Remove deprecated NullBooleanField.

docs/api-guide/fields.md

@@ -159,14 +159,6 @@ Corresponds to `django.db.models.fields.BooleanField`.
 
 **Signature:** `BooleanField()`
 
-## NullBooleanField
-
-A boolean representation that also accepts `None` as a valid value.
-
-Corresponds to `django.db.models.fields.NullBooleanField`.
-
-**Signature:** `NullBooleanField()`
-
 ---
 
 # String fields

rest_framework/fields.py

@@ -5,7 +5,6 @@ import functools
 import inspect
 import re
 import uuid
-import warnings
 from collections import OrderedDict
 from collections.abc import Mapping
 
@@ -30,7 +29,7 @@ from django.utils.ipv6 import clean_ipv6_address
 from django.utils.translation import gettext_lazy as _
 from pytz.exceptions import InvalidTimeError
 
-from rest_framework import ISO_8601, RemovedInDRF314Warning
+from rest_framework import ISO_8601
 from rest_framework.exceptions import ErrorDetail, ValidationError
 from rest_framework.settings import api_settings
 from rest_framework.utils import html, humanize_datetime, json, representation
@@ -712,23 +711,6 @@ class BooleanField(Field):
         return bool(value)
 
 
-class NullBooleanField(BooleanField):
-    initial = None
-
-    def __init__(self, **kwargs):
-        warnings.warn(
-            "The `NullBooleanField` is deprecated and will be removed starting "
-            "with 3.14. Instead use the `BooleanField` field and set "
-            "`allow_null=True` which does the same thing.",
-            RemovedInDRF314Warning, stacklevel=2
-        )
-
-        assert 'allow_null' not in kwargs, '`allow_null` is not a valid option.'
-        kwargs['allow_null'] = True
-
-        super().__init__(**kwargs)
-
-
 # String types...
 
 class CharField(Field):

rest_framework/metadata.py

@@ -36,7 +36,6 @@ class SimpleMetadata(BaseMetadata):
     label_lookup = ClassLookupDict({
         serializers.Field: 'field',
         serializers.BooleanField: 'boolean',
-        serializers.NullBooleanField: 'boolean',
         serializers.CharField: 'string',
         serializers.UUIDField: 'string',
         serializers.URLField: 'url',

rest_framework/serializers.py

@@ -52,7 +52,7 @@ from rest_framework.fields import (  # NOQA # isort:skip
     BooleanField, CharField, ChoiceField, DateField, DateTimeField, DecimalField,
     DictField, DurationField, EmailField, Field, FileField, FilePathField, FloatField,
     HiddenField, HStoreField, IPAddressField, ImageField, IntegerField, JSONField,
-    ListField, ModelField, MultipleChoiceField, NullBooleanField, ReadOnlyField,
+    ListField, ModelField, MultipleChoiceField, ReadOnlyField,
     RegexField, SerializerMethodField, SlugField, TimeField, URLField, UUIDField,
 )
 from rest_framework.relations import (  # NOQA # isort:skip

tests/test_fields.py

@@ -679,9 +679,9 @@ class TestBooleanField(FieldValues):
             assert exc_info.value.detail == expected
 
 
-class TestNullBooleanField(TestBooleanField):
+class TestNullableBooleanField(TestBooleanField):
     """
-    Valid and invalid values for `NullBooleanField`.
+    Valid and invalid values for `BooleanField` when `allow_null=True`.
     """
     valid_inputs = {
         'true': True,
@@ -706,16 +706,6 @@ class TestNullBooleanField(TestBooleanField):
     field = serializers.BooleanField(allow_null=True)
 
 
-class TestNullableBooleanField(TestNullBooleanField):
-    """
-    Valid and invalid values for `BooleanField` when `allow_null=True`.
-    """
-
-    @property
-    def field(self):
-        return serializers.BooleanField(allow_null=True)
-
-
 # String types...
 
 class TestCharField(FieldValues):