Add output field to serializer method field

rest_framework/fields.py

@@ -1868,8 +1868,9 @@ class SerializerMethodField(Field):
         def get_extra_info(self, obj):
             return ...  # Calculate some data to return.
     """
-    def __init__(self, method_name=None, **kwargs):
+    def __init__(self, method_name=None, output_field=None, **kwargs):
         self.method_name = method_name
+        self.output_field = output_field
         kwargs['source'] = '*'
         kwargs['read_only'] = True
         super().__init__(**kwargs)

rest_framework/schemas/openapi.py

@@ -377,6 +377,9 @@ class AutoSchema(ViewInspector):
             data['type'] = 'object'
             return data
 
+        if isinstance(field, serializers.SerializerMethodField) and field.output_field:
+            return self.map_field(field.output_field)
+
         # Related fields.
         if isinstance(field, serializers.ManyRelatedField):
             return {

tests/schemas/test_openapi.py

@@ -132,6 +132,20 @@ class TestFieldMapping(TestCase):
         assert data['properties']['ro_field']['nullable'], "ro_field nullable must be true"
         assert data['properties']['ro_field']['readOnly'], "ro_field read_only must be true"
 
+    def test_serializer_method_field(self):
+        class MethodSerializer(serializers.Serializer):
+
+            method_field = serializers.SerializerMethodField(output_field=serializers.BooleanField())
+
+            def get_method_field(self, obj):
+                return True
+
+        inspector = AutoSchema()
+
+        inspector.map_serializer(MethodSerializer())
+        data = inspector.components['Method']
+        assert data['properties']['method_field']['type'] == 'boolean'
+
 
 @pytest.mark.skipif(uritemplate is None, reason='uritemplate not installed.')
 class TestOperationIntrospection(TestCase):