newforms-admin: Fixed #6075 -- Implemented max_num on formsets and model formsets. Added a hook on InlineModelAdmin to customize in the admin interface.

git-svn-id: http://code.djangoproject.com/svn/django/branches/newforms-admin@7613 bcc190cf-cafb-0310-a4f2-bffc1f526a37

7 files changed, 170 insertions, 26 deletions

diff --git a/django/contrib/admin/options.py b/django/contrib/admin/options.py
index 1aa56f2c91..8ba543d4a7 100644
--- a/django/contrib/admin/options.py
+++ b/django/contrib/admin/options.py
@@ -699,6 +699,7 @@ class InlineModelAdmin(BaseModelAdmin):
     fk_name = None
     formset = BaseInlineFormset
     extra = 3
+    max_num = 0
     template = None
     verbose_name = None
     verbose_name_plural = None
@@ -722,7 +723,7 @@ class InlineModelAdmin(BaseModelAdmin):
         return inlineformset_factory(self.parent_model, self.model,
             form=self.form, formset=self.formset, fk_name=self.fk_name,
             fields=fields, formfield_callback=self.formfield_for_dbfield,
-            extra=self.extra)
+            extra=self.extra, max_num=self.max_num)
 
     def get_fieldsets(self, request, obj=None):
         if self.declared_fieldsets:
diff --git a/django/newforms/formsets.py b/django/newforms/formsets.py
index 2edc673a32..03f5278c30 100644
--- a/django/newforms/formsets.py
+++ b/django/newforms/formsets.py
@@ -10,6 +10,7 @@ __all__ = ('BaseFormSet', 'all_valid')
 # special field names
 TOTAL_FORM_COUNT = 'TOTAL_FORMS'
 INITIAL_FORM_COUNT = 'INITIAL_FORMS'
+MAX_FORM_COUNT = 'MAX_FORMS'
 ORDERING_FIELD_NAME = 'ORDER'
 DELETION_FIELD_NAME = 'DELETE'
 
@@ -22,6 +23,7 @@ class ManagementForm(Form):
     def __init__(self, *args, **kwargs):
         self.base_fields[TOTAL_FORM_COUNT] = IntegerField(widget=HiddenInput)
         self.base_fields[INITIAL_FORM_COUNT] = IntegerField(widget=HiddenInput)
+        self.base_fields[MAX_FORM_COUNT] = IntegerField(widget=HiddenInput)
         super(ManagementForm, self).__init__(*args, **kwargs)
 
 class BaseFormSet(StrAndUnicode):
@@ -29,7 +31,7 @@ class BaseFormSet(StrAndUnicode):
     A collection of instances of the same Form class.
     """
     def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None,
-            initial=None, error_class=ErrorList):
+                 initial=None, error_class=ErrorList):
         self.is_bound = data is not None or files is not None
         self.prefix = prefix or 'form'
         self.auto_id = auto_id
@@ -45,18 +47,25 @@ class BaseFormSet(StrAndUnicode):
             if self.management_form.is_valid():
                 self._total_form_count = self.management_form.cleaned_data[TOTAL_FORM_COUNT]
                 self._initial_form_count = self.management_form.cleaned_data[INITIAL_FORM_COUNT]
+                self._max_form_count = self.management_form.cleaned_data[MAX_FORM_COUNT]
             else:
                 raise ValidationError('ManagementForm data is missing or has been tampered with')
         else:
             if initial:
                 self._initial_form_count = len(initial)
+                if self._initial_form_count > self._max_form_count and self._max_form_count > 0:
+                    self._initial_form_count = self._max_form_count
                 self._total_form_count = self._initial_form_count + self.extra
             else:
                 self._initial_form_count = 0
                 self._total_form_count = self.extra
-            initial = {TOTAL_FORM_COUNT: self._total_form_count, INITIAL_FORM_COUNT: self._initial_form_count}
+            if self._total_form_count > self._max_form_count and self._max_form_count > 0:
+                self._total_form_count = self._max_form_count
+            initial = {TOTAL_FORM_COUNT: self._total_form_count,
+                       INITIAL_FORM_COUNT: self._initial_form_count,
+                       MAX_FORM_COUNT: self._max_form_count}
             self.management_form = ManagementForm(initial=initial, auto_id=self.auto_id, prefix=self.prefix)
-
+        
         # construct the forms in the formset
         self._construct_forms()
 
