From eba9a9b7f72995206af867600d6685b5405f172a Mon Sep 17 00:00:00 2001
From: David Smith <smithdc@gmail.com>
Date: Sat, 6 Nov 2021 06:50:29 +0000
Subject: [PATCH] Refs #32338 -- Added Boundfield.legend_tag().

---
 django/forms/boundfield.py                    |  15 ++-
 django/forms/jinja2/django/forms/label.html   |   2 +-
 .../forms/templates/django/forms/label.html   |   2 +-
 docs/ref/forms/api.txt                        |  36 ++++--
 docs/releases/4.1.txt                         |   4 +-
 .../templates/forms_tests/legend_test.html    |   7 ++
 tests/forms_tests/tests/test_forms.py         | 117 ++++++++++++++++--
 tests/forms_tests/tests/test_i18n.py          |   8 ++
 .../test_checkboxselectmultiple.py            |   1 +
 tests/model_forms/tests.py                    |  12 ++
 tests/model_formsets/tests.py                 |   8 ++
 11 files changed, 188 insertions(+), 24 deletions(-)
 create mode 100644 tests/forms_tests/templates/forms_tests/legend_test.html

diff --git a/django/forms/boundfield.py b/django/forms/boundfield.py
index 5bbfcbe41c..62d1823d57 100644
--- a/django/forms/boundfield.py
+++ b/django/forms/boundfield.py
@@ -145,7 +145,7 @@ class BoundField:
             initial_value = self.initial
         return field.has_changed(initial_value, self.data)
 
-    def label_tag(self, contents=None, attrs=None, label_suffix=None):
+    def label_tag(self, contents=None, attrs=None, label_suffix=None, tag=None):
         """
         Wrap the given contents in a <label>, if the field has an ID attribute.
         contents should be mark_safe'd to avoid HTML escaping. If contents
@@ -181,9 +181,22 @@ class BoundField:
             'label': contents,
             'attrs': attrs,
             'use_tag': bool(id_),
+            'tag': tag or 'label',
         }
         return self.form.render(self.form.template_name_label, context)
 
+    def legend_tag(self, contents=None, attrs=None, label_suffix=None):
+        """
+        Wrap the given contents in a <legend>, if the field has an ID
+        attribute. Contents should be mark_safe'd to avoid HTML escaping. If
+        contents aren't given, use the field's HTML-escaped label.
+
+        If attrs are given, use them as HTML attributes on the <legend> tag.
+
+        label_suffix overrides the form's label_suffix.
+        """
+        return self.label_tag(contents, attrs, label_suffix, tag='legend')
+
     def css_classes(self, extra_classes=None):
         """
         Return a string of space-separated CSS classes for this field.
diff --git a/django/forms/jinja2/django/forms/label.html b/django/forms/jinja2/django/forms/label.html
index 7ad5257a71..6ce3885f79 100644
--- a/django/forms/jinja2/django/forms/label.html
+++ b/django/forms/jinja2/django/forms/label.html
@@ -1 +1 @@
-{% if use_tag %}<label{% if attrs %}{% include 'django/forms/attrs.html' %}{% endif %}>{{ label }}</label>{% else %}{{ label }}{% endif %}
+{% if use_tag %}<{{ tag }}{% if attrs %}{% include 'django/forms/attrs.html' %}{% endif %}>{{ label }}</{{ tag }}>{% else %}{{ label }}{% endif %}
diff --git a/django/forms/templates/django/forms/label.html b/django/forms/templates/django/forms/label.html
index eb2a9f7973..0eba630e82 100644
--- a/django/forms/templates/django/forms/label.html
+++ b/django/forms/templates/django/forms/label.html
@@ -1 +1 @@
-{% if use_tag %}<label{% include 'django/forms/attrs.html' %}>{{ label }}</label>{% else %}{{ label }}{% endif %}
+{% if use_tag %}<{{ tag }}{% include 'django/forms/attrs.html' %}>{{ label }}</{{ tag }}>{% else %}{{ label }}{% endif %}
diff --git a/docs/ref/forms/api.txt b/docs/ref/forms/api.txt
index d80d9ea224..e092a2f59e 100644
--- a/docs/ref/forms/api.txt
+++ b/docs/ref/forms/api.txt
@@ -542,9 +542,9 @@ default template, see also :ref:`overriding-built-in-form-templates`.
 .. attribute:: Form.template_name_label
 
