[1.5.X] Added WizardView.file_storage exception message and docs

Thanks Danilo Bargen for the patch.

Backport of af7ea808d8 from master

django/contrib/formtools/wizard/storage/base.py

@@ -69,7 +69,9 @@ class BaseStorage(object):
         wizard_files = self.data[self.step_files_key].get(step, {})
 
         if wizard_files and not self.file_storage:
-            raise NoFileStorageConfigured
+            raise NoFileStorageConfigured(
+                    "You need to define 'file_storage' in your "
+                    "wizard view in order to handle file uploads.")
 
         files = {}
         for field, field_dict in six.iteritems(wizard_files):
@@ -81,7 +83,9 @@ class BaseStorage(object):
 
     def set_step_files(self, step, files):
         if files and not self.file_storage:
-            raise NoFileStorageConfigured
+            raise NoFileStorageConfigured(
+                    "You need to define 'file_storage' in your "
+                    "wizard view in order to handle file uploads.")
 
         if step not in self.data[self.step_files_key]:
             self.data[self.step_files_key][step] = {}

django/contrib/formtools/wizard/views.py

@@ -174,7 +174,9 @@ class WizardView(TemplateView):
             for field in six.itervalues(form.base_fields):
                 if (isinstance(field, forms.FileField) and
                         not hasattr(cls, 'file_storage')):
-                    raise NoFileStorageConfigured
+                    raise NoFileStorageConfigured(
+                            "You need to define 'file_storage' in your "
+                            "wizard view in order to handle file uploads.")
 
         # build the kwargs for the wizardview instances
         kwargs['form_list'] = init_form_list
@@ -436,8 +438,8 @@ class WizardView(TemplateView):
     def get_all_cleaned_data(self):
         """
         Returns a merged dictionary of all step cleaned_data dictionaries.
-        If a step contains a `FormSet`, the key will be prefixed with formset
+        If a step contains a `FormSet`, the key will be prefixed with
-        and contain a list of the formset cleaned_data dictionaries.
+        'formset-' and contain a list of the formset cleaned_data dictionaries.
         """
         cleaned_data = {}
         for form_key in self.get_form_list():
@@ -458,8 +460,8 @@ class WizardView(TemplateView):
     def get_cleaned_data_for_step(self, step):
         """
         Returns the cleaned data for a given `step`. Before returning the
-        cleaned data, the stored values are being revalidated through the
+        cleaned data, the stored values are revalidated through the form.
-        form. If the data doesn't validate, None will be returned.
+        If the data doesn't validate, None will be returned.
         """
         if step in self.form_list:
             form_obj = self.get_form(step=step,

docs/ref/contrib/formtools/form-wizard.txt

@@ -493,6 +493,21 @@ Advanced ``WizardView`` methods
             context = self.get_context_data(form=form, **kwargs)
             return self.render_to_response(context)
 
+.. method:: WizardView.get_cleaned_data_for_step(step)
+
+    This method returns the cleaned data for a given ``step``. Before returning
+    the cleaned data, the stored values are revalidated through the form. If
+    the data doesn't validate, ``None`` will be returned.
+
+.. method:: WizardView.get_all_cleaned_data()
+
+    This method returns a merged dictionary of all form steps' ``cleaned_data``
+    dictionaries. If a step contains a ``FormSet``, the key will be prefixed
+    with ``formset-`` and contain a list of the formset's ``cleaned_data``
+    dictionaries. Note that if two or more steps have a field with the same
+    name, the value for that field from the latest step will overwrite the
+    value from any earlier steps.
+
 Providing initial data for the forms
 ====================================
 
@@ -534,6 +549,16 @@ This storage will temporarily store the uploaded files for the wizard. The
 :attr:`file_storage` attribute should be a
 :class:`~django.core.files.storage.Storage` subclass.
 
+Django provides a built-in storage class (see :ref:`the built-in filesystem
+storage class <builtin-fs-storage>`)::
+
+    from django.conf import settings
+    from django.core.files.storage import FileSystemStorage
+
+    class CustomWizardView(WizardView):
+        ...
+        file_storage = FileSystemStorage(location=os.path.join(settings.MEDIA_ROOT, 'photos'))
+
 .. warning::
 
     Please remember to take care of removing old files as the

docs/topics/files.txt

@@ -139,6 +139,8 @@ useful -- you can use the global default storage system::
 
 See :doc:`/ref/files/storage` for the file storage API.
 
+.. _builtin-fs-storage:
+
 The built-in filesystem storage class
 -------------------------------------