Fixed #25078 -- Added support for disabled form fields

Thanks Keryn Knight and Tim Graham for the reviews.

django/forms/fields.py

@@ -70,7 +70,7 @@ class Field(six.with_metaclass(RenameFieldMethods, object)):
 
     def __init__(self, required=True, widget=None, label=None, initial=None,
                  help_text='', error_messages=None, show_hidden_initial=False,
-                 validators=[], localize=False, label_suffix=None):
+                 validators=[], localize=False, disabled=False, label_suffix=None):
         # required -- Boolean that specifies whether the field is required.
         #             True by default.
         # widget -- A Widget class, or instance of a Widget class, that should
@@ -90,11 +90,14 @@ class Field(six.with_metaclass(RenameFieldMethods, object)):
         #                        hidden widget with initial value after widget.
         # validators -- List of additional validators to use
         # localize -- Boolean that specifies if the field should be localized.
+        # disabled -- Boolean that specifies whether the field is disabled, that
+        #             is its widget is shown in the form but not editable.
         # label_suffix -- Suffix to be added to the label. Overrides
         #                 form's label_suffix.
         self.required, self.label, self.initial = required, label, initial
         self.show_hidden_initial = show_hidden_initial
         self.help_text = help_text
+        self.disabled = disabled
         self.label_suffix = label_suffix
         widget = widget or self.widget
         if isinstance(widget, type):

django/forms/forms.py

@@ -386,7 +386,10 @@ class BaseForm(object):
             # value_from_datadict() gets the data from the data dictionaries.
             # Each widget type knows how to retrieve its own data, because some
             # widgets split data over several HTML fields.
-            value = field.widget.value_from_datadict(self.data, self.files, self.add_prefix(name))
+            if field.disabled:
+                value = self.initial.get(name, field.initial)
+            else:
+                value = field.widget.value_from_datadict(self.data, self.files, self.add_prefix(name))
             try:
                 if isinstance(field, FileField):
                     initial = self.initial.get(name, field.initial)
@@ -567,6 +570,8 @@ class BoundField(object):
             widget.is_localized = True
 
         attrs = attrs or {}
+        if self.field.disabled:
+            attrs['disabled'] = True
         auto_id = self.auto_id
         if auto_id and 'id' not in attrs and 'id' not in widget.attrs:
             if not only_initial:

docs/ref/forms/fields.txt

@@ -299,6 +299,17 @@ as the rendered output.
 See the :ref:`format localization <format-localization>` documentation for
 more information.
 
+``disabled``
+~~~~~~~~~~~~
+
+.. attribute:: Field.disabled
+
+.. versionadded:: 1.9
+
+The ``disabled`` boolean argument, when set to ``True``, disables a form field
+using the ``disabled`` HTML attribute so that it won't be editable by users.
+Even if a user tampers with the field's value submitted to the server, it will
+be ignored in favor of the value from the form's initial data.
 
 Checking if the field data has changed
 --------------------------------------

docs/releases/1.9.txt

@@ -313,6 +313,9 @@ Forms
   and trailing whitespace.  As this defaults to ``True`` this is different
   behavior from previous releases.
 
+* Form fields now support the :attr:`~django.forms.Field.disabled` argument,
+  allowing the field widget to be displayed disabled by browsers.
+
 Generic Views
 ^^^^^^^^^^^^^
 

tests/forms_tests/tests/test_fields.py

@@ -176,6 +176,10 @@ class FieldsTests(SimpleTestCase):
         self.assertEqual(f.clean(' 1'), ' 1')
         self.assertEqual(f.clean('1 '), '1 ')
 
+    def test_charfield_disabled(self):
+        f = CharField(disabled=True)
+        self.assertWidgetRendersTo(f, '<input type="text" name="f" id="id_f" disabled />')
+
     # IntegerField ################################################################
 
     def test_integerfield_1(self):
@@ -1076,6 +1080,12 @@ class FieldsTests(SimpleTestCase):
         form = ChoiceFieldForm()
         self.assertEqual([('P', 'Paul')], list(form.fields['choicefield'].choices))
 
+    def test_choicefield_disabled(self):
+        f = ChoiceField(choices=[('J', 'John'), ('P', 'Paul')], disabled=True)
+        self.assertWidgetRendersTo(f,
+            '<select id="id_f" name="f" disabled><option value="J">John</option>'
+            '<option value="P">Paul</option></select>')
+
     # TypedChoiceField ############################################################
     # TypedChoiceField is just like ChoiceField, except that coerced types will
     # be returned:

tests/forms_tests/tests/test_forms.py

@@ -501,6 +501,37 @@ class FormsTestCase(SimpleTestCase):
 <option value="P" selected="selected">Paul McCartney</option>
 </select>""")
 
+    def test_form_with_disabled_fields(self):
+        class PersonForm(Form):
+            name = CharField()
+            birthday = DateField(disabled=True)
+
+        class PersonFormFieldInitial(Form):
+            name = CharField()
+            birthday = DateField(disabled=True, initial=datetime.date(1974, 8, 16))
+
+        # Disabled fields are generally not transmitted by user agents.
+        # The value from the form's initial data is used.
+        f1 = PersonForm({'name': 'John Doe'}, initial={'birthday': datetime.date(1974, 8, 16)})
+        f2 = PersonFormFieldInitial({'name': 'John Doe'})
+        for form in (f1, f2):
+            self.assertTrue(form.is_valid())
+            self.assertEqual(
+                form.cleaned_data,
+                {'birthday': datetime.date(1974, 8, 16), 'name': 'John Doe'}
+            )
+
+        # Values provided in the form's data are ignored.
+        data = {'name': 'John Doe', 'birthday': '1984-11-10'}
+        f1 = PersonForm(data, initial={'birthday': datetime.date(1974, 8, 16)})
+        f2 = PersonFormFieldInitial(data)
+        for form in (f1, f2):
+            self.assertTrue(form.is_valid())
+            self.assertEqual(
+                form.cleaned_data,
+                {'birthday': datetime.date(1974, 8, 16), 'name': 'John Doe'}
+            )
+
     def test_hidden_data(self):
         class SongForm(Form):
             name = CharField()