Fixed #20784 -- Added inverse_match parameter to RegexValidator.

django/core/validators.py

@@ -20,14 +20,17 @@ class RegexValidator(object):
     regex = ''
     message = _('Enter a valid value.')
     code = 'invalid'
+    inverse_match = False
 
-    def __init__(self, regex=None, message=None, code=None):
+    def __init__(self, regex=None, message=None, code=None, inverse_match=None):
         if regex is not None:
             self.regex = regex
         if message is not None:
             self.message = message
         if code is not None:
             self.code = code
+        if inverse_match is not None:
+            self.inverse_match = inverse_match
 
         # Compile the regex if it was not passed pre-compiled.
         if isinstance(self.regex, six.string_types):
@@ -35,9 +38,11 @@ class RegexValidator(object):
 
     def __call__(self, value):
         """
-        Validates that the input matches the regular expression.
+        Validates that the input matches the regular expression
+        if inverse_match is False, otherwise raises ValidationError.
         """
-        if not self.regex.search(force_text(value)):
+        if not (self.inverse_match is not bool(self.regex.search(
+                force_text(value)))):
             raise ValidationError(self.message, code=self.code)
 
     def __eq__(self, other):

docs/ref/validators.txt

@@ -59,20 +59,22 @@ to, or in lieu of custom ``field.clean()`` methods.
 
 ``RegexValidator``
 ------------------
-.. class:: RegexValidator([regex=None, message=None, code=None])
+.. class:: RegexValidator([regex=None, message=None, code=None, inverse_match=None])
 
     :param regex: If not ``None``, overrides :attr:`regex`. Can be a regular
         expression string or a pre-compiled regular expression.
     :param message: If not ``None``, overrides :attr:`.message`.
     :param code: If not ``None``, overrides :attr:`code`.
+    :param inverse_match: If not ``None``, overrides :attr:`inverse_match`.
 
     .. attribute:: regex
 
         The regular expression pattern to search for the provided ``value``,
         or a pre-compiled regular expression. Raises a
         :exc:`~django.core.exceptions.ValidationError` with :attr:`message`
-        and :attr:`code` if no match is found. By default, matches any string
+        and :attr:`code` if :attr:`inverse_match` is ``False`` and a match is
-        (including an empty string).
+        found, or if :attr:`inverse_match` is ``True`` and a match is not found.
+        By default, matches any string (including an empty string).
 
     .. attribute:: message
 
@@ -85,6 +87,12 @@ to, or in lieu of custom ``field.clean()`` methods.
         The error code used by :exc:`~django.core.exceptions.ValidationError`
         if validation fails. Defaults to ``"invalid"``.
 
+    .. attribute:: inverse_match
+
+        .. versionadded:: 1.7
+
+        The match mode for :attr:`regex`. Defaults to ``False``.
+
 ``URLValidator``
 ----------------
 .. class:: URLValidator([schemes=None, regex=None, message=None, code=None])

docs/releases/1.7.txt

@@ -697,6 +697,12 @@ Tests
 Validators
 ^^^^^^^^^^
 
+* :class:`~django.core.validators.RegexValidator` now accepts an optional
+  Boolean :attr:`~django.core.validators.RegexValidator.inverse_match` argument
+  which determines if the :exc:`~django.core.exceptions.ValidationError` should
+  be raised when the regular expression pattern matches (``True``) or does not
+  match (``False``, by default) the provided ``value``.
+
 * :class:`~django.core.validators.URLValidator` now accepts an optional
   ``schemes`` argument which allows customization of the accepted URI schemes
   (instead of the defaults ``http(s)`` and ``ftp(s)``).

tests/validators/tests.py

@@ -187,6 +187,10 @@ TEST_DATA = (
 
     (RegexValidator('x'), 'y', ValidationError),
     (RegexValidator(re.compile('x')), 'y', ValidationError),
+    (RegexValidator('x', inverse_match=True), 'y', None),
+    (RegexValidator(re.compile('x'), inverse_match=True), 'y', None),
+    (RegexValidator('x', inverse_match=True), 'x', ValidationError),
+    (RegexValidator(re.compile('x'), inverse_match=True), 'x', ValidationError),
 )