Move DateTimeData from WorkGraph to here

Author: superstar54

pyproject.toml

@@ -65,6 +65,7 @@ Source = "https://github.com/aiidateam/aiida-pythonjob"
 "pythonjob.numpy.int64" = "aiida.orm.nodes.data.int:Int"
 "pythonjob.numpy.bool_" = "aiida.orm.nodes.data.bool:Bool"
 "pythonjob.numpy.ndarray" = "aiida.orm.nodes.data.array.array.ArrayData"
+"pythonjob.datetime.datetime" = "pythonjob.orm.data:DateTimeData"
 
 [project.entry-points."aiida.calculations"]
 "pythonjob.pythonjob" = "aiida_pythonjob.calculations.pythonjob:PythonJob"

src/aiida_pythonjob/data/common_data.py

@@ -1,4 +1,7 @@
+import datetime
+
 from aiida import orm
+from aiida.orm import Data
 
 
 class NoneData(orm.Data):
@@ -24,3 +27,22 @@ def __repr__(self) -> str:
 
     def __str__(self) -> str:
         return "NoneData()"
+
+
+class DateTimeData(Data):
+    """AiiDA node to store a datetime.datetime object."""
+
+    def __init__(self, value: datetime.datetime, **kwargs):
+        if not isinstance(value, datetime.datetime):
+            raise TypeError(f"Expected datetime.datetime, got {type(value)}")
+        super().__init__(**kwargs)
+        # Store as ISO string for portability
+        self.base.attributes.set("datetime", value.isoformat())
+
+    @property
+    def value(self) -> datetime.datetime:
+        """Return the stored datetime as a datetime object."""
+        return datetime.datetime.fromisoformat(self.base.attributes.get("datetime"))
+
+    def __str__(self):
+        return str(self.value)