@@ -266,9 +275,11 @@ class BaseFormSet(StrAndUnicode):
         return mark_safe(u'\n'.join([unicode(self.management_form), forms]))
 
 def formset_factory(form, formset=BaseFormSet, extra=1, can_order=False,
-                    can_delete=False):
+                    can_delete=False, max_num=0):
     """Return a FormSet for the given form class."""
-    attrs = {'form': form, 'extra': extra, 'can_order': can_order, 'can_delete': can_delete}
+    attrs = {'form': form, 'extra': extra,
+             'can_order': can_order, 'can_delete': can_delete,
+             '_max_form_count': max_num}
     return type(form.__name__ + 'FormSet', (formset,), attrs)
 
 def all_valid(formsets):
diff --git a/django/newforms/models.py b/django/newforms/models.py
index b9baced609..a60c1793a7 100644
--- a/django/newforms/models.py
+++ b/django/newforms/models.py
@@ -305,7 +305,11 @@ class BaseModelFormSet(BaseFormSet):
                  queryset=None, **kwargs):
         self.queryset = queryset
         defaults = {'data': data, 'files': files, 'auto_id': auto_id, 'prefix': prefix}
-        defaults['initial'] = [model_to_dict(obj) for obj in self.get_queryset()]
+        if self._max_form_count > 0:
+            qs = self.get_queryset()[:self._max_form_count]
+        else:
+            qs = self.get_queryset()
+        defaults['initial'] = [model_to_dict(obj) for obj in qs]
         defaults.update(kwargs)
         super(BaseModelFormSet, self).__init__(**defaults)
 
@@ -369,15 +373,16 @@ class BaseModelFormSet(BaseFormSet):
         super(BaseModelFormSet, self).add_fields(form, index)
 
 def modelformset_factory(model, form=ModelForm, formfield_callback=lambda f: f.formfield(),
-                          formset=BaseModelFormSet,
-                          extra=1, can_delete=False, can_order=False,
-                          fields=None, exclude=None):
+                         formset=BaseModelFormSet,
+                         extra=1, can_delete=False, can_order=False,
+                         max_num=0, fields=None, exclude=None):
     """
     Returns a FormSet class for the given Django model class.
     """
     form = modelform_factory(model, form=form, fields=fields, exclude=exclude,
-                              formfield_callback=formfield_callback)
-    FormSet = formset_factory(form, formset, extra=extra, can_order=can_order, can_delete=can_delete)
+                             formfield_callback=formfield_callback)
+    FormSet = formset_factory(form, formset, extra=extra, max_num=max_num,
+                              can_order=can_order, can_delete=can_delete)
     FormSet.model = model
     return FormSet
 
@@ -395,9 +400,8 @@ class BaseInlineFormset(BaseModelFormSet):
         super(BaseInlineFormset, self).__init__(data, files, prefix=self.rel_name)
     
     def _construct_forms(self):
-        from django.newforms.formsets import INITIAL_FORM_COUNT
         if self.save_as_new:
-            self._total_form_count = self.management_form.cleaned_data[INITIAL_FORM_COUNT]
+            self._total_form_count = self._initial_form_count
             self._initial_form_count = 0
         super(BaseInlineFormset, self)._construct_forms()
 
@@ -443,10 +447,10 @@ def _get_foreign_key(parent_model, model, fk_name=None):
 
 
 def inlineformset_factory(parent_model, model, form=ModelForm,
-                           formset=BaseInlineFormset, fk_name=None,
-                           fields=None, exclude=None,
-                           extra=3, can_order=False, can_delete=True,
-                           formfield_callback=lambda f: f.formfield()):
+                          formset=BaseInlineFormset, fk_name=None,
+                          fields=None, exclude=None,
+                          extra=3, can_order=False, can_delete=True, max_num=0,
+                          formfield_callback=lambda f: f.formfield()):
     """
     Returns an ``InlineFormset`` for the given kwargs.
 
