Fix recursive deserialization of cbor bytes

Author: nielstron

pycardano/serialization.py

@@ -2,6 +2,8 @@
 
 from __future__ import annotations
 
+import typing
+
 import re
 from collections import OrderedDict, UserList, defaultdict
 from copy import deepcopy
@@ -413,65 +415,67 @@ def _restore_dataclass_field(
     Returns:
         Union[:const:`Primitive`, CBORSerializable]: A CBOR primitive or a CBORSerializable.
     """
+
     if "object_hook" in f.metadata:
         return f.metadata["object_hook"](v)
-    elif isclass(f.type) and issubclass(f.type, CBORSerializable):
-        return f.type.from_primitive(v)
-    elif hasattr(f.type, "__origin__") and (f.type.__origin__ is list):
-        t_args = f.type.__args__
+    return _restore_typed_primitive(f.type, v)
+
+
+def _restore_typed_primitive(
+    t: typing.Type, v: Primitive
+) -> Union[Primitive, CBORSerializable]:
+    """Try to restore a value back to its original type based on information given in field.
+
+    Args:
+        f (type): A type
+        v (:const:`Primitive`): A CBOR primitive.
+
+    Returns:
+        Union[:const:`Primitive`, CBORSerializable]: A CBOR primitive or a CBORSerializable.
+    """
+    if t in PRIMITIVE_TYPES and isinstance(v, t):
+        return v
+    elif isclass(t) and issubclass(t, CBORSerializable):
+        return t.from_primitive(v)
+    elif hasattr(t, "__origin__") and (t.__origin__ is list):
+        t_args = t.__args__
         if len(t_args) != 1:
             raise DeserializeException(
                 f"List types need exactly one type argument, but got {t_args}"
             )
         t = t_args[0]
         if not isinstance(v, list):
             raise DeserializeException(f"Expected type list but got {type(v)}")
-        if isclass(t) and issubclass(t, CBORSerializable):
-            return IndefiniteList([t.from_primitive(w) for w in v])
-        else:
-            return IndefiniteList(v)
-    elif isclass(f.type) and issubclass(f.type, IndefiniteList):
+        return IndefiniteList([_restore_typed_primitive(t, w) for w in v])
+    elif isclass(t) and issubclass(t, IndefiniteList):
         return IndefiniteList(v)
-    elif hasattr(f.type, "__origin__") and (f.type.__origin__ is dict):
-        t_args = f.type.__args__
+    elif hasattr(t, "__origin__") and (t.__origin__ is dict):
+        t_args = t.__args__
         if len(t_args) != 2:
             raise DeserializeException(
                 f"Dict types need exactly two type arguments, but got {t_args}"
             )
         key_t = t_args[0]
         val_t = t_args[1]
-        if isclass(key_t) and issubclass(key_t, CBORSerializable):
-            key_converter = key_t.from_primitive
-        else:
-            key_converter = _identity
-        if isclass(val_t) and issubclass(val_t, CBORSerializable):
-            val_converter = val_t.from_primitive
-        else:
-            val_converter = _identity
         if not isinstance(v, dict):
             raise DeserializeException(f"Expected dict type but got {type(v)}")
-        return {key_converter(key): val_converter(val) for key, val in v.items()}
-    elif hasattr(f.type, "__origin__") and (
-        f.type.__origin__ is Union or f.type.__origin__ is Optional
+        return {
+            _restore_typed_primitive(key_t, key): _restore_typed_primitive(val_t, val)
+            for key, val in v.items()
+        }
+    elif hasattr(t, "__origin__") and (
+        t.__origin__ is Union or t.__origin__ is Optional
     ):
-        t_args = f.type.__args__
+        t_args = t.__args__
         for t in t_args:
-            if isclass(t) and issubclass(t, IndefiniteList):
-                return IndefiniteList(v)
-            elif isclass(t) and issubclass(t, CBORSerializable):
-                try:
-                    return t.from_primitive(v)
-                except DeserializeException:
-                    pass
-            else:
-                if not isclass(t) and hasattr(t, "__origin__"):
-                    t = t.__origin__
-                if t in PRIMITIVE_TYPES and isinstance(v, t):
-                    return v
+            try:
+                return _restore_typed_primitive(t, v)
+            except DeserializeException:
+                pass
         raise DeserializeException(
             f"Cannot deserialize object: \n{v}\n in any valid type from {t_args}."
         )
-    return v
+    raise DeserializeException(f"Cannot deserialize object: \n{v}\n to type {t}.")
 
 
 ArrayBase = TypeVar("ArrayBase", bound="ArrayCBORSerializable")
@@ -556,8 +560,8 @@ def to_shallow_primitive(self) -> List[Primitive]:
         return primitives
 
     @classmethod
-    @limit_primitive_type(list)
-    def from_primitive(cls: Type[ArrayBase], values: list) -> ArrayBase:
+    @limit_primitive_type(list, tuple)
+    def from_primitive(cls: Type[ArrayBase], values: Union[list, tuple]) -> ArrayBase:
         """Restore a primitive value to its original class type.
 
         Args:

test/pycardano/test_serialization.py

@@ -1,3 +1,5 @@
+from typing import Union
+
 from dataclasses import dataclass, field
 from test.pycardano.util import check_two_way_cbor
 
@@ -40,7 +42,7 @@ def test_array_cbor_serializable():
     @dataclass
     class Test1(ArrayCBORSerializable):
         a: str
-        b: str = None
+        b: Union[str, None] = None
 
     @dataclass
     class Test2(ArrayCBORSerializable):
@@ -87,7 +89,7 @@ class Test1(MapCBORSerializable):
 
     @dataclass
     class Test2(MapCBORSerializable):
-        c: str = None
+        c: Union[str, None] = None
         test1: Test1 = field(default_factory=Test1)
 
     t = Test2(test1=Test1(a="a"))