generic csv validation filter

Author: aditbiswas1

filters/tests/test_validations.py

@@ -1,6 +1,7 @@
 import unittest
 from nose2.tools.such import helper
 from voluptuous import Invalid
+from django.core.exceptions import ImproperlyConfigured
 from filters import validations
 
 INT = 1
@@ -75,3 +76,27 @@ class CSVofIntegersTestCase(BaseValidationTestCase, unittest.TestCase):
         NON_INT_UNICODE, NON_ALNUM_STR, NON_ALNUM_UNICODE, NON_INT_CSV,
         INT, LONG
     ]
+
+class GenericSeparatedValidatorTestCase(unittest.TestCase):
+    def test_default_separator(self):
+        validator = validations.GenericSeparatedValidator(int)
+        self.assertEqual(validator('1,2,3'), [1,2,3])
+        self.assertRaises(Invalid, validator, 'a,b,c')
+        self.assertEqual(validator('1', [1]))
+
+    def test_custom_separator(self):
+        validator = validations.GenericSeparatedValidator(int, 'mm')
+        self.assertEqual(validator('1mm2mm3'), [1,2,3])
+        self.assertRaises(Invalid, validator, 'ammbmmc')
+        self.assertEqual(validator('1', [1]))
+
+    def test_custom_type(self):
+        validator = validations.GenericSeparatedValidator(
+                        validations.IntegerLike())
+        self.assertEqual(validator('1,2,3'), ['1','2','3'])
+        self.assertRaises(Invalid, validator, 'a,b,c')
+        self.assertEqual(validator('1', ['1']))
+
+    def test_invalid_separator(self):
+        self.assertRaises(ImproperlyConfigured, 
+            validations.GenericSeparatedValidator, 12)

filters/validations.py

@@ -3,6 +3,7 @@
 import numbers
 from voluptuous import Invalid
 from django.utils.dateparse import parse_datetime, parse_date
+from django.core.exceptions import ImproperlyConfigured
 
 # Forward compatibility with Python 3.x
 if sys.version_info.major == 3:
@@ -118,3 +119,68 @@ def fn(value):
                 '<{0}> is not a valid csv of integers'.format(value)
             )
     return fn
+
+
+
+class GenericSeparatedValidator(object):
+    '''
+    Creates list like validator for any voluptuous validation function
+    and any custom string separator.
+    Instance of the class should be passed to the schema like this:
+    >>> CSVofIntegers = GenericSeparatedValidator(int, ',')
+    >>> Schema({ "field": CSVofIntegers() })
+
+    >>> CSVofIntegers = GenericSeparatedValidator(int, ',')
+    >>> CSVofIntegers('1,2,3')
+    [1,2,3]
+
+    >>> WeirdSeparatedValidation = GenericSeparatedValidator(int, '^^')
+    >>> WeirdSeparatedValidation('1^^2^^3')
+    [1, 2, 3]
+
+    >>> CSVofIntegerLike = GenericSeparatedValidator(IntegerLike(), ',')
+    >>> CSVofIntegerLike('a,b,c')
+    Traceback (most recent call last):
+        ...
+    voluptuous.error.Invalid: <a,b,c> is not valid set of <IntegerLike>,\
+    Invalid input <a>; expected an integer
+    '''
+
+    def __init__(self, validation_function, separator=',', msg=None):
+        if not isinstance(separator, basestring):
+            raise ImproperlyConfigured(
+                'GenericSeparatedValidator separator \
+                 must be of type basestring'
+                )
+        self.separator = separator
+        self.validation_function = validation_function
+        self.msg = msg
+        if sys.version_info.major == 3:
+            self.value_type = validation_function.__qualname__.split('.')[0]
+        else:
+            self.value_type = validation_function.__name__
+
+    def __call__(self, value):
+        '''
+        Checks whether a value is list of given validation_function.
+        Returns list of validated values or just one valid value in
+        list if there is only one element in given CSV string.
+        '''
+        try:
+            if isinstance(value, basestring):
+                if self.separator in value:
+                    seperated_string_values =[item.strip() for item
+                        in value.split(self.separator)]
+                    values = [self.validation_function(item) for item
+                        in seperated_string_values]
+                else:
+                    values = [self.validation_function(value)]
+                return values
+            else:
+                raise ValueError
+        except (Invalid, ValueError) as e:
+            raise Invalid(self.msg or
+                ('<{0}> is not valid set of <{1}>, {2}'.format(
+                    value,
+                    self.value_type,
+                        e)))