Fixed #31262 -- Added support for mappings on model fields and ChoiceField's choices.

docs/ref/forms/fields.txt

@@ -510,8 +510,9 @@ For each field, we describe the default widget used if you don't specify
 
     .. versionchanged:: 5.0
 
-        Support for using :ref:`enumeration types <field-choices-enum-types>`
-        directly in the ``choices`` was added.
+        Support for mappings and using
+        :ref:`enumeration types <field-choices-enum-types>` directly in
+        ``choices`` was added.
 
 ``DateField``
 -------------

docs/ref/forms/widgets.txt

@@ -58,11 +58,11 @@ widget on the field. In the following example, the
     from django import forms
 
     BIRTH_YEAR_CHOICES = ["1980", "1981", "1982"]
-    FAVORITE_COLORS_CHOICES = [
-        ("blue", "Blue"),
-        ("green", "Green"),
-        ("black", "Black"),
-    ]
+    FAVORITE_COLORS_CHOICES = {
+        "blue": "Blue",
+        "green": "Green",
+        "black": "Black",
+    }
 
 
     class SimpleForm(forms.Form):
@@ -95,7 +95,7 @@ example:
 .. code-block:: pycon
 
     >>> from django import forms
-    >>> CHOICES = [("1", "First"), ("2", "Second")]
+    >>> CHOICES = {"1": "First", "2": "Second"}
     >>> choice_field = forms.ChoiceField(widget=forms.RadioSelect, choices=CHOICES)
     >>> choice_field.choices
     [('1', 'First'), ('2', 'Second')]
@@ -458,9 +458,9 @@ foundation for custom widgets.
 
         class DateSelectorWidget(forms.MultiWidget):
             def __init__(self, attrs=None):
-                days = [(day, day) for day in range(1, 32)]
-                months = [(month, month) for month in range(1, 13)]
-                years = [(year, year) for year in [2018, 2019, 2020]]
+                days = {day: day for day in range(1, 32)}
+                months = {month: month for month in range(1, 13)}
+                years = {year: year for year in [2018, 2019, 2020]}
                 widgets = [
                     forms.Select(attrs=attrs, choices=days),
                     forms.Select(attrs=attrs, choices=months),