Ticket #8648: 8648.diff

django/db/models/fields/related.py

@@ -686 +686 @@
         setattr(cls, related.get_accessor_name(), ForeignRelatedObjectsDescriptor(related))
         
     def formfield(self, **kwargs):
-        defaults = {'form_class': forms.ModelChoiceField, 'queryset': self.rel.to._default_manager.complex_filter(self.rel.limit_choices_to)}
+        defaults = {
+            'form_class': forms.ModelChoiceField,
+            'queryset': self.rel.to._default_manager.complex_filter(
+                                                    self.rel.limit_choices_to),
+            'to_field_name': self.rel.field_name,
+        }
         defaults.update(kwargs)
         return super(ForeignKey, self).formfield(**defaults)
 

django/forms/models.py

@@ -460 +460 @@
         if self.field.cache_choices:
             if self.field.choice_cache is None:
                 self.field.choice_cache = [
-                    (obj.pk, self.field.label_from_instance(obj))
-                    for obj in self.queryset.all()
+                    self.choice(obj) for obj in self.queryset.all()
                 ]
             for choice in self.field.choice_cache:
                 yield choice
         else:
             for obj in self.queryset.all():
-                yield (obj.pk, self.field.label_from_instance(obj))
+                yield self.choice(obj)
 
+    def choice(self, obj):
+        if self.field.to_field_name:
+            key = getattr(obj, self.field.to_field_name)
+        else:
+            key = obj.pk
+        return (key, self.field.label_from_instance(obj))
+
+
 class ModelChoiceField(ChoiceField):
     """A ChoiceField whose choices are a model QuerySet."""
     # This class is a subclass of ChoiceField for purity, but it doesn't
@@ -480 +487 @@
 
     def __init__(self, queryset, empty_label=u"---------", cache_choices=False,
                  required=True, widget=None, label=None, initial=None,
-                 help_text=None, *args, **kwargs):
+                 help_text=None, to_field_name=None, *args, **kwargs):
         self.empty_label = empty_label
         self.cache_choices = cache_choices
 
@@ -490 +497 @@
                        *args, **kwargs)
         self.queryset = queryset
         self.choice_cache = None
+        self.to_field_name = to_field_name
 
     def _get_queryset(self):
         return self._queryset
@@ -532 +540 @@
         if value in EMPTY_VALUES:
             return None
         try:
-            value = self.queryset.get(pk=value)
+            key = self.to_field_name or 'pk'
+            value = self.queryset.get(**{key: value})
         except self.queryset.model.DoesNotExist:
             raise ValidationError(self.error_messages['invalid_choice'])
         return value

tests/modeltests/model_forms/models.py

@@ -120 +120 @@
 class ArticleStatus(models.Model):
     status = models.CharField(max_length=2, choices=ARTICLE_STATUS_CHAR, blank=True, null=True)
 
+class Inventory(models.Model):
+   barcode = models.PositiveIntegerField(unique=True)
+   parent = models.ForeignKey('self', to_field='barcode', blank=True, null=True)
+   name = models.CharField(blank=False, max_length=20)
+
+   def __unicode__(self):
+      return self.name
+
 __test__ = {'API_TESTS': """
 >>> from django import forms
 >>> from django.forms.models import ModelForm, model_to_dict
@@ -1152 +1160 @@
 ...
 ValidationError: [u'Select a valid choice. z is not one of the available choices.']
 
+# Foreign keys which use to_field #############################################
+
+>>> apple = Inventory.objects.create(barcode=86, name='Apple')
+>>> pear = Inventory.objects.create(barcode=22, name='Pear')
+>>> core = Inventory.objects.create(barcode=87, name='Core', parent=apple)
+
+>>> field = ModelChoiceField(Inventory.objects.all(), to_field_name='barcode')
+>>> for choice in field.choices:
+...     print choice
+(u'', u'---------')
+(86, u'Apple')
+(22, u'Pear')
+(87, u'Core')
+
+>>> class InventoryForm(ModelForm):
+...     class Meta:
+...         model = Inventory
+>>> form = InventoryForm(instance=core)
+>>> print form['parent']
+<select name="parent" id="id_parent">
+<option value="">---------</option>
+<option value="86" selected="selected">Apple</option>
+<option value="22">Pear</option>
+<option value="87">Core</option>
+</select>
+
+>>> data = model_to_dict(core)
+>>> data['parent'] = '22'
+>>> form = InventoryForm(data=data, instance=core)
+>>> core = form.save()
+>>> core.parent
+<Inventory: Pear>
 """}