fix: support generic dataclass

dataclasses_json/core.py

@@ -24,7 +24,8 @@
  _get_type_arg_param,
  _get_type_args, _is_counter,
  _NO_ARGS,
- _issubclass_safe, _is_tuple)
+ _issubclass_safe, _is_tuple,
+ _is_generic_dataclass)
 
 Json = Union[dict, list, str, int, float, bool, None]
 
@@ -259,8 +260,9 @@ def _is_supported_generic(type_):
  return False
  not_str = not _issubclass_safe(type_, str)
  is_enum = _issubclass_safe(type_, Enum)
+ is_generic_dataclass = _is_generic_dataclass(type_)
  return (not_str and _is_collection(type_)) or _is_optional(
- type_) or is_union_type(type_) or is_enum
+ type_) or is_union_type(type_) or is_enum or is_generic_dataclass
 
 
 def _decode_generic(type_, value, infer_missing):
@@ -298,6 +300,9 @@ def _decode_generic(type_, value, infer_missing):
  except (TypeError, AttributeError):
  pass
  res = materialize_type(xs)
+ elif _is_generic_dataclass(type_):
+ origin = _get_type_origin(type_)
+ res = _decode_dataclass(origin, value, infer_missing)
  else: # Optional or Union
  _args = _get_type_args(type_)
  if _args is _NO_ARGS:

dataclasses_json/utils.py

@@ -2,6 +2,7 @@
 import sys
 from datetime import datetime, timezone
 from collections import Counter
+from dataclasses import is_dataclass # type: ignore
 from typing import (Collection, Mapping, Optional, TypeVar, Any, Type, Tuple,
  Union, cast)
 
@@ -164,6 +165,10 @@ def _is_nonstr_collection(type_):
  and not _issubclass_safe(type_, str))
 
 
+def _is_generic_dataclass(type_):
+ return is_dataclass(_get_type_origin(type_))
+
+
 def _timestamp_to_dt_aware(timestamp: float):
  tz = datetime.now(timezone.utc).astimezone().tzinfo
  dt = datetime.fromtimestamp(timestamp, tz=tz)

tests/test_generic_dataclass.py

@@ -0,0 +1,23 @@
+from dataclasses import dataclass
+from typing import Generic, TypeVar
+
+from dataclasses_json import dataclass_json
+
+T = TypeVar("T")
+
+
+@dataclass_json
+@dataclass
+class NestedClass(Generic[T]):
+ value: T
+
+
+@dataclass_json
+@dataclass
+class MyClass(Generic[T]):
+ nested: NestedClass[T]
+
+
+def test_dataclass_with_generic_dataclass_field():
+ a = MyClass(nested=NestedClass(value="value"))
+ assert MyClass.from_json(a.to_json()) == a