From 9b241eb9ec25220dac527c230215f926b23779a2 Mon Sep 17 00:00:00 2001
From: superstar54 <xingwang1991@gmail.com>
Date: Mon, 26 Jan 2026 14:59:23 +0100
Subject: [PATCH 1/3] Add function data

---
 pyproject.toml                          |  1 +
 src/aiida_pythonjob/data/__init__.py    | 10 ++++--
 src/aiida_pythonjob/data/common_data.py | 48 +++++++++++++++++++++++++
 3 files changed, 57 insertions(+), 2 deletions(-)

diff --git a/pyproject.toml b/pyproject.toml
index b509860..063fe8a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -54,6 +54,7 @@ Source = "https://github.com/aiidateam/aiida-pythonjob"
 "pythonjob.jsonable_data" = "aiida_pythonjob.data.jsonable_data:JsonableData"
 "pythonjob.ase.atoms.Atoms" = "aiida_pythonjob.data.atoms:AtomsData"
 "pythonjob.builtins.NoneType" = "aiida_pythonjob.data.common_data:NoneData"
+"pythonjob.builtins.function" = "aiida_pythonjob.data.common_data:FunctionData"
 "pythonjob.datetime.datetime" = "aiida_pythonjob.data.common_data:DateTimeData"
 
 [project.entry-points."aiida.calculations"]
diff --git a/src/aiida_pythonjob/data/__init__.py b/src/aiida_pythonjob/data/__init__.py
index 1718f43..30a466e 100644
--- a/src/aiida_pythonjob/data/__init__.py
+++ b/src/aiida_pythonjob/data/__init__.py
@@ -1,5 +1,11 @@
-from .common_data import DateTimeData
+from .common_data import DateTimeData, FunctionData
 from .pickled_data import PickledData
 from .serializer import general_serializer, serialize_to_aiida_nodes
 
-__all__ = ("DateTimeData", "PickledData", "general_serializer", "serialize_to_aiida_nodes")
+__all__ = (
+    "DateTimeData",
+    "FunctionData",
+    "PickledData",
+    "general_serializer",
+    "serialize_to_aiida_nodes",
+)
diff --git a/src/aiida_pythonjob/data/common_data.py b/src/aiida_pythonjob/data/common_data.py
index aaf7c7a..055945f 100644
--- a/src/aiida_pythonjob/data/common_data.py
+++ b/src/aiida_pythonjob/data/common_data.py
@@ -46,3 +46,51 @@ def value(self) -> datetime.datetime:
 
     def __str__(self):
         return str(self.value)
+
+
+class FunctionData(Data):
+    """AiiDA node to store a Python function path."""
+
+    def __init__(self, value, **kwargs):
+        module = getattr(value, "__module__", None)
+        qualname = getattr(value, "__qualname__", None) or getattr(value, "__name__", None)
+        if not module or not qualname:
+            raise TypeError(f"Expected a function-like object, got {type(value)}")
+        super().__init__(**kwargs)
+        self.base.attributes.set("module_path", module)
+        self.base.attributes.set("qualname", qualname)
+
+    @property
+    def module_path(self) -> str:
+        return self.base.attributes.get("module_path")
+
+    @property
+    def qualname(self) -> str:
+        return self.base.attributes.get("qualname")
+
+    @property
+    def path(self) -> str:
+        return f"{self.module_path}:{self.qualname}"
+
+    @property
+    def value(self):
+        from importlib import import_module
+
+        try:
+            module = import_module(self.module_path)
+        except Exception as exc:
+            raise ImportError(
+                f"Failed to import function module '{self.module_path}' for FunctionData '{self.path}': {exc}"
+            ) from exc
+
+        obj = module
+        try:
+            for part in self.qualname.split("."):
+                obj = getattr(obj, part)
+        except AttributeError as exc:
+            raise ImportError(f"Failed to resolve function '{self.path}': attribute '{part}' not found.") from exc
+
+        return obj
+
+    def __str__(self) -> str:
+        return self.path

From d0754a3b639568ceeb82b92517fb3d52ac627426 Mon Sep 17 00:00:00 2001
From: superstar54 <xingwang1991@gmail.com>
Date: Mon, 26 Jan 2026 15:03:05 +0100
Subject: [PATCH 2/3] update test

---
 tests/test_data.py | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/tests/test_data.py b/tests/test_data.py
index c6d7f53..bd96173 100644
--- a/tests/test_data.py
+++ b/tests/test_data.py
@@ -115,6 +115,18 @@ def test_datetime_data():
         DateTimeData("2024-06-01")
 
 
+def _sample_function():
+    return "ok"
+
+
+def test_function_data():
+    from aiida_pythonjob.data.common_data import FunctionData
+
+    func_data = FunctionData(_sample_function)
+    assert func_data.path.endswith(":_sample_function")
+    assert func_data.value is _sample_function
+
+
 def test_jsonable_data_pydantic_and_dataclass():
     pytest.importorskip("pydantic")
 

From aa73309afbfe8e0cec347d1a49c0709e86338621 Mon Sep 17 00:00:00 2001
From: superstar54 <xingwang1991@gmail.com>
Date: Mon, 26 Jan 2026 15:19:04 +0100
Subject: [PATCH 3/3] Fix general_serializer

---
 src/aiida_pythonjob/data/serializer.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/aiida_pythonjob/data/serializer.py b/src/aiida_pythonjob/data/serializer.py
index 8b117c0..f52b743 100644
--- a/src/aiida_pythonjob/data/serializer.py
+++ b/src/aiida_pythonjob/data/serializer.py
@@ -112,7 +112,7 @@ def general_serializer(
     serializers = serializers or all_serializers
 
     # 1) If it is already an AiiDA node, just return it
-    if isinstance(data, orm.Data):
+    if isinstance(data, orm.Node):
         return data
     elif isinstance(data, common.extendeddicts.AttributeDict):
         # if the data is an AttributeDict, use it directly