diff --git a/facho/model/fields/function.py b/facho/model/fields/function.py
new file mode 100644
index 0000000..34e3195
--- /dev/null
+++ b/facho/model/fields/function.py
@@ -0,0 +1,24 @@
+from .field import Field
+from .model import Model
+
+class Function(Field):
+    def __init__(self, getter, setter=None, field=None):
+        self.field = field
+        self.getter = getter
+        self.setter = setter
+
+    def __get__(self, inst, cls):
+        if inst is None:
+            return self
+        assert self.name is not None
+
+        if self.field is None:
+            return self._call(inst, self.getter, self.name)
+        else:
+            obj = Model(self.field)
+            return self._call(inst, self.getter, self.name, obj)
+
+    def __set__(self, inst, value):
+        if self.setter is None:
+            return super().__set__(self.name, value)
+        self._call(inst, self.setter, self.name, value)
diff --git a/tests/test_model.py b/tests/test_model.py
index a4fd540..fa92e9f 100644
--- a/tests/test_model.py
+++ b/tests/test_model.py
@@ -217,13 +217,15 @@ def test_field_function_with_model():
     class Person(facho.model.Model):
         __name__ = 'Person'
 
-        hash = fields.Function('get_hash', field=fields.Model(Hash))
+        hash = fields.Function('get_hash', field=Hash)
 
         def get_hash(self, name, field):
             field.id = 'calculate'
+            return field
         
     person = Person()
-    assert '<Person><Hash id="calculate"/></Person>'
+    assert person.hash.id == 'calculate'
+    assert '<Person/>'
 
 def test_field_function():
     class Person(facho.model.Model):