Fixed #28201 -- Added ProhibitNullCharactersValidator and used it on CharField form field.

django/core/validators.py

@@ -503,3 +503,27 @@ def get_available_image_extensions():
 validate_image_file_extension = FileExtensionValidator(
     allowed_extensions=get_available_image_extensions(),
 )
+
+
+@deconstructible
+class ProhibitNullCharactersValidator:
+    """Validate that the string doesn't contain the null character."""
+    message = _('Null characters are not allowed.')
+    code = 'null_characters_not_allowed'
+
+    def __init__(self, message=None, code=None):
+        if message is not None:
+            self.message = message
+        if code is not None:
+            self.code = code
+
+    def __call__(self, value):
+        if '\x00' in str(value):
+            raise ValidationError(self.message, code=self.code)
+
+    def __eq__(self, other):
+        return (
+            isinstance(other, self.__class__) and
+            self.message == other.message and
+            self.code == other.code
+        )