 The template used to render a field's ``<label>``, used when calling
-:meth:`BoundField.label_tag`. Can be changed per form by overriding this
-attribute or more generally by overriding the default template, see also
-:ref:`overriding-built-in-form-templates`.
+:meth:`BoundField.label_tag`/:meth:`~BoundField.legend_tag`. Can be changed per
+form by overriding this attribute or more generally by overriding the default
+template, see also :ref:`overriding-built-in-form-templates`.
 
 ``as_p()``
 ----------
@@ -672,8 +672,12 @@ classes, as needed. The HTML will look something like::
     <tr><th><label for="id_cc_myself">Cc myself:<label> ...
     >>> f['subject'].label_tag()
     <label class="required" for="id_subject">Subject:</label>
+    >>> f['subject'].legend_tag()
+    <legend class="required" for="id_subject">Subject:</legend>
     >>> f['subject'].label_tag(attrs={'class': 'foo'})
     <label for="id_subject" class="foo required">Subject:</label>
+    >>> f['subject'].legend_tag(attrs={'class': 'foo'})
+    <legend for="id_subject" class="foo required">Subject:</legend>
 
 .. _ref-forms-api-configuring-label:
 
@@ -797,7 +801,8 @@ Fields can also define their own :attr:`~django.forms.Field.label_suffix`.
 This will take precedence over :attr:`Form.label_suffix
 <django.forms.Form.label_suffix>`. The suffix can also be overridden at runtime
 using the ``label_suffix`` parameter to
-:meth:`~django.forms.BoundField.label_tag`.
+:meth:`~django.forms.BoundField.label_tag`/
+:meth:`~django.forms.BoundField.legend_tag`.
 
 .. attribute:: Form.use_required_attribute
 
@@ -1092,7 +1097,8 @@ Attributes of ``BoundField``
 
     Use this property to render the ID of this field. For example, if you are
     manually constructing a ``<label>`` in your template (despite the fact that
-    :meth:`~BoundField.label_tag` will do this for you):
+    :meth:`~BoundField.label_tag`/:meth:`~BoundField.legend_tag` will do this
+    for you):
 
     .. code-block:: html+django
 
@@ -1142,7 +1148,7 @@ Attributes of ``BoundField``
 .. attribute:: BoundField.label
 
     The :attr:`~django.forms.Field.label` of the field. This is used in
-    :meth:`~BoundField.label_tag`.
+    :meth:`~BoundField.label_tag`/:meth:`~BoundField.legend_tag`.
 
 .. attribute:: BoundField.name
 
@@ -1208,7 +1214,7 @@ Methods of ``BoundField``
         >>> f['message'].css_classes('foo bar')
         'foo bar required'
 
-.. method:: BoundField.label_tag(contents=None, attrs=None, label_suffix=None)
+.. method:: BoundField.label_tag(contents=None, attrs=None, label_suffix=None, tag=None)
 
     Renders a label tag for the form field using the template specified by
     :attr:`.Form.template_name_label`.
@@ -1225,7 +1231,8 @@ Methods of ``BoundField``
       field's widget ``attrs`` or :attr:`BoundField.auto_id`. Additional
       attributes can be provided by the ``attrs`` argument.
     * ``use_tag``: A boolean which is ``True`` if the label has an ``id``.
-      If ``False`` the default template omits the ``<label>`` tag.
+      If ``False`` the default template omits the ``tag``.
+    * ``tag``: An optional string to customize the tag, defaults to ``label``.
 
     .. tip::
 
@@ -1249,6 +1256,19 @@ Methods of ``BoundField``
 
         The label is now rendered using the template engine.
 
