diff --git a/lib/xos-genx/xos-genx-tests/test_swagger.py b/lib/xos-genx/xos-genx-tests/test_swagger.py
index 1886a76..5b6d1f9 100644
--- a/lib/xos-genx/xos-genx-tests/test_swagger.py
+++ b/lib/xos-genx/xos-genx-tests/test_swagger.py
@@ -47,7 +47,7 @@
                  required manytoone node->Node:instances = 10 [db_index = True, null = False, blank = False];
                  required int32 numberCores = 11 [help_text = "Number of cores for instance", default = 0, null = False, db_index = False, blank = False];
                  required manytoone flavor->Flavor:instance = 12 [help_text = "Flavor of this instance", null = False, db_index = True, blank = False];
-                 optional string userData = 13 [help_text = "user_data passed to instance during creation", null = True, db_index = False, blank = True, varchar = True];
+                 optional string userData = 13 [help_text = "user_data passed to instance during creation", null = True, db_index = False, blank = True, text = True];
                  required string isolation = 14 [default = "vm", choices = "(('vm', 'Virtual Machine'), ('container', 'Container'), ('container_vm', 'Container In VM'))", max_length = 30, blank = False, null = False, db_index = False];
                  optional string volumes = 15 [help_text = "Comma-separated list of directories to expose to parent context", null = True, db_index = False, blank = True];
                  optional manytoone parent->Instance:instance = 16 [help_text = "Parent Instance for containers nested inside of VMs", null = True, db_index = True, blank = True];
diff --git a/lib/xos-genx/xos-genx-tests/test_validator.py b/lib/xos-genx/xos-genx-tests/test_validator.py
new file mode 100644
index 0000000..1a50082
--- /dev/null
+++ b/lib/xos-genx/xos-genx-tests/test_validator.py
@@ -0,0 +1,125 @@
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+from __future__ import absolute_import
+import unittest
+import os
+from xosgenx.validator import XProtoValidator
+from xosgenx.generator import XOSProcessor, XOSProcessorArgs
+from mock import patch
+import yaml
+
+# Generate other formats from xproto
+
+
+class XProtoValidatorTest(unittest.TestCase):
+    def test_suggested_max_length(self):
+        args = XOSProcessorArgs()
+        args.files = ["/tmp/testvalidator.xproto"]
+
+        open("/tmp/testvalidator.xproto", "w").write("""
+            option app_label = "test";
+
+            message Port (XOSBase){
+                required string foo = 1 [max_length=254];
+            }
+            """)
+        args.target = "modeldefs.xtarget"
+
+        with patch.object(XProtoValidator, "print_errors", autospec=True) as print_errors:
+            print_errors.return_value = None
+
+            output = XOSProcessor.process(args)
+
+            self.assertEqual(print_errors.call_count, 1)
+            validator = print_errors.call_args[0][0]
+
+            self.assertEqual(len(validator.errors), 1)
+            self.assertEqual(validator.errors[0]["severity"], "WARNING")
+            self.assertEqual(validator.errors[0]["message"], "max_length of 254 is close to suggested max_length of 256")
+
+    def test_max_length_okay(self):
+        args = XOSProcessorArgs()
+        args.files = ["/tmp/testvalidator.xproto"]
+
+        open("/tmp/testvalidator.xproto", "w").write("""
+            option app_label = "test";
+
+            message Port (XOSBase){
+                required string foo = 1 [max_length=256];
+            }
+            """)
+        args.target = "modeldefs.xtarget"
+
+        with patch.object(XProtoValidator, "print_errors", autospec=True) as print_errors:
+            print_errors.return_value = None
+
+            output = XOSProcessor.process(args)
+
+            self.assertEqual(print_errors.call_count, 0)
+
+    def test_max_length_zero(self):
+        args = XOSProcessorArgs()
+        args.files = ["/tmp/testvalidator.xproto"]
+
+        open("/tmp/testvalidator.xproto", "w").write("""
+            option app_label = "test";
+
+            message Port (XOSBase){
+                required string foo = 1 [max_length=0];
+            }
+            """)
+        args.target = "modeldefs.xtarget"
+
+        with patch.object(XProtoValidator, "print_errors", autospec=True) as print_errors:
+            print_errors.return_value = None
+
+            output = XOSProcessor.process(args)
+
+            self.assertEqual(print_errors.call_count, 1)
+            validator = print_errors.call_args[0][0]
+
+            self.assertEqual(len(validator.errors), 1)
+            self.assertEqual(validator.errors[0]["severity"], "ERROR")
+            self.assertEqual(validator.errors[0]["message"], "max_length should not be zero")
+
+
+    def test_charfield_missing_max_length(self):
+        args = XOSProcessorArgs()
+        args.files = ["/tmp/testvalidator.xproto"]
+
+        open("/tmp/testvalidator.xproto", "w").write("""
+            option app_label = "test";
+
+            message Port (XOSBase){
+                required string foo = 1 [];
+            }
+            """)
+        args.target = "modeldefs.xtarget"
+
+        with patch.object(XProtoValidator, "print_errors", autospec=True) as print_errors:
+            print_errors.return_value = None
+
+            output = XOSProcessor.process(args)
+
+            self.assertEqual(print_errors.call_count, 1)
+            validator = print_errors.call_args[0][0]
+
+            self.assertEqual(len(validator.errors), 1)
+            self.assertEqual(validator.errors[0]["severity"], "ERROR")
+            self.assertEqual(validator.errors[0]["message"], "String field should have a max_length or text=True")
+
+if __name__ == "__main__":
+    unittest.main()