text: from django.utils.translation import ugettext_lazy as _
  from django import forms
  from django.contrib.auth.forms import ReadOnlyPasswordHashField
  
  from mongoengine.django.auth import User
  
  from mongodbforms import DocumentForm
  
  class UserCreationForm(DocumentForm):
      """
      A form that creates a user, with no privileges, from the given username and
      password.
      """
      error_messages = {
          'duplicate_username': _("A user with that username already exists."),
          'password_mismatch': _("The two password fields didn't match."),
      }
      username = forms.RegexField(label=_("Username"), max_length=30,
          regex=r'^[\w.@+-]+$',
          help_text=_("Required. 30 characters or fewer. Letters, digits and "
                        "@/./+/-/_ only."),
          error_messages={
              'invalid': _("This value may contain only letters, numbers and "
                           "@/./+/-/_ characters.")})
      password1 = forms.CharField(label=_("Password"),
          widget=forms.PasswordInput)
      password2 = forms.CharField(label=_("Password confirmation"),
          widget=forms.PasswordInput,
          help_text=_("Enter the same password as above, for verification."))
  
      class Meta:
          model = User
          fields = ("username",)
  
      def clean_username(self):
          # Since User.username is unique, this check is redundant,
          # but it sets a nicer error message than the ORM. See #13147.
          username = self.cleaned_data["username"]
          try:
              User.objects.get(username=username)
          except User.DoesNotExist:
              return username
          raise forms.ValidationError(
              self.error_messages['duplicate_username'],
              code='duplicate_username',
          )
  
      def clean_password2(self):
          password1 = self.cleaned_data.get("password1")
          password2 = self.cleaned_data.get("password2")
          if password1 and password2 and password1 != password2:
              raise forms.ValidationError(
                  self.error_messages['password_mismatch'],
                  code='password_mismatch',
              )
          return password2
  
      def save(self, commit=True):
          user = super(UserCreationForm, self).save(commit=False)
          self.instance = user.set_password(self.cleaned_data["password1"])
          return self.instance
          
          
  class UserChangeForm(DocumentForm):
      username = forms.RegexField(
          label=_("Username"), max_length=30, regex=r"^[\w.@+-]+$",
          help_text=_("Required. 30 characters or fewer. Letters, digits and "
                        "@/./+/-/_ only."),
          error_messages={
              'invalid': _("This value may contain only letters, numbers and "
                           "@/./+/-/_ characters.")})
      password = ReadOnlyPasswordHashField(label=_("Password"),
          help_text=_("Raw passwords are not stored, so there is no way to see "
                      "this user's password, but you can change the password "
                      "using <a href=\"password/\">this form</a>."))
  
      class Meta:
          model = User
  
      def __init__(self, *args, **kwargs):
          super(UserChangeForm, self).__init__(*args, **kwargs)
          f = self.fields.get('user_permissions', None)
          if f is not None:
              f.queryset = f.queryset.select_related('content_type')
  
      def clean_password(self):
          # Regardless of what the user provides, return the initial value.
          # This is done here, rather than on the field, because the
          # field does not have access to the initial value
          return self.initial["password"]
          
      def clean_email(self):
          email = self.cleaned_data.get("email")
          if email == '':
              return None
          return email
  