feat(numpy): Support serialization of numpy.datetime64

Author: kmsquire

Makefile

@@ -25,7 +25,7 @@ examples:
 	pushd examples && $(POETRY) run $(PYTHON) runner.py && popd
 
 coverage:
-	$(POETRY) run pytest tests --doctest-modules serde -v -nauto --cov=serde --cov-report term --cov-report xml
+	$(POETRY) run pytest tests --doctest-modules serde -v -nauto --cov=serde --cov-report term --cov-report xml --cov-report html
 
 pep8:
 	$(POETRY) run flake8

serde/de.py

@@ -519,7 +519,13 @@ def render(self, arg: DeField) -> str:
             res = self.tuple(arg)
         elif is_enum(arg.type):
             res = self.enum(arg)
-        elif is_primitive(arg.type) and not is_numpy_scalar(arg.type):
+        elif is_numpy_scalar(arg.type):
+            self.import_numpy = True
+            res = deserialize_numpy_scalar(arg)
+        elif is_numpy_array(arg.type):
+            self.import_numpy = True
+            res = deserialize_numpy_array(arg)
+        elif is_primitive(arg.type):
             res = self.primitive(arg)
         elif is_union(arg.type):
             res = self.union_func(arg)
@@ -539,12 +545,6 @@ def render(self, arg: DeField) -> str:
         elif is_generic(arg.type):
             arg.type = get_origin(arg.type)
             res = self.render(arg)
-        elif is_numpy_scalar(arg.type):
-            self.import_numpy = True
-            res = deserialize_numpy_scalar(arg)
-        elif is_numpy_array(arg.type):
-            self.import_numpy = True
-            res = deserialize_numpy_array(arg)
         else:
             return f"raise_unsupported_type({arg.data})"
 

serde/numpy.py

@@ -19,6 +19,8 @@ def fullname(klass):
     def encode_numpy(obj: Any):
         if isinstance(obj, np.ndarray):
             return obj.tolist()
+        if isinstance(obj, np.datetime64):
+            return obj.item().isoformat()
         if isinstance(obj, np.generic):
             return obj.item()
         raise TypeError(f"Object of type {fullname(type(obj))} is not serializable")
@@ -44,6 +46,12 @@ def is_numpy_scalar(typ) -> bool:
         except TypeError:
             return False
 
+    def is_numpy_datetime(typ) -> bool:
+        try:
+            return issubclass(typ, np.datetime64)
+        except TypeError:
+            return False
+
     def serialize_numpy_scalar(arg) -> str:
         return f"{arg.varname}.item()"
 
@@ -59,6 +67,9 @@ def is_numpy_array(typ) -> bool:
     def serialize_numpy_array(arg) -> str:
         return f"{arg.varname}.tolist()"
 
+    def serialize_numpy_datetime(arg) -> str:
+        return f"{arg.varname}.item().isoformat()"
+
     def deserialize_numpy_array(arg) -> str:
         if is_bare_numpy_array(arg.type):
             return f"numpy.array({arg.data})"
@@ -79,6 +90,9 @@ def deserialize_numpy_array_direct(typ, arg):
     def is_numpy_scalar(typ) -> bool:
         return False
 
+    def is_numpy_datetime(typ) -> bool:
+        return False
+
     def serialize_numpy_scalar(arg) -> str:
         return ""
 
@@ -91,6 +105,9 @@ def is_numpy_array(typ) -> bool:
     def serialize_numpy_array(arg) -> str:
         return ""
 
+    def serialize_numpy_datetime(arg) -> str:
+        return ""
+
     def deserialize_numpy_array(arg) -> str:
         return ""
 

serde/se.py

@@ -55,7 +55,14 @@
     raise_unsupported_type,
     union_func_name,
 )
-from .numpy import is_numpy_array, is_numpy_scalar, serialize_numpy_array, serialize_numpy_scalar
+from .numpy import (
+    is_numpy_array,
+    is_numpy_datetime,
+    is_numpy_scalar,
+    serialize_numpy_array,
+    serialize_numpy_datetime,
+    serialize_numpy_scalar,
+)
 
 __all__ = ["serialize", "is_serializable", "to_dict", "to_tuple"]
 
@@ -589,7 +596,13 @@ def render(self, arg: SeField) -> str:
             res = self.tuple(arg)
         elif is_enum(arg.type):
             res = self.enum(arg)
-        elif is_primitive(arg.type) and not is_numpy_scalar(arg.type):
+        elif is_numpy_datetime(arg.type):
+            res = serialize_numpy_datetime(arg)
+        elif is_numpy_scalar(arg.type):
+            res = serialize_numpy_scalar(arg)
+        elif is_numpy_array(arg.type):
+            res = serialize_numpy_array(arg)
+        elif is_primitive(arg.type):
             res = self.primitive(arg)
         elif is_union(arg.type):
             res = self.union_func(arg)
@@ -604,10 +617,6 @@ def render(self, arg: SeField) -> str:
         elif is_generic(arg.type):
             arg.type = get_origin(arg.type)
             res = self.render(arg)
-        elif is_numpy_scalar(arg.type):
-            res = serialize_numpy_scalar(arg)
-        elif is_numpy_array(arg.type):
-            res = serialize_numpy_array(arg)
         else:
             res = f"raise_unsupported_type({arg.varname})"
 

tests/test_numpy.py

@@ -82,6 +82,14 @@ def __eq__(self, other):
         assert type(de_value) == typ
         assert type(de_value).dtype == field.type.dtype
 
+    @serde.serde(**opt)
+    class NumpyDate:
+        d: np.datetime64
+
+    date_test = NumpyDate(np.datetime64(10, "Y"))
+
+    assert de(NumpyDate, se(date_test)) == date_test
+
 
 @pytest.mark.parametrize("opt", opt_case, ids=opt_case_ids())
 @pytest.mark.parametrize("se,de", format_json + format_msgpack)
@@ -138,7 +146,10 @@ class MisTyped:
         np.array([np.bool_(i) for i in [True, False]]),
     )
 
-    assert de(MisTyped, se(test2)) == expected
+    assert de(MisTyped, se(test3)) == expected
+
+    np_datetime = np.datetime64("2022-04-27")
+    assert de(np.datetime64, se(np_datetime)) == np_datetime
 
     for value in [np.int32(1), np.int64(1), np.bool_(False), np.bool_(True), int(1), False, True]:
         typ = type(value)