se implementa un esquema para modelar el xml

FossilOrigin-Name: e4de658f60fe8fcbb330923e14958a5d8f8e0e6395db4f992ec7da45062fa193

facho/model/fields/many2one.py

@@ -0,0 +1,35 @@
+from .field import Field
+
+class Many2One(Field):
+    def __init__(self, model, setter=None, namespace=None):
+        self.model = model
+        self.setter = setter
+        self.namespace = namespace
+
+    def __set_name__(self, owner, name):
+        self.name = name
+
+    def __get__(self, inst, cls):
+        if inst is None:
+            return self
+        assert self.name is not None
+        return inst._fields[self.name]
+        
+    def __set__(self, inst, value):
+        assert self.name is not None
+        class_model = self.model
+        inst_model = class_model()
+
+        self._set_namespace(inst_model, self.namespace,  inst.__namespace__)
+        inst._fields[self.name] = inst_model
+
+        # si hay setter manual se ejecuta
+        # de lo contrario se asigna como texto del elemento
+        setter = getattr(inst, self.setter or '', None)
+        if callable(setter):
+            setter(inst_model, value)
+        else:
+            inst_model._text = str(value)
+
+
+