add IntegerSetAttribute

README.md

@@ -2,6 +2,7 @@ This Python 3 library contains compound and high-level PynamoDB attributes:
 
 - `FloatAttribute` – same as `NumberAttribute` but whose value is typed as `float`
 - `IntegerAttribute` – same as `NumberAttribute` but whose value is typed as `int` (rather than `float`)
+- `IntegerSetAttribute` – same as `NumberSetAttribute` but whose value is typed as `int` (rather than `float`)
 - `UnicodeDelimitedTupleAttribute` - a delimiter-separated value, useful for storing composite keys
 - `UnicodeEnumAttribute` - serializes a string-valued `Enum` into a Unicode (`S`-typed) attribute
 - `UnicodeProtobufEnumAttribute` - serializes a Protobuf enum into a Unicode (`S`-typed) attribute

pynamodb_attributes/__init__.py

@@ -1,5 +1,6 @@
 from .float import FloatAttribute
 from .integer import IntegerAttribute
+from .integer_set import IntegerSetAttribute
 from .integer_date import IntegerDateAttribute
 from .integer_enum import IntegerEnumAttribute
 from .timedelta import TimedeltaAttribute
@@ -16,6 +17,7 @@
 __all__ = [
     "FloatAttribute",
     "IntegerAttribute",
+    "IntegerSetAttribute",
     "IntegerDateAttribute",
     "IntegerEnumAttribute",
     "UnicodeDelimitedTupleAttribute",

pynamodb_attributes/integer_set.py

@@ -0,0 +1,15 @@
+from typing import Set
+
+from pynamodb.attributes import Attribute
+from pynamodb.attributes import NumberSetAttribute
+
+
+class IntegerSetAttribute(Attribute[Set[int]]):
+    """
+    Unlike NumberSetAttribute, this attribute has its type hinted as 'Set[int]'.
+    """
+
+    attr_type = NumberSetAttribute.attr_type
+    null = NumberSetAttribute.null
+    serialize = NumberSetAttribute.serialize  # type: ignore
+    deserialize = NumberSetAttribute.deserialize  # type: ignore

tests/integer_set_attribute_test.py

@@ -0,0 +1,56 @@
+from typing import Set
+
+import pytest
+from pynamodb.attributes import UnicodeAttribute
+from pynamodb.models import Model
+from typing_extensions import assert_type
+
+from pynamodb_attributes import IntegerSetAttribute
+from tests.connection import _connection
+from tests.meta import dynamodb_table_meta
+
+
+class MyModel(Model):
+    Meta = dynamodb_table_meta(__name__)
+
+    key = UnicodeAttribute(hash_key=True)
+    value = IntegerSetAttribute(null=True)
+
+
+assert_type(MyModel.value, IntegerSetAttribute)
+assert_type(MyModel().value, Set[int])
+
+
+@pytest.fixture(scope="module", autouse=True)
+def create_table():
+    MyModel.create_table()
+
+
+def test_serialization_non_null(uuid_key):
+    model = MyModel()
+    model.key = uuid_key
+    model.value = {456, 789}
+    model.save()
+
+    # verify underlying storage
+    item = _connection(MyModel).get_item(uuid_key)
+    assert item["Item"]["value"] == {"NS": ["456", "789"]}
+
+    # verify deserialization
+    model = MyModel.get(uuid_key)
+    assert model.value == {456, 789}
+
+
+def test_serialization_null(uuid_key):
+    model = MyModel()
+    model.key = uuid_key
+    model.value = None
+    model.save()
+
+    # verify underlying storage
+    item = _connection(MyModel).get_item(uuid_key)
+    assert "value" not in item["Item"]
+
+    # verify deserialization
+    model = MyModel.get(uuid_key)
+    assert model.value is None