Add support for SerializerMethodField (#179)

Closes #137, #179.

testproj/users/method_serializers_with_typing.py

@@ -0,0 +1,69 @@
+import datetime
+import decimal
+import uuid
+
+from rest_framework import serializers
+
+
+class Unknown(object):
+    pass
+
+
+class MethodFieldExampleSerializer(serializers.Serializer):
+    """
+    Implementation of SerializerMethodField using type hinting for Python >= 3.5
+    """
+
+    hinted_bool = serializers.SerializerMethodField(
+        help_text="the type hint on the method should determine this to be a bool")
+
+    def get_hinted_bool(self, obj) -> bool:
+        return True
+
+    hinted_int = serializers.SerializerMethodField(
+        help_text="the type hint on the method should determine this to be an integer")
+
+    def get_hinted_int(self, obj) -> int:
+        return 1
+
+    hinted_float = serializers.SerializerMethodField(
+        help_text="the type hint on the method should determine this to be a number")
+
+    def get_hinted_float(self, obj) -> float:
+        return 1.0
+
+    hinted_decimal = serializers.SerializerMethodField(
+        help_text="the type hint on the method should determine this to be a decimal")
+
+    def get_hinted_decimal(self, obj) -> decimal.Decimal:
+        return decimal.Decimal(1)
+
+    hinted_datetime = serializers.SerializerMethodField(
+        help_text="the type hint on the method should determine this to be a datetime")
+
+    def get_hinted_datetime(self, obj) -> datetime.datetime:
+        return datetime.datetime.now()
+
+    hinted_date = serializers.SerializerMethodField(
+        help_text="the type hint on the method should determine this to be a date")
+
+    def get_hinted_date(self, obj) -> datetime.date:
+        return datetime.date.today()
+
+    hinted_uuid = serializers.SerializerMethodField(
+        help_text="the type hint on the method should determine this to be a uuid")
+
+    def get_hinted_uuid(self, obj) -> uuid.UUID:
+        return uuid.uuid4()
+
+    hinted_unknown = serializers.SerializerMethodField(
+        help_text="type hint is unknown, so is expected to fallback to string")
+
+    def get_hinted_unknown(self, obj) -> Unknown:
+        return Unknown()
+
+    non_hinted_number = serializers.SerializerMethodField(
+        help_text="No hint on the method, so this is expected to fallback to string")
+
+    def get_non_hinted_number(self, obj):
+        return 1.0

testproj/users/method_serializers_without_typing.py

@@ -0,0 +1,82 @@
+import datetime
+import decimal
+import uuid
+
+from rest_framework import serializers
+
+from drf_yasg.utils import swagger_serializer_method
+
+
+class Unknown(object):
+    pass
+
+
+class MethodFieldExampleSerializer(serializers.Serializer):
+    """
+    Fallback implementation of SerializerMethodField type hinting for Python < 3.5
+
+    `->` syntax isn't supported, instead decorate with a serializer that returns the same type
+    a bit of a hack, but it provides a cross-check between hinting and decorator functionality.
+    """
+
+    hinted_bool = serializers.SerializerMethodField(
+        help_text="the type hint on the method should determine this to be a bool")
+
+    @swagger_serializer_method(serializer=serializers.BooleanField)
+    def get_hinted_bool(self, obj):
+        return True
+
+    hinted_int = serializers.SerializerMethodField(
+        help_text="the type hint on the method should determine this to be an integer")
+
+    @swagger_serializer_method(serializer=serializers.IntegerField)
+    def get_hinted_int(self, obj):
+        return 1
+
+    hinted_float = serializers.SerializerMethodField(
+        help_text="the type hint on the method should determine this to be a number")
+
+    @swagger_serializer_method(serializer=serializers.FloatField)
+    def get_hinted_float(self, obj):
+        return 1.0
+
+    hinted_decimal = serializers.SerializerMethodField(
+        help_text="the type hint on the method should determine this to be a decimal")
+
+    # note that in this case an instance is required since DecimalField has required arguments
+    @swagger_serializer_method(serializer=serializers.DecimalField(max_digits=6, decimal_places=4))
+    def get_hinted_decimal(self, obj):
+        return decimal.Decimal(1)
+
+    hinted_datetime = serializers.SerializerMethodField(
+        help_text="the type hint on the method should determine this to be a datetime")
+
+    @swagger_serializer_method(serializer=serializers.DateTimeField)
+    def get_hinted_datetime(self, obj):
+        return datetime.datetime.now()
+
+    hinted_date = serializers.SerializerMethodField(
+        help_text="the type hint on the method should determine this to be a date")
+
+    @swagger_serializer_method(serializer=serializers.DateField)
+    def get_hinted_date(self, obj):
+        return datetime.date.today()
+
+    hinted_uuid = serializers.SerializerMethodField(
+        help_text="the type hint on the method should determine this to be a uuid")
+
+    @swagger_serializer_method(serializer=serializers.UUIDField)
+    def get_hinted_uuid(self, obj):
+        return uuid.uuid4()
+
+    hinted_unknown = serializers.SerializerMethodField(
+        help_text="type hint is unknown, so is expected to fallback to string")
+
+    def get_hinted_unknown(self, obj):
+        return Unknown()
+
+    non_hinted_number = serializers.SerializerMethodField(
+        help_text="No hint on the method, so this is expected to fallback to string")
+
+    def get_non_hinted_number(self, obj):
+        return 1.0

