add mypy setup to tox.ini

mypy.ini

@@ -0,0 +1,2 @@
+[mypy]
+ignore_missing_imports = True

requirements/requirements-mypy.txt

@@ -0,0 +1 @@
+mypy==0.730

rest_framework/compat.py

@@ -117,14 +117,14 @@ except ImportError:
 try:
     import yaml
 except ImportError:
-    yaml = None
+    yaml = None  # type: ignore
 
 
 # requests is optional
 try:
     import requests
 except ImportError:
-    requests = None
+    requests = None  # type: ignore
 
 
 # PATCH method is not implemented by Django
@@ -156,7 +156,7 @@ try:
         md_filter_add_syntax_highlight(md)
         return md.convert(text)
 except ImportError:
-    apply_markdown = None
+    apply_markdown = None  # type: ignore
     markdown = None
 
 

rest_framework/fields.py

@@ -7,6 +7,7 @@ import re
 import uuid
 from collections import OrderedDict
 from collections.abc import Mapping
+from typing import Callable, List, Any, Optional, Dict
 
 from django.conf import settings
 from django.core.exceptions import ObjectDoesNotExist
@@ -302,9 +303,9 @@ class Field:
         'required': _('This field is required.'),
         'null': _('This field may not be null.')
     }
-    default_validators = []
-    default_empty_html = empty
-    initial = None
+    default_validators = []  # type: List[Callable[[Any], None]]
+    default_empty_html = empty  # type: Optional[Any]
+    initial = None  # type: Optional[Any]
 
     def __init__(self, read_only=False, write_only=False,
                  required=None, default=empty, initial=empty, source=None,
@@ -1456,7 +1457,7 @@ class MultipleChoiceField(ChoiceField):
         'not_a_list': _('Expected a list of items but got type "{input_type}".'),
         'empty': _('This selection may not be empty.')
     }
-    default_empty_html = []
+    default_empty_html = []  # type: List[Any]
 
     def __init__(self, *args, **kwargs):
         self.allow_empty = kwargs.pop('allow_empty', True)
@@ -1597,7 +1598,7 @@ class _UnvalidatedField(Field):
 
 class ListField(Field):
     child = _UnvalidatedField()
-    initial = []
+    initial = []  # type: List[Any]
     default_error_messages = {
         'not_a_list': _('Expected a list of items but got type "{input_type}".'),
         'empty': _('This list may not be empty.'),
@@ -1675,8 +1676,8 @@ class ListField(Field):
 
 
 class DictField(Field):
-    child = _UnvalidatedField()
-    initial = {}
+    child = _UnvalidatedField()  # type: Field
+    initial = {}  # type: Dict[str, Any]
     default_error_messages = {
         'not_a_dict': _('Expected a dictionary of items but got type "{input_type}".'),
         'empty': _('This dictionary may not be empty.'),

rest_framework/parsers.py

@@ -5,6 +5,7 @@ They give us a generic way of being able to handle various media types
 on the request, such as form content or json encoded data.
 """
 import codecs
+from typing import Optional
 from urllib import parse
 
 from django.conf import settings
@@ -33,7 +34,7 @@ class BaseParser:
     All parsers should extend `BaseParser`, specifying a `media_type`
     attribute, and overriding the `.parse()` method.
     """
-    media_type = None
+    media_type = None  # type: Optional[str]
 
     def parse(self, stream, media_type=None, parser_context=None):
         """

rest_framework/relations.py

@@ -1,5 +1,6 @@
 import sys
 from collections import OrderedDict
+from typing import List, Any
 from urllib import parse
 
 from django.core.exceptions import ImproperlyConfigured, ObjectDoesNotExist
@@ -472,8 +473,8 @@ class ManyRelatedField(Field):
     You shouldn't generally need to be using this class directly yourself,
     and should instead simply set 'many=True' on the relationship.
     """
-    initial = []
-    default_empty_html = []
+    initial = []  # type: List[Any]
+    default_empty_html = []  # type: List[Any]
     default_error_messages = {
         'not_a_list': _('Expected a list of items but got type "{input_type}".'),
         'empty': _('This list may not be empty.')

