switch to decorator used to register property_fields and save it on Meta inner class to expose to cloned fastapi models

ormar/decorators/__init__.py

@@ -0,0 +1,5 @@
+from ormar.decorators.property_field import property_field
+
+__all__ = [
+    "property_field",
+]

ormar/decorators/property_field.py

@@ -0,0 +1,19 @@
+import inspect
+from collections.abc import Callable
+from typing import Union
+
+from ormar.exceptions import ModelDefinitionError
+
+
+def property_field(func: Callable) -> Union[property, Callable]:
+    if isinstance(func, property):  # pragma: no cover
+        func.fget.__property_field__ = True
+    else:
+        arguments = list(inspect.signature(func).parameters.keys())
+        if len(arguments) > 1 or arguments[0] != "self":
+            raise ModelDefinitionError(
+                "property_field decorator can be used "
+                "only on class methods with no arguments"
+            )
+        func.__dict__["__property_field__"] = True
+    return func