+    .. versionchanged:: 4.1
+
+        The ``tag`` argument was added.
+
+.. method:: BoundField.legend_tag(contents=None, attrs=None, label_suffix=None)
+
+    .. versionadded:: 4.1
+
+    Calls :meth:`.label_tag` with ``tag='legend'`` to render the label with
+    ``<legend>`` tags. This is useful when rendering radio and multiple
+    checkbox widgets where ``<legend>`` may be more appropriate than a
+    ``<label>``.
+
 .. method:: BoundField.value()
 
     Use this method to render the raw value of this field as it would be rendered
diff --git a/docs/releases/4.1.txt b/docs/releases/4.1.txt
index c55e638695..3fdd7f53c6 100644
--- a/docs/releases/4.1.txt
+++ b/docs/releases/4.1.txt
@@ -177,7 +177,9 @@ File Uploads
 Forms
 ~~~~~
 
-* ...
+* The new :meth:`~django.forms.BoundField.legend_tag` allows rendering field
+  labels in ``<legend>`` tags via the new ``tag`` argument of
+  :meth:`~django.forms.BoundField.label_tag`.
 
 Generic Views
 ~~~~~~~~~~~~~
diff --git a/tests/forms_tests/templates/forms_tests/legend_test.html b/tests/forms_tests/templates/forms_tests/legend_test.html
new file mode 100644
index 0000000000..436485e794
--- /dev/null
+++ b/tests/forms_tests/templates/forms_tests/legend_test.html
@@ -0,0 +1,7 @@
+{% for field in form %}
+  {% if field.widget_type == 'radioselect' %}
+    {{ field.legend_tag }}
+  {% else %}
+    {{ field.label_tag }}
+  {% endif %}
+{% endfor %}
diff --git a/tests/forms_tests/tests/test_forms.py b/tests/forms_tests/tests/test_forms.py
index c478a71699..7e0bdeeb77 100644
--- a/tests/forms_tests/tests/test_forms.py
+++ b/tests/forms_tests/tests/test_forms.py
@@ -2728,7 +2728,8 @@ Password: <input type="password" name="password" required>
 
     def test_label_has_required_css_class(self):
         """
-        #17922 - required_css_class is added to the label_tag() of required fields.
+        required_css_class is added to label_tag() and legend_tag() of required
+        fields.
         """
         class SomeForm(Form):
             required_css_class = 'required'
@@ -2737,11 +2738,23 @@ Password: <input type="password" name="password" required>
 
         f = SomeForm({'field': 'test'})
         self.assertHTMLEqual(f['field'].label_tag(), '<label for="id_field" class="required">Field:</label>')
+        self.assertHTMLEqual(
+            f['field'].legend_tag(),
+            '<legend for="id_field" class="required">Field:</legend>',
+        )
         self.assertHTMLEqual(
             f['field'].label_tag(attrs={'class': 'foo'}),
             '<label for="id_field" class="foo required">Field:</label>'
         )
+        self.assertHTMLEqual(
+            f['field'].legend_tag(attrs={'class': 'foo'}),
+            '<legend for="id_field" class="foo required">Field:</legend>'
+        )
         self.assertHTMLEqual(f['field2'].label_tag(), '<label for="id_field2">Field2:</label>')
+        self.assertHTMLEqual(
+            f['field2'].legend_tag(),
+            '<legend for="id_field2">Field2:</legend>',
+        )
 
     def test_label_split_datetime_not_displayed(self):
         class EventForm(Form):
@@ -2964,34 +2977,47 @@ Password: <input type="password" name="password" required>
 
         testcases = [  # (args, kwargs, expected)
             # without anything: just print the <label>
-            ((), {}, '<label for="id_field">Field:</label>'),
+            ((), {}, '<%(tag)s for="id_field">Field:</%(tag)s>'),
 
             # passing just one argument: overrides the field's label
-            (('custom',), {}, '<label for="id_field">custom:</label>'),
+            (('custom',), {}, '<%(tag)s for="id_field">custom:</%(tag)s>'),
 
