diff --git a/core/cat/experimental/form/cat_form.py b/core/cat/experimental/form/cat_form.py
index 8c13061e..79a49df0 100644
--- a/core/cat/experimental/form/cat_form.py
+++ b/core/cat/experimental/form/cat_form.py
@@ -39,6 +39,9 @@ def __init__(self, cat) -> None:
     def cat(self):
         return self._cat
 
+    def model_getter(self):
+        return self.model_class
+
     def submit(self, form_data) -> str:
         raise NotImplementedError
 
@@ -124,7 +127,7 @@ def next(self):
         # If the state is INCOMPLETE, execute model update
         # (and change state based on validation result)
         if self._state == CatFormState.INCOMPLETE:
-            self._model = self.update()
+            self.update()
 
         # If state is COMPLETE, ask confirm (or execute action directly)
         if self._state == CatFormState.COMPLETE:
@@ -145,12 +148,11 @@ def update(self):
         json_details = self.sanitize(json_details)
 
         # model merge old and new
-        new_model = self._model | json_details
+        self._model = self._model | json_details
 
         # Validate new_details
-        new_model = self.validate(new_model)
+        self.validate()
 
-        return new_model
 
     def message(self):
         state_methods = {
@@ -219,7 +221,7 @@ def extraction_prompt(self):
         # JSON structure
         # BaseModel.__fields__['my_field'].type_
         JSON_structure = "{"
-        for field_name, field in self.model_class.model_fields.items():
+        for field_name, field in self.model_getter().model_fields.items():
             if field.description:
                 description = field.description
             else:
@@ -260,7 +262,7 @@ def sanitize(self, model):
         return model
 
     # Validate model
-    def validate(self, model):
+    def validate(self):
         self._missing_fields = []
         self._errors = []
 
@@ -268,7 +270,7 @@ def validate(self, model):
             # INFO TODO: In this case the optional fields are always ignored
 
             # Attempts to create the model object to update the default values and validate it
-            model = self.model_class(**model).model_dump(mode="json")
+            self.model_getter()(**self._model).model_dump(mode="json")
 
             # If model is valid change state to COMPLETE
             self._state = CatFormState.COMPLETE
@@ -281,9 +283,7 @@ def validate(self, model):
                     self._missing_fields.append(field_name)
                 else:
                     self._errors.append(f'{field_name}: {error_message["msg"]}')
-                    del model[field_name]
+                    del self._model[field_name]
 
             # Set state to INCOMPLETE
-            self._state = CatFormState.INCOMPLETE
-
-        return model
+            self._state = CatFormState.INCOMPLETE
\ No newline at end of file