@@ -464,7 +468,7 @@ def inlineformset_factory(parent_model, model, form=ModelForm,
                                     formfield_callback=formfield_callback,
                                     formset=formset,
                                     extra=extra, can_delete=can_delete, can_order=can_order,
-                                    fields=fields, exclude=exclude)
+                                    fields=fields, exclude=exclude, max_num=max_num)
     FormSet.fk = fk
     return FormSet
 
diff --git a/docs/modelforms.txt b/docs/modelforms.txt
index b9332bc59e..f2222c1fc0 100644
--- a/docs/modelforms.txt
+++ b/docs/modelforms.txt
@@ -449,6 +449,34 @@ model instances without any database interaction::
 This gives you the ability to attach data to the instances before saving them
 to the database.
 
+Limiting the number of objects editable
+---------------------------------------
+
+Similar to regular formsets you can use the ``max_num`` parameter to
+``modelformset_factory`` to limit the number of forms displayed. With
+model formsets this will properly limit the query to only select the maximum
+number of objects needed::
+
+    >>> Author.objects.order_by('name')
+    [<Author: Charles Baudelaire>, <Author: Paul Verlaine>, <Author: Walt Whitman>]
+    
+    >>> AuthorFormSet = modelformset_factory(Author, max_num=2, extra=1)
+    >>> formset = AuthorFormSet(queryset=Author.objects.order_by('name'))
+    >>> formset.initial
+    [{'id': 1, 'name': u'Charles Baudelaire'}, {'id': 3, 'name': u'Paul Verlaine'}]
+
+If the value of ``max_num`` is less than the total objects returned it will
+fill the rest with extra forms::
+
+    >>> AuthorFormSet = modelformset_factory(Author, max_num=4, extra=1)
+    >>> formset = AuthorFormSet(queryset=Author.objects.order_by('name'))
+    >>> for form in formset.forms:
+    ...     print form.as_table()
+    <tr><th><label for="id_form-0-name">Name:</label></th><td><input id="id_form-0-name" type="text" name="form-0-name" value="Charles Baudelaire" maxlength="100" /><input type="hidden" name="form-0-id" value="1" id="id_form-0-id" /></td></tr>
+    <tr><th><label for="id_form-1-name">Name:</label></th><td><input id="id_form-1-name" type="text" name="form-1-name" value="Paul Verlaine" maxlength="100" /><input type="hidden" name="form-1-id" value="3" id="id_form-1-id" /></td></tr>
+    <tr><th><label for="id_form-2-name">Name:</label></th><td><input id="id_form-2-name" type="text" name="form-2-name" value="Walt Whitman" maxlength="100" /><input type="hidden" name="form-2-id" value="2" id="id_form-2-id" /></td></tr>
+    <tr><th><label for="id_form-3-name">Name:</label></th><td><input id="id_form-3-name" type="text" name="form-3-name" maxlength="100" /><input type="hidden" name="form-3-id" id="id_form-3-id" /></td></tr>
+
 Using ``inlineformset_factory``
 -------------------------------
 
diff --git a/docs/newforms.txt b/docs/newforms.txt
index ad3f81cb6c..f81fcfc8dc 100644
--- a/docs/newforms.txt
+++ b/docs/newforms.txt
@@ -2230,6 +2230,22 @@ There are now a total of three forms showing above. One for the initial data
 that was passed in and two extra forms. Also note that we are passing in a
 list of dictionaries as the initial data.
 
