Add value not empty string field validator

modularodm/validators/__init__.py

@@ -159,3 +159,15 @@ class MaxLengthValidator(BaseValidator):
     clean = lambda self, x: len(x)
     message = 'Ensure this value has length of at most {limit_value} (it has length {show_value}).'
     code = 'max_length'
+
+
+class ValueNotEmptyValidator(BaseValidator):
+
+    compare = lambda self, a, b: a == b
+    clean = lambda self, x: x.strip()
+    message = 'Ensure this value is not empty.'
+    code = 'not_empty'
+
+    def __init__(self):
+        self.limit_value = ''
+        super(ValueNotEmptyValidator, self).__init__(self.limit_value)

tests/validators/test_iterable_validators.py

@@ -1,7 +1,7 @@
 from modularodm import StoredObject
 from modularodm.exceptions import ValidationValueError
 from modularodm.fields import IntegerField, StringField
-from modularodm.validators import MaxLengthValidator, MinLengthValidator
+from modularodm.validators import MaxLengthValidator, MinLengthValidator, ValueNotEmptyValidator
 
 from tests.base import ModularOdmTestCase
 
@@ -18,6 +18,10 @@ class Foo(StoredObject):
                 list=False,
                 validate=[MinLengthValidator(5), ]
             )
+            test_field_empty = StringField(
+                list=False,
+                validate=[ValueNotEmptyValidator(), ]
+            )
         self.test_object = Foo(_id=0)
         return Foo,
 
@@ -39,6 +43,15 @@ def test_min_length_string_validator(self):
         self.test_object.test_field_min = 'abcdefg'
         self.test_object.save()
 
+    def test_value_not_empty_string_validator(self):
+
+        self.test_object.test_field_empty = ''
+        with self.assertRaises(ValidationValueError):
+            self.test_object.save()
+
+        self.test_object.test_field_empty = 'not empty'
+        self.test_object.save()
+
 
 class ListValidatorTestCase(ModularOdmTestCase):