diff --git a/assets/test_condition_empty.json b/assets/test_condition_empty.json
new file mode 100644
index 0000000..e4443b6
--- /dev/null
+++ b/assets/test_condition_empty.json
@@ -0,0 +1,14 @@
+{
+  "root": {
+    "variableType": "string",
+    "variableName": "temperatura",
+    "leafs": [
+      {
+        "id": "9c784070-9c7c-4c58-a35f-c5c73bdb66e8",
+        "value": "true",
+        "operator": "empty",
+        "leafs": [{ "result": true }]
+      }
+    ]
+  }
+}
diff --git a/assets/test_is_not_null.json b/assets/test_is_not_null.json
deleted file mode 100644
index 7c9e5df..0000000
--- a/assets/test_is_not_null.json
+++ /dev/null
@@ -1 +0,0 @@
-{"root":{"variableType":"string","variableName":"temperatura","leafs":[{"id":"9c784070-9c7c-4c58-a35f-c5c73bdb66e8","value":"None","operator":"is not","leafs":[{"result":true}]}]}}
\ No newline at end of file
diff --git a/jdtree/condition.py b/jdtree/condition.py
index 5564ed6..8c2107d 100644
--- a/jdtree/condition.py
+++ b/jdtree/condition.py
@@ -1,6 +1,6 @@
-from typing import List
+from typing import List, Any
 from numbers import Number
-
+from distutils.util import strtobool
 
 class Operator:
 
@@ -15,3 +15,13 @@ def not_between(self, x: Number, y: str):
         if len(list) != 2:
             return False
         return not eval(f'{list[0]} <= {x} <= {list[1]}')
+
+    def empty(self, x: Any, y: str):
+
+        if x and strtobool(y):
+            return True
+
+        if not x and not strtobool(y):
+            return True
+
+        return False
\ No newline at end of file
diff --git a/jdtree/jdt_engine.py b/jdtree/jdt_engine.py
index 5da2123..df99d95 100644
--- a/jdtree/jdt_engine.py
+++ b/jdtree/jdt_engine.py
@@ -94,11 +94,13 @@ def __compute_condition(
         except AttributeError:
             pass
         try:
-            eval_string = self.get_eval_string(variable_type, target_value, operator, variable_value)
+            eval_string = self.get_eval_string(
+                variable_type, target_value, operator, variable_value)
             print(eval_string)
             result = eval(eval_string)
             if result:
-                logging.info(f"TRUE {variable_type}('{target_value}') {operator} {variable_type}('{variable_value}')")
+                logging.info(
+                    f"TRUE {variable_type}('{target_value}') {operator} {variable_type}('{variable_value}')")
             return result
         except SyntaxError:
             raise UnsupportedOperation(f"{operator} not supported")
@@ -106,14 +108,9 @@ def __compute_condition(
     def get_eval_string(self, variable_type, target_value, operator, variable_value) -> str:
 
         variable_type_python = TO_PYTHON_TYPE.get(variable_type)
+        if variable_type == STRING_TYPE or variable_type == NUMBER_TYPE:
+            return f"{variable_type_python}('{target_value}') {operator} {variable_type_python}('{variable_value}')"
+        if variable_type == OBJECT_TYPE:
+            return f"{target_value} {operator} {variable_value}"
 
-        if variable_value == 'None':
-            variable_value = None
-
-        if variable_value:
-            variable_value = f"{variable_type_python}('{variable_value}')"
-
-        if target_value:
-            target_value = f"{variable_type_python}('{target_value}')"
-
-        return f"{target_value} {operator} {variable_value}"
+        raise Exception
diff --git a/setup.py b/setup.py
index 5389240..6744351 100644
--- a/setup.py
+++ b/setup.py
@@ -3,7 +3,7 @@
 setup(
     name='jdtree',
     packages=['jdtree'],
-    version='0.0.3',
+    version='0.0.4',
     description='Json Decision Table/Tree',
     author='Matteo Greco',
     license='MIT',
diff --git a/tests/test_jdtree.py b/tests/test_jdtree.py
index aab7be0..42880f3 100644
--- a/tests/test_jdtree.py
+++ b/tests/test_jdtree.py
@@ -12,8 +12,8 @@ def test_decision(self):
           })
         assert result == aspected_result
 
-    def test_decision_is_not_null(self):
-        tree = JDTEngine(file_path="assets/test_is_not_null.json")
+    def test_condition_empty(self):
+        tree = JDTEngine(file_path="assets/test_condition_empty.json")
         
         aspected_result = [{'result': True}]
         result = tree.decide(