Fixed #3534 -- newforms ModelChoiceField and ModelMultipleChoiceField no longer cache choices. Instead, they calculate choices via a fresh database query each time the widget is rendered and clean() is called

git-svn-id: http://code.djangoproject.com/svn/django/trunk@4552 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/modeltests/model_forms/models.py

@@ -289,6 +289,46 @@ existing Category instance.
 >>> Category.objects.get(id=3)
 <Category: Third>
 
+Here, we demonstrate that choices for a ForeignKey ChoiceField are determined
+at runtime, based on the data in the database when the form is displayed, not
+the data in the database when the form is instantiated.
+>>> ArticleForm = form_for_model(Article)
+>>> f = ArticleForm(auto_id=False)
+>>> print f.as_ul()
+<li>Headline: <input type="text" name="headline" maxlength="50" /></li>
+<li>Pub date: <input type="text" name="pub_date" /></li>
+<li>Writer: <select name="writer">
+<option value="" selected="selected">---------</option>
+<option value="1">Mike Royko</option>
+<option value="2">Bob Woodward</option>
+</select></li>
+<li>Article: <textarea name="article"></textarea></li>
+<li>Categories: <select multiple="multiple" name="categories">
+<option value="1">Entertainment</option>
+<option value="2">It&#39;s a test</option>
+<option value="3">Third</option>
+</select>  Hold down "Control", or "Command" on a Mac, to select more than one.</li>
+>>> Category.objects.create(name='Fourth', url='4th')
+<Category: Fourth>
+>>> Writer.objects.create(name='Carl Bernstein')
+<Writer: Carl Bernstein>
+>>> print f.as_ul()
+<li>Headline: <input type="text" name="headline" maxlength="50" /></li>
+<li>Pub date: <input type="text" name="pub_date" /></li>
+<li>Writer: <select name="writer">
+<option value="" selected="selected">---------</option>
+<option value="1">Mike Royko</option>
+<option value="2">Bob Woodward</option>
+<option value="3">Carl Bernstein</option>
+</select></li>
+<li>Article: <textarea name="article"></textarea></li>
+<li>Categories: <select multiple="multiple" name="categories">
+<option value="1">Entertainment</option>
+<option value="2">It&#39;s a test</option>
+<option value="3">Third</option>
+<option value="4">Fourth</option>
+</select>  Hold down "Control", or "Command" on a Mac, to select more than one.</li>
+
 # ModelChoiceField ############################################################
 
 >>> from django.newforms import ModelChoiceField, ModelMultipleChoiceField
@@ -311,13 +351,30 @@ ValidationError: [u'Select a valid choice. That choice is not one of the availab
 >>> f.clean(2)
 <Category: It's a test>
 
+# Add a Category object *after* the ModelChoiceField has already been
+# instantiated. This proves clean() checks the database during clean() rather
+# than caching it at time of instantiation.
+>>> Category.objects.create(name='Fifth', url='5th')
+<Category: Fifth>
+>>> f.clean(5)
+<Category: Fifth>
+
+# Delete a Category object *after* the ModelChoiceField has already been
+# instantiated. This proves clean() checks the database during clean() rather
+# than caching it at time of instantiation.
+>>> Category.objects.get(url='5th').delete()
+>>> f.clean(5)
+Traceback (most recent call last):
+...
+ValidationError: [u'Select a valid choice. That choice is not one of the available choices.']
+
 >>> f = ModelChoiceField(Category.objects.filter(pk=1), required=False)
 >>> print f.clean('')
 None
 >>> f.clean('')
 >>> f.clean('1')
 <Category: Entertainment>
->>> f.clean('2')
+>>> f.clean('100')
 Traceback (most recent call last):
 ...
 ValidationError: [u'Select a valid choice. That choice is not one of the available choices.']
@@ -345,29 +402,47 @@ ValidationError: [u'This field is required.']
 [<Category: Entertainment>, <Category: It's a test>]
 >>> f.clean((1, '2'))
 [<Category: Entertainment>, <Category: It's a test>]
->>> f.clean(['nonexistent'])
+>>> f.clean(['100'])
 Traceback (most recent call last):
 ...
-ValidationError: [u'Select a valid choice. nonexistent is not one of the available choices.']
+ValidationError: [u'Select a valid choice. 100 is not one of the available choices.']
 >>> f.clean('hello')
 Traceback (most recent call last):
 ...
 ValidationError: [u'Enter a list of values.']
+
+# Add a Category object *after* the ModelChoiceField has already been
+# instantiated. This proves clean() checks the database during clean() rather
+# than caching it at time of instantiation.
+>>> Category.objects.create(id=6, name='Sixth', url='6th')
+<Category: Sixth>
+>>> f.clean([6])
+[<Category: Sixth>]
+
+# Delete a Category object *after* the ModelChoiceField has already been
+# instantiated. This proves clean() checks the database during clean() rather
+# than caching it at time of instantiation.
+>>> Category.objects.get(url='6th').delete()
+>>> f.clean([6])
+Traceback (most recent call last):
+...
+ValidationError: [u'Select a valid choice. 6 is not one of the available choices.']
+
 >>> f = ModelMultipleChoiceField(Category.objects.all(), required=False)
 >>> f.clean([])
 []
 >>> f.clean(())
 []
->>> f.clean(['4'])
+>>> f.clean(['10'])
 Traceback (most recent call last):
 ...
-ValidationError: [u'Select a valid choice. 4 is not one of the available choices.']
->>> f.clean(['3', '4'])
+ValidationError: [u'Select a valid choice. 10 is not one of the available choices.']
+>>> f.clean(['3', '10'])
 Traceback (most recent call last):
 ...
-ValidationError: [u'Select a valid choice. 4 is not one of the available choices.']
->>> f.clean(['1', '5'])
+ValidationError: [u'Select a valid choice. 10 is not one of the available choices.']
+>>> f.clean(['1', '10'])
 Traceback (most recent call last):
 ...
-ValidationError: [u'Select a valid choice. 5 is not one of the available choices.']
+ValidationError: [u'Select a valid choice. 10 is not one of the available choices.']
 """}