             # the overridden label is escaped
-            (('custom&',), {}, '<label for="id_field">custom&amp;:</label>'),
-            ((mark_safe('custom&'),), {}, '<label for="id_field">custom&:</label>'),
+            (('custom&',), {}, '<%(tag)s for="id_field">custom&amp;:</%(tag)s>'),
+            ((mark_safe('custom&'),), {}, '<%(tag)s for="id_field">custom&:</%(tag)s>'),
 
             # Passing attrs to add extra attributes on the <label>
-            ((), {'attrs': {'class': 'pretty'}}, '<label for="id_field" class="pretty">Field:</label>')
+            (
+                (),
+                {'attrs': {'class': 'pretty'}},
+                '<%(tag)s for="id_field" class="pretty">Field:</%(tag)s>',
+            ),
         ]
 
         for args, kwargs, expected in testcases:
             with self.subTest(args=args, kwargs=kwargs):
-                self.assertHTMLEqual(boundfield.label_tag(*args, **kwargs), expected)
+                self.assertHTMLEqual(
+                    boundfield.label_tag(*args, **kwargs),
+                    expected % {'tag': 'label'},
+                )
+                self.assertHTMLEqual(
+                    boundfield.legend_tag(*args, **kwargs),
+                    expected % {'tag': 'legend'},
+                )
 
     def test_boundfield_label_tag_no_id(self):
         """
-        If a widget has no id, label_tag just returns the text with no
-        surrounding <label>.
+        If a widget has no id, label_tag() and legend_tag() return the text
+        with no surrounding <label>.
         """
         class SomeForm(Form):
             field = CharField()
         boundfield = SomeForm(auto_id='')['field']
 
         self.assertHTMLEqual(boundfield.label_tag(), 'Field:')
+        self.assertHTMLEqual(boundfield.legend_tag(), 'Field:')
         self.assertHTMLEqual(boundfield.label_tag('Custom&'), 'Custom&amp;:')
+        self.assertHTMLEqual(boundfield.legend_tag('Custom&'), 'Custom&amp;:')
 
     def test_boundfield_label_tag_custom_widget_id_for_label(self):
         class CustomIdForLabelTextInput(TextInput):
@@ -3008,7 +3034,12 @@ Password: <input type="password" name="password" required>
 
         form = SomeForm()
         self.assertHTMLEqual(form['custom'].label_tag(), '<label for="custom_id_custom">Custom:</label>')
+        self.assertHTMLEqual(
+            form['custom'].legend_tag(),
+            '<legend for="custom_id_custom">Custom:</legend>',
+        )
         self.assertHTMLEqual(form['empty'].label_tag(), '<label>Empty:</label>')
+        self.assertHTMLEqual(form['empty'].legend_tag(), '<legend>Empty:</legend>')
 
     def test_boundfield_empty_label(self):
         class SomeForm(Form):
@@ -3016,6 +3047,10 @@ Password: <input type="password" name="password" required>
         boundfield = SomeForm()['field']
 
         self.assertHTMLEqual(boundfield.label_tag(), '<label for="id_field"></label>')
+        self.assertHTMLEqual(
+            boundfield.legend_tag(),
+            '<legend for="id_field"></legend>',
+        )
 
     def test_boundfield_id_for_label(self):
         class SomeForm(Form):
@@ -3069,7 +3104,7 @@ Password: <input type="password" name="password" required>
         self.assertEqual(field.css_classes(extra_classes='test'), 'test')
         self.assertEqual(field.css_classes(extra_classes='test test'), 'test')
 