+Limiting the maximum number of forms
+------------------------------------
+
+The ``max_num`` parameter to ``formset_factory`` gives you the ability to
+force the maximum number of forms the formset will display::
+
+    >>> ArticleFormSet = formset_factory(ArticleForm, extra=2, max_num=1)
+    >>> formset = ArticleFormset()
+    >>> for form in formset.forms:
+    ...     print form.as_table()
+    <tr><th><label for="id_form-0-title">Title:</label></th><td><input type="text" name="form-0-title" id="id_form-0-title" /></td></tr>
+    <tr><th><label for="id_form-0-pub_date">Pub date:</label></th><td><input type="text" name="form-0-pub_date" id="id_form-0-pub_date" /></td></tr>
+
+The default value of ``max_num`` is ``0`` which is the same as saying put no
+limit on the number forms displayed.
+
 Formset validation
 ------------------
 
diff --git a/tests/modeltests/model_formsets/models.py b/tests/modeltests/model_formsets/models.py
index 93bc80ee72..93519a4421 100644
--- a/tests/modeltests/model_formsets/models.py
+++ b/tests/modeltests/model_formsets/models.py
@@ -31,6 +31,7 @@ __test__ = {'API_TESTS': """
 >>> data = {
 ...     'form-TOTAL_FORMS': '3', # the number of forms rendered
 ...     'form-INITIAL_FORMS': '0', # the number of forms with initial data
+...     'form-MAX_FORMS': '0', # the max number of forms
 ...     'form-0-name': 'Charles Baudelaire',
 ...     'form-1-name': 'Arthur Rimbaud',
 ...     'form-2-name': '',
@@ -68,6 +69,7 @@ them in alphabetical order by name.
 >>> data = {
 ...     'form-TOTAL_FORMS': '3', # the number of forms rendered
 ...     'form-INITIAL_FORMS': '2', # the number of forms with initial data
+...     'form-MAX_FORMS': '0', # the max number of forms
 ...     'form-0-id': '2',
 ...     'form-0-name': 'Arthur Rimbaud',
 ...     'form-1-id': '1',
@@ -111,6 +113,7 @@ deltetion, make sure we don't save that form.
 >>> data = {
 ...     'form-TOTAL_FORMS': '4', # the number of forms rendered
 ...     'form-INITIAL_FORMS': '3', # the number of forms with initial data
+...     'form-MAX_FORMS': '0', # the max number of forms
 ...     'form-0-id': '2',
 ...     'form-0-name': 'Arthur Rimbaud',
 ...     'form-1-id': '1',
@@ -140,6 +143,7 @@ Let's edit a record to ensure save only returns that one record.
 >>> data = {
 ...     'form-TOTAL_FORMS': '4', # the number of forms rendered
 ...     'form-INITIAL_FORMS': '3', # the number of forms with initial data
+...     'form-MAX_FORMS': '0', # the max number of forms
 ...     'form-0-id': '2',
 ...     'form-0-name': 'Walt Whitman',
 ...     'form-1-id': '1',
@@ -158,6 +162,22 @@ True
 >>> formset.save()
 [<Author: Walt Whitman>]
 
+Test the behavior of max_num with model formsets. It should properly limit
+the queryset to reduce the amount of objects being pulled in when not being
+used.
+
+>>> qs = Author.objects.order_by('name')
+
+>>> AuthorFormSet = modelformset_factory(Author, max_num=2)
+>>> formset = AuthorFormSet(queryset=qs)
+>>> formset.initial
+[{'id': 1, 'name': u'Charles Baudelaire'}, {'id': 3, 'name': u'Paul Verlaine'}]
+
+>>> AuthorFormSet = modelformset_factory(Author, max_num=3)
+>>> formset = AuthorFormSet(queryset=qs)
+>>> formset.initial
+[{'id': 1, 'name': u'Charles Baudelaire'}, {'id': 3, 'name': u'Paul Verlaine'}, {'id': 2, 'name': u'Walt Whitman'}]
+
 # Inline Formsets ############################################################
 
