Support optional type in dataclass

Signed-off-by: Kevin Su <[email protected]>

flytekit/core/type_engine.py

@@ -449,6 +449,8 @@ def _deserialize_flyte_type(self, python_val: T, expected_python_type: Type) ->
             return python_val
 
     def _fix_val_int(self, t: typing.Type, val: typing.Any) -> typing.Any:
+        if val is None:
+            return val
         if t == int:
             return int(val)
 

tests/flytekit/unit/core/test_type_engine.py

@@ -155,13 +155,14 @@ class Bar(object):
     @dataclass_json
     @dataclass()
     class Foo(object):
+        u: typing.Optional[int]
         v: typing.Optional[int]
         w: int
         x: typing.List[int]
         y: typing.Dict[str, str]
         z: Bar
 
-    foo = Foo(v=5, w=1, x=[1], y={"hello": "10"}, z=Bar(w=None, x=1.0, y="hello", z={"world": False}))
+    foo = Foo(u=5, v=None, w=1, x=[1], y={"hello": "10"}, z=Bar(w=None, x=1.0, y="hello", z={"world": False}))
     generic = _json_format.Parse(typing.cast(DataClassJsonMixin, foo).to_json(), _struct.Struct())
     lv = Literal(collection=LiteralCollection(literals=[Literal(scalar=Scalar(generic=generic))]))
 
@@ -173,12 +174,14 @@ class Foo(object):
 
     pv = transformer.to_python_value(ctx, lv, expected_python_type=typing.List[foo_class])
     assert isinstance(pv, list)
+    assert pv[0].u == foo.u
     assert pv[0].v == foo.v
     assert pv[0].w == foo.w
     assert pv[0].x == foo.x
     assert pv[0].y == foo.y
     assert pv[0].z.x == foo.z.x
-    assert type(pv[0].v) == int
+    assert type(pv[0].u) == int
+    assert pv[0].v is None
     assert type(pv[0].w) == int
     assert type(pv[0].z.x) == float
     assert pv[0].z.y == foo.z.y
@@ -1178,6 +1181,7 @@ def test_pass_annotated_to_downstream_tasks():
     """
     Test to confirm that the loaded dataframe is not affected and can be used in @dynamic.
     """
+
     # pandas dataframe hash function
     def hash_pandas_dataframe(df: pd.DataFrame) -> str:
         return str(pd.util.hash_pandas_object(df))