Use snipt registration form, block emails

urls.py

@@ -1,7 +1,7 @@
 from views import amazon_search, amazon_image, lexers, pro_signup, sitemap, tags, pro_signup_complete
 from django.conf.urls.defaults import include, patterns, url
 from django.views.generic.simple import direct_to_template
-from registration.forms import RegistrationFormUniqueEmail
+from utils.forms import SniptRegistrationForm
 from django.http import HttpResponseRedirect
 from django.contrib import admin
 from snipts.views import search
@@ -53,7 +53,7 @@ urlpatterns = patterns('',
     url(r'^signup/$',
         'registration.views.register', {
             'backend': 'registration.backends.default.DefaultBackend',
-            'form_class': RegistrationFormUniqueEmail,
+            'form_class': SniptRegistrationForm,
         },
         name='registration_register'),
     url(r'', include('registration.backends.default.urls')),

utils/forms.py

@@ -0,0 +1,41 @@
+from django.utils.translation import ugettext_lazy as _
+from registration.forms import RegistrationForm
+from django.contrib.auth.models import User
+from django import forms
+
+
+class SniptRegistrationForm(RegistrationForm):
+    """
+    Subclass of ``RegistrationForm`` which enforces uniqueness of
+    email addresses.
+    
+    """
+    def clean_username(self):
+        """
+        Validate that the username is alphanumeric and is not already
+        in use.
+        
+        """
+        existing = User.objects.filter(username__iexact=self.cleaned_data['username'])
+        if existing.exists():
+            raise forms.ValidationError(_("A user with that username already exists."))
+
+        elif '@' in self.cleaned_data['username']:
+            raise forms.ValidationError(_("Cannot have '@' in username."))
+        elif '.' in self.cleaned_data['username']:
+            raise forms.ValidationError(_("Cannot have '.' in username."))
+        elif '+' in self.cleaned_data['username']:
+            raise forms.ValidationError(_("Cannot have '+' in username."))
+
+        else:
+            return self.cleaned_data['username']
+
+    def clean_email(self):
+        """
+        Validate that the supplied email address is unique for the
+        site.
+        
+        """
+        if User.objects.filter(email__iexact=self.cleaned_data['email']):
+            raise forms.ValidationError(_("This email address is already in use. Please supply a different email address."))
+        return self.cleaned_data['email']