Fix deprecated UnicodeDelimitedTuple due to deprecated `_field_type…

…s` (#35)

_field_types was removed in Python 3.9 causing UnicodeDelimitedTupleAttribute to not function properly.

.github/workflows/test.yaml

@@ -12,6 +12,7 @@ jobs:
       matrix:
         python-version:
           - "3.8"
+          - "3.9"
 
     services:
       dynamodb-local:

pynamodb_attributes/timedelta.py

@@ -7,7 +7,7 @@
 
 
 class TimedeltaAttribute(Attribute[timedelta]):
-    """ "
+    """
     Stores a timedelta as a number of seconds (truncated).
 
     >>> class MyModel(Model):
@@ -33,15 +33,15 @@ def __set__(self, instance: Any, value: Optional[Any]) -> None:
 
 
 class TimedeltaMsAttribute(TimedeltaAttribute):
-    """ "
+    """
     Stores a timedelta as a number of milliseconds AKA ms (truncated).
     """
 
     _multiplier = 1000.0
 
 
 class TimedeltaUsAttribute(TimedeltaAttribute):
-    """ "
+    """
     Stores a timedelta as a number of microseconds AKA μs (truncated).
     """
 

pynamodb_attributes/timestamp.py

@@ -8,7 +8,7 @@
 
 
 class TimestampAttribute(Attribute[datetime]):
-    """ "
+    """
     Stores time as a Unix epoch timestamp (in seconds) in a DynamoDB number.
 
     >>> class MyModel(Model):
@@ -37,15 +37,15 @@ def __set__(self, instance: Any, value: Optional[Any]) -> None:
 
 
 class TimestampMsAttribute(TimestampAttribute):
-    """ "
+    """
     Stores time as a Unix epoch timestamp in milliseconds (ms) in a DynamoDB number.
     """
 
     _multiplier = 1000.0
 
 
 class TimestampUsAttribute(TimestampAttribute):
-    """ "
+    """
     Stores times as a Unix epoch timestamp in microseconds (μs) in a DynamoDB number.
     """
 

pynamodb_attributes/unicode_delimited_tuple.py

@@ -1,4 +1,5 @@
 from typing import Any
+from typing import get_type_hints
 from typing import List
 from typing import Tuple
 from typing import Type
@@ -44,12 +45,18 @@ def __init__(
         self.delimiter = delimiter
 
     def deserialize(self, value: str) -> T:
-        fields = getattr(self.tuple_type, "_fields", None)
-        field_types = getattr(self.tuple_type, "_field_types", None)
-        if fields and field_types:
-            values = value.split(self.delimiter, maxsplit=len(fields))
+        field_types = get_type_hints(self.tuple_type)
+
+        if field_types:
+            values = value.split(self.delimiter, maxsplit=len(field_types))
             return self.tuple_type(
-                **{f: field_types[f](v) for f, v in zip(fields, values)}
+                **{
+                    field_name: field_type(value)
+                    for (field_name, field_type), value in zip(
+                        field_types.items(),
+                        values,
+                    )
+                }
             )
         else:
             return self.tuple_type(value.split(self.delimiter))