Fixed #12024: Changed admin code to avoid raising an exception when a field listed

in raw_id_fields has limit_choices_to specified as a Q object. 

Tweaked a test to trigger the condition and verify the fix. 

Finally, documented that limit_choices_to specified as a Q object has no effect 
on the choices available for fields listed in raw_id_fields, and removed another 
incorrect note that claimed limit_choices_to had no effect on inlines in the admin.



git-svn-id: http://code.djangoproject.com/svn/django/trunk@12728 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/admin/widgets.py

@@ -133,7 +133,7 @@ class ForeignKeyRawIdWidget(forms.TextInput):
 
     def base_url_parameters(self):
         params = {}
-        if self.rel.limit_choices_to:
+        if self.rel.limit_choices_to and hasattr(self.rel.limit_choices_to, 'items'):
             items = []
             for k, v in self.rel.limit_choices_to.items():
                 if isinstance(v, list):

docs/ref/models/fields.txt

@@ -872,10 +872,10 @@ define the details of how the relation works.
     current date/time to be chosen.
 
     Instead of a dictionary this can also be a :class:`~django.db.models.Q`
-    object for more :ref:`complex queries <complex-lookups-with-q>`.
-
-    ``limit_choices_to`` has no effect on the inline FormSets that are created
-    to display related objects in the admin.
+    object for more :ref:`complex queries <complex-lookups-with-q>`. However, 
+    if ``limit_choices_to`` is a :class:`~django.db.models.Q` object then it 
+    will only have an effect on the choices available in the admin when the 
+    field is not listed in ``raw_id_fields`` in the ``ModelAdmin`` for the model.
 
 .. attribute:: ForeignKey.related_name
 

tests/regressiontests/admin_widgets/models.py

@@ -49,7 +49,7 @@ class Inventory(models.Model):
       return self.name
 
 class Event(models.Model):
-    band = models.ForeignKey(Band)
+    band = models.ForeignKey(Band, limit_choices_to=models.Q(pk__gt=0))
     start_date = models.DateField(blank=True, null=True)
     start_time = models.TimeField(blank=True, null=True)
     description = models.TextField(blank=True)