 We can also create a formset that is tied to a parent model. This is how the
@@ -178,6 +198,7 @@ admin system's edit inline functionality works.
 >>> data = {
 ...     'book_set-TOTAL_FORMS': '3', # the number of forms rendered
 ...     'book_set-INITIAL_FORMS': '0', # the number of forms with initial data
+...     'book_set-MAX_FORMS': '0', # the max number of forms
 ...     'book_set-0-title': 'Les Fleurs du Mal',
 ...     'book_set-1-title': '',
 ...     'book_set-2-title': '',
@@ -212,6 +233,7 @@ book.
 >>> data = {
 ...     'book_set-TOTAL_FORMS': '3', # the number of forms rendered
 ...     'book_set-INITIAL_FORMS': '1', # the number of forms with initial data
+...     'book_set-MAX_FORMS': '0', # the max number of forms
 ...     'book_set-0-id': '1',
 ...     'book_set-0-title': 'Les Fleurs du Mal',
 ...     'book_set-1-title': 'Le Spleen de Paris',
@@ -238,6 +260,7 @@ This is used in the admin for save_as functionality.
 >>> data = {
 ...     'book_set-TOTAL_FORMS': '3', # the number of forms rendered
 ...     'book_set-INITIAL_FORMS': '2', # the number of forms with initial data
+...     'book_set-MAX_FORMS': '0', # the max number of forms
 ...     'book_set-0-id': '1',
 ...     'book_set-0-title': 'Les Fleurs du Mal',
 ...     'book_set-1-id': '2',
diff --git a/tests/regressiontests/forms/formsets.py b/tests/regressiontests/forms/formsets.py
index 4cccb10d09..dedc0a8e52 100644
--- a/tests/regressiontests/forms/formsets.py
+++ b/tests/regressiontests/forms/formsets.py
@@ -20,7 +20,7 @@ but we'll look at how to do so later.
 
 >>> formset = ChoiceFormSet(auto_id=False, prefix='choices')
 >>> print formset
-<input type="hidden" name="choices-TOTAL_FORMS" value="1" /><input type="hidden" name="choices-INITIAL_FORMS" value="0" />
+<input type="hidden" name="choices-TOTAL_FORMS" value="1" /><input type="hidden" name="choices-INITIAL_FORMS" value="0" /><input type="hidden" name="choices-MAX_FORMS" value="0" />
 <tr><th>Choice:</th><td><input type="text" name="choices-0-choice" /></td></tr>
 <tr><th>Votes:</th><td><input type="text" name="choices-0-votes" /></td></tr>
 