rest_framework/renderers.py

@@ -8,6 +8,7 @@ REST framework also provides an HTML renderer that renders the browsable API.
 """
 import base64
 from collections import OrderedDict
+from typing import Optional
 from urllib import parse
 
 from django import forms
@@ -42,9 +43,9 @@ class BaseRenderer:
     All renderers should extend this class, setting the `media_type`
     and `format` attributes, and override the `.render()` method.
     """
-    media_type = None
-    format = None
-    charset = 'utf-8'
+    media_type = None  # type: Optional[str]
+    format = None  # type: Optional[str]
+    charset = 'utf-8'  # type: Optional[str]
     render_style = 'text'
 
     def render(self, data, accepted_media_type=None, renderer_context=None):

rest_framework/serializers.py

@@ -15,6 +15,7 @@ import inspect
 import traceback
 from collections import OrderedDict
 from collections.abc import Mapping
+from typing import Type
 
 from django.core.exceptions import FieldDoesNotExist, ImproperlyConfigured
 from django.core.exceptions import ValidationError as DjangoValidationError
@@ -891,7 +892,7 @@ class ModelSerializer(Serializer):
     }
     if ModelDurationField is not None:
         serializer_field_mapping[ModelDurationField] = DurationField
-    serializer_related_field = PrimaryKeyRelatedField
+    serializer_related_field = PrimaryKeyRelatedField  # type: Type[RelatedField]
     serializer_related_to_field = SlugRelatedField
     serializer_url_field = HyperlinkedIdentityField
     serializer_choice_field = ChoiceField

rest_framework/test.py

@@ -115,7 +115,7 @@ if requests is not None:
             return super().request(method, url, *args, **kwargs)
 
 else:
-    def RequestsClient(*args, **kwargs):
+    def RequestsClient(*args, **kwargs):  # type: ignore
         raise ImproperlyConfigured('requests must be installed in order to use RequestsClient.')
 
 
@@ -131,7 +131,7 @@ if coreapi is not None:
             return self._session
 
 else:
-    def CoreAPIClient(*args, **kwargs):
+    def CoreAPIClient(*args, **kwargs):  # type: ignore
         raise ImproperlyConfigured('coreapi must be installed in order to use CoreAPIClient.')
 
 

rest_framework/throttling.py

@@ -2,6 +2,7 @@
 Provides various throttling policies.
 """
 import time
+from typing import Optional
 
 from django.core.cache import cache as default_cache
 from django.core.exceptions import ImproperlyConfigured
@@ -62,7 +63,7 @@ class SimpleRateThrottle(BaseThrottle):
     cache = default_cache
     timer = time.time
     cache_format = 'throttle_%(scope)s_%(ident)s'
-    scope = None
+    scope = None  # type: Optional[str]
     THROTTLE_RATES = api_settings.DEFAULT_THROTTLE_RATES
 
     def __init__(self):

rest_framework/views.py

@@ -1,6 +1,8 @@
 """
 Provides an APIView class that is the base of all views in REST framework.
 """
+from typing import Optional
+
 from django.conf import settings
 from django.core.exceptions import PermissionDenied
 from django.db import connection, models, transaction
@@ -15,6 +17,7 @@ from rest_framework import exceptions, status
 from rest_framework.request import Request
 from rest_framework.response import Response
 from rest_framework.schemas import DefaultSchema
+from rest_framework.schemas.inspectors import ViewInspector
 from rest_framework.settings import api_settings
 from rest_framework.utils import formatting
 
@@ -116,7 +119,7 @@ class APIView(View):
     # Allow dependency injection of other settings to make testing easier.
     settings = api_settings
 
-    schema = DefaultSchema()
+    schema = DefaultSchema()  # type: Optional[ViewInspector]
 
     @classmethod
     def as_view(cls, **initkwargs):

tox.ini

@@ -5,7 +5,7 @@ envlist =
        {py35,py36,py37}-django21
        {py35,py36,py37}-django22
        {py36,py37}-djangomaster,
-       base,dist,lint,docs,
+       base,dist,lint,docs,mypy,
 
 [travis:env]
 DJANGO =
@@ -57,3 +57,9 @@ commands = mkdocs build
 deps =
        -rrequirements/requirements-testing.txt
        -rrequirements/requirements-documentation.txt
+
+[testenv:mypy]
+basepython = python3.7
+commands = mypy ./rest_framework
+deps =
+        -rrequirements/requirements-mypy.txt