adding min & max length validation to the Text column type

cqlengine/columns.py

@@ -146,6 +146,23 @@ class Ascii(Column):
 class Text(Column):
     db_type = 'text'
 
+    def __init__(self, *args, **kwargs):
+        self.min_length = kwargs.pop('min_length', 1 if kwargs.get('required', True) else None)
+        self.max_length = kwargs.pop('max_length', None)
+        super(Text, self).__init__(*args, **kwargs)
+
+    def validate(self, value):
+        value = super(Text, self).validate(value)
+        if not isinstance(value, (basestring, bytearray)) and value is not None:
+            raise ValidationError('{} is not a string'.format(type(value)))
+        if self.max_length:
+            if len(value) > self.max_length:
+                raise ValidationError('{} is longer than {} characters'.format(self.column_name, self.max_length))
+        if self.min_length:
+            if len(value) < self.min_length:
+                raise ValidationError('{} is shorter than {} characters'.format(self.column_name, self.min_length))
+        return value
+
 class Integer(Column):
     db_type = 'int'
 

cqlengine/tests/columns/test_validation.py

@@ -1,6 +1,7 @@
 #tests the behavior of the column classes
 from datetime import datetime
 from decimal import Decimal as D
+from cqlengine import ValidationError
 
 from cqlengine.tests.base import BaseCassEngTestCase
 
@@ -94,6 +95,48 @@ class TestInteger(BaseCassEngTestCase):
         it = self.IntegerTest()
         it.validate()
 
+class TestText(BaseCassEngTestCase):
+
+    def test_min_length(self):
+        #min len defaults to 1
+        col = Text()
+
+        with self.assertRaises(ValidationError):
+            col.validate('')
+
+        col.validate('b')
+
+        #test not required defaults to 0
+        Text(required=False).validate('')
+
+        #test arbitrary lengths
+        Text(min_length=0).validate('')
+        Text(min_length=5).validate('blake')
+        Text(min_length=5).validate('blaketastic')
+        with self.assertRaises(ValidationError):
+            Text(min_length=6).validate('blake')
+
+    def test_max_length(self):
+
+        Text(max_length=5).validate('blake')
+        with self.assertRaises(ValidationError):
+            Text(max_length=5).validate('blaketastic')
+
+    def test_type_checking(self):
+        Text().validate('string')
+        Text().validate(u'unicode')
+        Text().validate(bytearray('bytearray'))
+
+        with self.assertRaises(ValidationError):
+            Text().validate(None)
+
+        with self.assertRaises(ValidationError):
+            Text().validate(5)
+
+        with self.assertRaises(ValidationError):
+            Text().validate(True)
+
+