@@ -34,6 +34,7 @@ the TOTAL_FORMS field appropriately.
 >>> data = {
 ...     'choices-TOTAL_FORMS': '1', # the number of forms rendered
 ...     'choices-INITIAL_FORMS': '0', # the number of forms with initial data
+...     'choices-MAX_FORMS': '0', # the max number of forms
 ...     'choices-0-choice': 'Calexico',
 ...     'choices-0-votes': '100',
 ... }
@@ -60,6 +61,7 @@ any of the forms.
 >>> data = {
 ...     'choices-TOTAL_FORMS': '1', # the number of forms rendered
 ...     'choices-INITIAL_FORMS': '0', # the number of forms with initial data
+...     'choices-MAX_FORMS': '0', # the max number of forms
 ...     'choices-0-choice': 'Calexico',
 ...     'choices-0-votes': '',
 ... }
@@ -90,6 +92,7 @@ Let's simulate what would happen if we submitted this form.
 >>> data = {
 ...     'choices-TOTAL_FORMS': '2', # the number of forms rendered
 ...     'choices-INITIAL_FORMS': '1', # the number of forms with initial data
+...     'choices-MAX_FORMS': '0', # the max number of forms
 ...     'choices-0-choice': 'Calexico',
 ...     'choices-0-votes': '100',
 ...     'choices-1-choice': '',
@@ -111,6 +114,7 @@ handle that later.
 >>> data = {
 ...     'choices-TOTAL_FORMS': '2', # the number of forms rendered
 ...     'choices-INITIAL_FORMS': '1', # the number of forms with initial data
+...     'choices-MAX_FORMS': '0', # the max number of forms
 ...     'choices-0-choice': 'Calexico',
 ...     'choices-0-votes': '100',
 ...     'choices-1-choice': 'The Decemberists',
@@ -130,6 +134,7 @@ handle that case later.
 >>> data = {
 ...     'choices-TOTAL_FORMS': '2', # the number of forms rendered
 ...     'choices-INITIAL_FORMS': '1', # the number of forms with initial data
+...     'choices-MAX_FORMS': '0', # the max number of forms
 ...     'choices-0-choice': '', # deleted value
 ...     'choices-0-votes': '', # deleted value
 ...     'choices-1-choice': '',
@@ -167,6 +172,7 @@ number of forms to be completed.
 >>> data = {
 ...     'choices-TOTAL_FORMS': '3', # the number of forms rendered
 ...     'choices-INITIAL_FORMS': '0', # the number of forms with initial data
+...     'choices-MAX_FORMS': '0', # the max number of forms
 ...     'choices-0-choice': '',
 ...     'choices-0-votes': '',
 ...     'choices-1-choice': '',
@@ -187,6 +193,7 @@ We can just fill out one of the forms.
 >>> data = {
 ...     'choices-TOTAL_FORMS': '3', # the number of forms rendered
 ...     'choices-INITIAL_FORMS': '0', # the number of forms with initial data
+...     'choices-MAX_FORMS': '0', # the max number of forms
 ...     'choices-0-choice': 'Calexico',
 ...     'choices-0-votes': '100',
 ...     'choices-1-choice': '',
@@ -207,6 +214,7 @@ And once again, if we try to partially complete a form, validation will fail.
 >>> data = {
 ...     'choices-TOTAL_FORMS': '3', # the number of forms rendered
 ...     'choices-INITIAL_FORMS': '0', # the number of forms with initial data
+...     'choices-MAX_FORMS': '0', # the max number of forms
 ...     'choices-0-choice': 'Calexico',
 ...     'choices-0-votes': '100',
 ...     'choices-1-choice': 'The Decemberists',
@@ -267,6 +275,7 @@ To delete something, we just need to set that form's special delete field to
 >>> data = {
 ...     'choices-TOTAL_FORMS': '3', # the number of forms rendered
 ...     'choices-INITIAL_FORMS': '2', # the number of forms with initial data
+...     'choices-MAX_FORMS': '0', # the max number of forms
 ...     'choices-0-choice': 'Calexico',
 ...     'choices-0-votes': '100',
 ...     'choices-0-DELETE': '',
@@ -316,6 +325,7 @@ something at the front of the list, you'd need to set it's order to 0.
 >>> data = {
 ...     'choices-TOTAL_FORMS': '3', # the number of forms rendered
 ...     'choices-INITIAL_FORMS': '2', # the number of forms with initial data
+...     'choices-MAX_FORMS': '0', # the max number of forms
 ...     'choices-0-choice': 'Calexico',
 ...     'choices-0-votes': '100',
 ...     'choices-0-ORDER': '1',
@@ -342,6 +352,7 @@ they will be sorted below everything else.
 >>> data = {
 ...     'choices-TOTAL_FORMS': '4', # the number of forms rendered
 ...     'choices-INITIAL_FORMS': '3', # the number of forms with initial data
+...     'choices-MAX_FORMS': '0', # the max number of forms
 ...     'choices-0-choice': 'Calexico',
 ...     'choices-0-votes': '100',
 ...     'choices-0-ORDER': '1',
@@ -403,6 +414,7 @@ Let's delete Fergie, and put The Decemberists ahead of Calexico.
 >>> data = {
 ...     'choices-TOTAL_FORMS': '4', # the number of forms rendered
 ...     'choices-INITIAL_FORMS': '3', # the number of forms with initial data
+...     'choices-MAX_FORMS': '0', # the max number of forms
 ...     'choices-0-choice': 'Calexico',
 ...     'choices-0-votes': '100',
 ...     'choices-0-ORDER': '1',
@@ -444,12 +456,7 @@ error if there are any duplicates.
 ...     name = CharField()
 ...
 
->>> class FavoriteDrinksFormSet(BaseFormSet):
-...     form = FavoriteDrinkForm
-...     extra = 2
-...     can_order = False
-...     can_delete = False
-...
+>>> class BaseFavoriteDrinksFormSet(BaseFormSet):
 ...     def clean(self):
 ...         seen_drinks = []
 ...         for drink in self.cleaned_data:
@@ -458,11 +465,15 @@ error if there are any duplicates.
 ...             seen_drinks.append(drink['name'])
 ...
 
+>>> FavoriteDrinksFormSet = formset_factory(FavoriteDrinkForm,
+...     formset=BaseFavoriteDrinksFormSet, extra=3)
+
 We start out with a some duplicate data.
 
 >>> data = {
 ...     'drinks-TOTAL_FORMS': '2', # the number of forms rendered
 ...     'drinks-INITIAL_FORMS': '0', # the number of forms with initial data
+...     'drinks-MAX_FORMS': '0', # the max number of forms
 ...     'drinks-0-name': 'Gin and Tonic',
 ...     'drinks-1-name': 'Gin and Tonic',
 ... }
@@ -484,6 +495,7 @@ Make sure we didn't break the valid case.
 >>> data = {
 ...     'drinks-TOTAL_FORMS': '2', # the number of forms rendered
 ...     'drinks-INITIAL_FORMS': '0', # the number of forms with initial data
+...     'drinks-MAX_FORMS': '0', # the max number of forms
 ...     'drinks-0-name': 'Gin and Tonic',
 ...     'drinks-1-name': 'Bloody Mary',
 ... }
@@ -494,6 +506,55 @@ True
 >>> for error in formset.non_form_errors():
 ...     print error
 
+# Limiting the maximum number of forms ########################################
+
+# Base case for max_num.
+
+>>> LimitedFavoriteDrinkFormSet = formset_factory(FavoriteDrinkForm, extra=5, max_num=2)
+>>> formset = LimitedFavoriteDrinkFormSet()
+>>> for form in formset.forms:
+...     print form
+<tr><th><label for="id_form-0-name">Name:</label></th><td><input type="text" name="form-0-name" id="id_form-0-name" /></td></tr>
+<tr><th><label for="id_form-1-name">Name:</label></th><td><input type="text" name="form-1-name" id="id_form-1-name" /></td></tr>
+
+# Ensure the that max_num has no affect when extra is less than max_forms.
+
+>>> LimitedFavoriteDrinkFormSet = formset_factory(FavoriteDrinkForm, extra=1, max_num=2)
+>>> formset = LimitedFavoriteDrinkFormSet()
+>>> for form in formset.forms:
+...     print form
+<tr><th><label for="id_form-0-name">Name:</label></th><td><input type="text" name="form-0-name" id="id_form-0-name" /></td></tr>
+
+# max_num with initial data
+
+# More initial forms than max_num will result in only the first max_num of
+# them to be displayed with no extra forms.
+
+>>> initial = [
+...     {'name': 'Gin Tonic'},
+...     {'name': 'Bloody Mary'},
+...     {'name': 'Jack and Coke'},
+... ]
+>>> LimitedFavoriteDrinkFormSet = formset_factory(FavoriteDrinkForm, extra=1, max_num=2)
+>>> formset = LimitedFavoriteDrinkFormSet(initial=initial)
+>>> for form in formset.forms:
+...     print form
+<tr><th><label for="id_form-0-name">Name:</label></th><td><input type="text" name="form-0-name" value="Gin Tonic" id="id_form-0-name" /></td></tr>
+<tr><th><label for="id_form-1-name">Name:</label></th><td><input type="text" name="form-1-name" value="Bloody Mary" id="id_form-1-name" /></td></tr>
+
+# One form from initial and extra=3 with max_num=2 should result in the one
+# initial form and one extra.
+
+>>> initial = [
+...     {'name': 'Gin Tonic'},
+... ]
+>>> LimitedFavoriteDrinkFormSet = formset_factory(FavoriteDrinkForm, extra=3, max_num=2)
+>>> formset = LimitedFavoriteDrinkFormSet(initial=initial)
+>>> for form in formset.forms:
+...     print form
+<tr><th><label for="id_form-0-name">Name:</label></th><td><input type="text" name="form-0-name" value="Gin Tonic" id="id_form-0-name" /></td></tr>
+<tr><th><label for="id_form-1-name">Name:</label></th><td><input type="text" name="form-1-name" id="id_form-1-name" /></td></tr>
+
 
 # Regression test for #6926 ##################################################