-    def test_label_tag_override(self):
+    def test_label_suffix_override(self):
         """
         BoundField label_suffix (if provided) overrides Form label_suffix
         """
@@ -3078,6 +3113,10 @@ Password: <input type="password" name="password" required>
         boundfield = SomeForm(label_suffix='!')['field']
 
         self.assertHTMLEqual(boundfield.label_tag(label_suffix='$'), '<label for="id_field">Field$</label>')
+        self.assertHTMLEqual(
+            boundfield.legend_tag(label_suffix='$'),
+            '<legend for="id_field">Field$</legend>',
+        )
 
     def test_error_dict(self):
         class MyForm(Form):
@@ -3526,9 +3565,10 @@ Password: <input type="password" name="password" required>
     def test_label_does_not_include_new_line(self):
         form = Person()
         field = form['first_name']
+        self.assertEqual(field.label_tag(), '<label for="id_first_name">First name:</label>')
         self.assertEqual(
-            field.label_tag(),
-            '<label for="id_first_name">First name:</label>',
+            field.legend_tag(),
+            '<legend for="id_first_name">First name:</legend>',
         )
 
     @override_settings(USE_THOUSAND_SEPARATOR=True)
@@ -3539,6 +3579,10 @@ Password: <input type="password" name="password" required>
             field.label_tag(attrs={'number': 9999}),
             '<label number="9999" for="id_first_name">First name:</label>',
         )
+        self.assertHTMLEqual(
+            field.legend_tag(attrs={'number': 9999}),
+            '<legend number="9999" for="id_first_name">First name:</legend>',
+        )
 
 
 @jinja2_tests
@@ -3747,6 +3791,43 @@ class TemplateTests(SimpleTestCase):
             '<input type="submit" required>'
             '</form>',
         )
+        # Use form.[field].legend_tag to output a field's label with a <legend>
+        # tag wrapped around it, but *only* if the given field has an "id"
+        # attribute. Recall from above that passing the "auto_id" argument to a
+        # Form gives each field an "id" attribute.
+        t = Template(
+            '<form>'
+            '<p>{{ form.username.legend_tag }} {{ form.username }}</p>'
+            '<p>{{ form.password1.legend_tag }} {{ form.password1 }}</p>'
+            '<p>{{ form.password2.legend_tag }} {{ form.password2 }}</p>'
+            '<input type="submit" required>'
+            '</form>'
+        )
+        f = UserRegistration(auto_id=False)
+        self.assertHTMLEqual(
+            t.render(Context({'form': f})),
+            '<form>'
+            '<p>Username: '
+            '<input type="text" name="username" maxlength="10" required></p>'
+            '<p>Password1: <input type="password" name="password1" required></p>'
+            '<p>Password2: <input type="password" name="password2" required></p>'
+            '<input type="submit" required>'
+            '</form>',
+        )
+        f = UserRegistration(auto_id='id_%s')
+        self.assertHTMLEqual(
+            t.render(Context({'form': f})),
+            '<form>'
+            '<p><legend for="id_username">Username:</legend>'
+            '<input id="id_username" type="text" name="username" maxlength="10" '
+            'required></p>'
+            '<p><legend for="id_password1">Password1:</legend>'
+            '<input type="password" name="password1" id="id_password1" required></p>'
+            '<p><legend for="id_password2">Password2:</legend>'
+            '<input type="password" name="password2" id="id_password2" required></p>'
+            '<input type="submit" required>'
+            '</form>',
+        )
         # Use form.[field].help_text to output a field's help text. If the
         # given field does not have help text, nothing will be output.
         t = Template(
@@ -3965,3 +4046,15 @@ class OverrideTests(SimpleTestCase):
             self.assertInHTML('<th>1</th>', f.render())
         except RecursionError:
             self.fail('Cyclic reference in BoundField.render().')
+
+    def test_legend_tag(self):
+        class CustomFrameworkForm(FrameworkForm):
+            template_name = 'forms_tests/legend_test.html'
+            required_css_class = 'required'
+
+        f = CustomFrameworkForm()
+        self.assertHTMLEqual(
+            str(f),
+            '<label for="id_name" class="required">Name:</label>'
+            '<legend class="required">Language:</legend>',
+        )
diff --git a/tests/forms_tests/tests/test_i18n.py b/tests/forms_tests/tests/test_i18n.py
index 67aafa0527..29967b2cb7 100644
--- a/tests/forms_tests/tests/test_i18n.py
+++ b/tests/forms_tests/tests/test_i18n.py
@@ -44,7 +44,15 @@ class FormsI18nTests(SimpleTestCase):
 
