.model._meta.fields:
-            if f.name in items:
-                try:
-                    value = f.formfield().to_python(items[f.name])
-                    if value is not None:
-                        values[f.name] = value
-                except ValidationError:
-                    pass
-        return widget.base_field.model(**values)
-
+    """
+    Returns a partial instance of the widgets model loading it with values
+    from a POST request.
+    """
+    items = dict(request.POST.items())
+    values = {}
+    for f in widget.base_field.model._meta.fields:
+        if f.name in items:
+            try:
+                value = f.formfield().to_python(items[f.name])
+                if value is not None:
+                    values[f.name] = value
+            except ValidationError:
+                pass
+    return widget.base_field.model(**values)
+
+
 class FlexSelectWidget(Select):
+    """Instances of widgets with their hashed names as keys."""
     instances = {}
-    """ Instances of widgets with their hashed names as keys."""
-
+
     class Media:
         js = []
         if FLEXSELECT['include_jquery']:
             googlecdn = "https://ajax.googleapis.com/ajax/libs"
             js.append('%s/jquery/1.6.1/jquery.min.js' % googlecdn)
             js.append('%s/jqueryui/1.8.13/jquery-ui.min.js' % googlecdn)
         js.append('flexselect/js/flexselect.js')
-        
-    def __init__(self, base_field, modeladmin, request, *args, 
+
+    def __init__(self, base_field, modeladmin, request, *args,
                  **kwargs):
-            
+
         self.base_field = base_field
         self.modeladmin = modeladmin
         self.request = request
-        
+
         self.hashed_name = self._hashed_name()
         FlexSelectWidget.instances[self.hashed_name] = self
         super(FlexSelectWidget, self).__init__(*args, **kwargs)
-        
+
     def _hashed_name(self):
         """
-        Each widget will be unique by the name of the field and the class name 
+        Each widget will be unique by the name of the field and the class name
         of the model admin.
         """
         salted_string = "".join([
-              settings.SECRET_KEY,
-              self.base_field.name, 
-              self.modeladmin.__class__.__name__,         
+            settings.SECRET_KEY,
+            self.base_field.name,
+            self.modeladmin.__class__.__name__,
         ])
         return "_%s" % hashlib.sha1(salted_string).hexdigest()
-        
+
     def _get_instance(self):
         """
         Returns a model instance from the url in the admin page.
@@ -129,7 +139,7 @@ def _get_instance(self):
                 return self.modeladmin.get_object(self.request, object_id)
             except ValueError:
                 return None
-    
+
     def _build_js(self):
         """
         Adds the widgets hashed_name as the key with an array of its trigger_fields
@@ -141,42 +151,42 @@ def _build_js(self):
                 flexselect.fields = flexselect.fields || {};
                 flexselect.fields.%s = %s;
             </script>""" % (
-                self.hashed_name, json.dumps({ 
-                  'base_field': self.base_field.name,
-                  'trigger_fields': self.trigger_fields,})
-            )
-
-
+            self.hashed_name, json.dumps({
+                'base_field': self.base_field.name,
+                'trigger_fields': self.trigger_fields
+            }))
+
     def render(self, name, value, attrs=None, choices=(), *args, **kwargs):
         """
-        Overrides. Reduces the choices by calling the widgets queryset() 
-        method and adds a details <span> that is filled with the widgets 
+        Overrides. Reduces the choices by calling the widgets queryset()
+        method and adds a details <span> that is filled with the widgets
         details() method.
         """
         instance = self._get_instance()
         self.choices = choices_from_instance(instance, self)
         html = []
         html.append(super(FlexSelectWidget, self).render(
-            name, value, attrs=attrs, 
+            name, value, attrs=attrs,
             *args, **kwargs
         ))
         html.append(self._build_js())
         html.append('<span class="flexselect_details">')
         html.append(details_from_instance(instance, self))
         html.append('</span>')
         return mark_safe("".join(html))
-    
+
     # Methods and properties that must be implemented.
-      
+
     trigger_fields = []
-    
+
     def details(self, base_field_instance, instance):
         raise NotImplementedError
-    
+
     def queryset(self, instance):
         raise NotImplementedError
-
+
+    def default_queryset(self, instance):
+        raise NotImplementedError
+
     def empty_choices_text(self, instance):
         raise NotImplementedError
-
-

flexselect/urls.py

@@ -1,5 +1,5 @@
 from django.conf.urls.defaults import *
 
-urlpatterns = patterns('flexselect.views',
-    (r'field_changed', 'field_changed'),
+urlpatterns = patterns(
+    'flexselect.views', (r'field_changed', 'field_changed'),
 )

flexselect/views.py

@@ -4,26 +4,27 @@
 from django.forms.widgets import Select
 from django.contrib.auth.decorators import login_required
 
-from flexselect import (FlexSelectWidget, choices_from_instance, 
+from flexselect import (FlexSelectWidget, choices_from_instance,
                         details_from_instance, instance_from_request)
 
+
 @login_required
 def field_changed(request):
     """
     Ajax callback called when a trigger field or base field has changed. Returns
     html for new options and details for the dependent field as json.
     """
     hashed_name = request.POST.__getitem__('hashed_name')
-    widget = FlexSelectWidget.instances[hashed_name]    
+    widget = FlexSelectWidget.instances[hashed_name]
     instance = instance_from_request(request, widget)
-    
+
     if bool(int(request.POST.__getitem__('include_options'))):
         choices = choices_from_instance(instance, widget)
         options = Select(choices=choices).render_options([], [])
     else:
         options = None
-    
+
     return HttpResponse(json.dumps({
-        'options' : options,
+        'options': options,
         'details': details_from_instance(instance, widget),
-        }), mimetype='application/json')
+    }), mimetype='application/json')