Document how to customize SplitPhoneNumberField fields

docs/reference.rst

@@ -168,6 +168,14 @@ A :class:`~django.forms.MultiValueField` that offers:
 - a ``<select … >`` element to choose the region, and
 - an ``<input type="tel" … >`` to enter the phone number.
 
+To customize each field, subclass
+:class:`~phonenumber_field.formfields.SplitPhoneNumberField` and override:
+
+- :func:`~phonenumber_field.formfields.SplitPhoneNumberField.prefix_field`
+  for the phone number prefix field,
+- :func:`~phonenumber_field.formfields.SplitPhoneNumberField.number_field`
+  for the phone number field.
+
 This widget uses an example phone number from the selected region for the
 ``invalid`` key in :attr:`~django.forms.Field.error_messages`, when the region
 choice is valid.
@@ -180,6 +188,8 @@ To customize the dynamic message, use
 .. autoclass:: phonenumber_field.formfields.SplitPhoneNumberField
 
    .. automethod:: __init__
+   .. automethod:: prefix_field
+   .. automethod:: number_field
    .. automethod:: invalid_error_message
 
 Usage

phonenumber_field/formfields.py

@@ -136,13 +136,19 @@ def __init__(self, *, initial=None, region=None, widget=None, **kwargs):
 
     def prefix_field(self):
         """
-        Customize the phone number prefix field.
+        Returns the default :class:`~django.forms.Field` for the phone
+        number prefix field.
+
+        Use this hook to set widget attributes or update the field definition.
         """
         return PrefixChoiceField()
 
     def number_field(self):
         """
-        Customize the phone number input field.
+        Returns the default :class:`~django.forms.Field` for the phone
+        number field.
+
+        Use this hook to set widget attributes or update the field definition.
         """
         number_field = CharField()
         number_field.widget.input_type = "tel"