         f = SomeForm()
         self.assertHTMLEqual(f['field_1'].label_tag(), '<label for="id_field_1">field_1:</label>')
+        self.assertHTMLEqual(
+            f['field_1'].legend_tag(),
+            '<legend for="id_field_1">field_1:</legend>',
+        )
         self.assertHTMLEqual(f['field_2'].label_tag(), '<label for="field_2_id">field_2:</label>')
+        self.assertHTMLEqual(
+            f['field_2'].legend_tag(),
+            '<legend for="field_2_id">field_2:</legend>',
+        )
 
     def test_non_ascii_choices(self):
         class SomeForm(Form):
diff --git a/tests/forms_tests/widget_tests/test_checkboxselectmultiple.py b/tests/forms_tests/widget_tests/test_checkboxselectmultiple.py
index e831038e02..65025ed748 100644
--- a/tests/forms_tests/widget_tests/test_checkboxselectmultiple.py
+++ b/tests/forms_tests/widget_tests/test_checkboxselectmultiple.py
@@ -185,3 +185,4 @@ class CheckboxSelectMultipleTest(WidgetTest):
         bound_field = TestForm()['f']
         self.assertEqual(bound_field.field.widget.id_for_label('id'), '')
         self.assertEqual(bound_field.label_tag(), '<label>F:</label>')
+        self.assertEqual(bound_field.legend_tag(), '<legend>F:</legend>')
diff --git a/tests/model_forms/tests.py b/tests/model_forms/tests.py
index 7907aa1c3d..0307569c12 100644
--- a/tests/model_forms/tests.py
+++ b/tests/model_forms/tests.py
@@ -830,6 +830,18 @@ class TestFieldOverridesByFormMeta(SimpleTestCase):
             str(form['slug'].label_tag()),
             '<label for="id_slug">Slug:</label>',
         )
+        self.assertHTMLEqual(
+            form['name'].legend_tag(),
+            '<legend for="id_name">Title:</legend>',
+        )
+        self.assertHTMLEqual(
+            form['url'].legend_tag(),
+            '<legend for="id_url">The URL:</legend>',
+        )
+        self.assertHTMLEqual(
+            form['slug'].legend_tag(),
+            '<legend for="id_slug">Slug:</legend>',
+        )
 
     def test_help_text_overrides(self):
         form = FieldOverridesByFormMetaForm()
diff --git a/tests/model_formsets/tests.py b/tests/model_formsets/tests.py
index 49e7705c2f..bb1a8a8a5e 100644
--- a/tests/model_formsets/tests.py
+++ b/tests/model_formsets/tests.py
@@ -1801,6 +1801,10 @@ class TestModelFormsetOverridesTroughFormMeta(TestCase):
         })
         form = BookFormSet.form()
         self.assertHTMLEqual(form['title'].label_tag(), '<label for="id_title">Name:</label>')
+        self.assertHTMLEqual(
+            form['title'].legend_tag(),
+            '<legend for="id_title">Name:</legend>',
+        )
 
     def test_inlineformset_factory_labels_overrides(self):
         BookFormSet = inlineformset_factory(Author, Book, fields="__all__", labels={
@@ -1808,6 +1812,10 @@ class TestModelFormsetOverridesTroughFormMeta(TestCase):
         })
         form = BookFormSet.form()
         self.assertHTMLEqual(form['title'].label_tag(), '<label for="id_title">Name:</label>')
+        self.assertHTMLEqual(
+            form['title'].legend_tag(),
+            '<legend for="id_title">Name:</legend>',
+        )
 
     def test_modelformset_factory_help_text_overrides(self):
         BookFormSet = modelformset_factory(Book, fields="__all__", help_texts={