testproj/users/serializers.py

@@ -1,8 +1,19 @@
 from django.contrib.auth.models import User
 from rest_framework import serializers
 
+from drf_yasg.utils import swagger_serializer_method
 from snippets.models import Snippet
 
+try:
+    import typing
+    from .method_serializers_with_typing import MethodFieldExampleSerializer
+except ImportError:
+    from .method_serializers_without_typing import MethodFieldExampleSerializer
+
+
+class OtherStuffSerializer(serializers.Serializer):
+    foo = serializers.CharField()
+
 
 class UserSerializerrr(serializers.ModelSerializer):
     snippets = serializers.PrimaryKeyRelatedField(many=True, queryset=Snippet.objects.all())
@@ -10,10 +21,61 @@ class UserSerializerrr(serializers.ModelSerializer):
     last_connected_ip = serializers.IPAddressField(help_text="i'm out of ideas", protocol='ipv4', read_only=True)
     last_connected_at = serializers.DateField(help_text="really?", read_only=True)
 
+    other_stuff = serializers.SerializerMethodField(
+        help_text="the decorator should determine the serializer class for this")
+
+    hint_example = MethodFieldExampleSerializer()
+
+    @swagger_serializer_method(serializer=OtherStuffSerializer)
+    def get_other_stuff(self, obj):
+        """
+        method_field that uses a serializer internally.
+
+        By using the decorator, we can tell drf-yasg how to represent this in Swagger
+        :param obj:
+        :return:
+        """
+        return OtherStuffSerializer().data
+
+    help_text_example_1 = serializers.SerializerMethodField(
+        help_text="help text on field is set, so this should appear in swagger"
+    )
+
+    @swagger_serializer_method(serializer=serializers.IntegerField(
+        help_text="decorated instance help_text shouldn't appear in swagger because field has priority"))
+    def get_help_text_example_1(self):
+        """
+        method docstring shouldn't appear in swagger because field has priority
+        :return:
+        """
+        return 1
+
+    help_text_example_2 = serializers.SerializerMethodField()
+
+    @swagger_serializer_method(serializer=serializers.IntegerField(
+        help_text="instance help_text is set, so should appear in swagger"))
+    def get_help_text_example_2(self):
+        """
+        method docstring shouldn't appear in swagger because decorator has priority
+        :return:
+        """
+        return 1
+
+    help_text_example_3 = serializers.SerializerMethodField()
+
+    @swagger_serializer_method(serializer=serializers.IntegerField())
+    def get_help_text_example_3(self):
+        """
+        docstring is set so should appear in swagger as fallback
+        :return:
+        """
+        return 1
+
     class Meta:
         model = User
         fields = ('id', 'username', 'email', 'articles', 'snippets',
-                  'last_connected_ip', 'last_connected_at', 'article_slugs')
+                  'last_connected_ip', 'last_connected_at', 'article_slugs', 'other_stuff', 'hint_example',
+                  'help_text_example_1', 'help_text_example_2', 'help_text_example_3')
 
 
 class UserListQuerySerializer(serializers.Serializer):