add SerializerMethodWithParamsField

rest_framework/fields.py

@@ -1909,3 +1909,25 @@ class ModelField(Field):
         if is_protected_type(value):
             return value
         return self.model_field.value_to_string(obj)
+
+
+class SerializerMethodWithParamsField(SerializerMethodField):
+    """
+    A read-only field allows you to pass optional parameters to a method in a SerializerMethodField.
+    For example:
+
+    class ExampleSerializer(Serializer):
+        extra_info = SerializerMethodWithParamsField(method_name='foo', bar='bar', ...)
+
+        def foo(self, obj, **kwargs):
+            bar = kwargs.get('bar', None)
+            return ...  # Calculate some data to return.
+    """
+
+    def __init__(self, method_name=None, **kwargs):
+        super().__init__(method_name, help_text=kwargs.pop('help_text', ''))
+        self._func_kwargs = kwargs
+
+    def to_representation(self, value):
+        method = getattr(self.parent, self.method_name)
+        return method(value, **self._func_kwargs)

rest_framework/serializers.py

@@ -55,7 +55,7 @@ from rest_framework.fields import (  # NOQA # isort:skip
     DictField, DurationField, EmailField, Field, FileField, FilePathField, FloatField,
     HiddenField, HStoreField, IPAddressField, ImageField, IntegerField, JSONField,
     ListField, ModelField, MultipleChoiceField, ReadOnlyField,
-    RegexField, SerializerMethodField, SlugField, TimeField, URLField, UUIDField,
+    RegexField, SerializerMethodField, SlugField, TimeField, URLField, UUIDField, SerializerMethodWithParamsField
 )
 from rest_framework.relations import (  # NOQA # isort:skip
     HyperlinkedIdentityField, HyperlinkedRelatedField, ManyRelatedField,

tests/test_fields.py

@@ -2713,3 +2713,22 @@ class TestValidationErrorCode:
                 ),
             ]
         }
+
+
+# Tests for SerializerMethodWithParamsField.
+# --------------------------------
+
+class TestSerializerMethodWithParamsField:
+    def test_serializer_method_field(self):
+        class ExampleSerializer(serializers.Serializer):
+            example_field_1 = serializers.SerializerMethodWithParamsField(method_name='foo', bar='bar_1')
+            example_field_2 = serializers.SerializerMethodWithParamsField(method_name='foo', bar='bar_2')
+
+            def foo(self, obj, **kwargs):
+                return 'ran foo(%d) with attr %s' % (obj['example_field'], kwargs.get('bar'))
+
+        serializer = ExampleSerializer({'example_field': 123})
+        assert serializer.data == {
+            'example_field_1': 'ran foo(123) with attr bar_1',
+            'example_field_2': 'ran foo(123) with attr bar_2',
+        }