Add support for validator disabling, fixes #75

docs/validators.rst

@@ -13,6 +13,7 @@ By default WTForms-Alchemy ModelForm assigns the following validators:
     * TimeRange validator if column is of type Time and info parameter has min or max arguments defined
     * Unique validator if column has a unique index
     * Length validator for String/Unicode columns with max length
+    * Optional validator for all nullable columns
 
 
 Unique validator
@@ -215,3 +216,15 @@ Here is the full list of configuration options you can use to override default v
 * time_range_validator
 
 * optional_validator
+
+
+Disabling validators
+--------------------
+
+You can disable certain validators by assigning them as `None`. Let's say you want to disable nullable columns having `Optional` validator. This can be achieved as follows::
+
+
+    class UserForm(ModelForm):
+        class Meta:
+            model = User
+            optional_validator = None

tests/test_validators.py

@@ -114,7 +114,7 @@ def test_not_nullable_fields_with_defaults_are_not_required(self):
         self.init(nullable=False, default=u'default')
         self.assert_not_required('test_column')
 
-    def test_assigns_not_nullable_integers_as_optional(self):
+    def test_assigns_nullable_integers_as_optional(self):
         self.init(sa.Integer, nullable=True)
         self.assert_optional('test_column')
 
@@ -226,6 +226,20 @@ class Meta:
         form = ModelTestForm()
         assert form.test_column.validators[1].message == 'Wrong length'
 
+    def test_override_optional_validator_as_none(self):
+        class ModelTest(self.base):
+            __tablename__ = 'model_test'
+            id = sa.Column(sa.Integer, primary_key=True)
+            test_column = sa.Column(sa.Boolean, nullable=True)
+
+        class ModelTestForm(ModelForm):
+            class Meta:
+                model = ModelTest
+                optional_validator = None
+
+        form = ModelTestForm()
+        assert form.test_column.validators == []
+
     def test_override_unique_validator(self):
         class ModelTest(self.base):
             __tablename__ = 'model_test'

wtforms_alchemy/generator.py

@@ -519,6 +519,9 @@ def required_validator(self, column):
     def get_validator(self, name, **kwargs):
         attr_name = '%s_validator' % name
         attr = getattr(self.meta, attr_name)
+        if attr is None:
+            return attr
+
         if inspect.ismethod(attr):
             return six.get_unbound_function(attr)(**kwargs)
         else: