Question

Thie is the source code in Django, when change the permission for a user named “xxx///\”, it will have an error, but in fact i don’t want to block this format username, so i want to overwrite the UserChangeForm class. Could you please tell me how to do this? Thanks!

class UserChangeForm(forms.ModelForm):
    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>."))

    def clean_password(self):
        return self.initial["password"]

    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')

I finally find the method,add this in the Admin.py

from django.contrib.auth.admin import UserAdmin
# overwrite the UserChangeForm
class UserChangeForm(forms.ModelForm):
    username = forms.RegexField(
        label=_("Username"), max_length=30, regex=r"^[a-zA-Z0-9@\.+-_\/\\]+$",
        help_text = _("Required. 30 characters or fewer. Letters, digits and "
                      "@/./+/-/_ only."),
        error_messages = {
            'invalid': _("This value may contain only letters, numbers and "
                         ".")})
UserAdmin.form = UserChangeForm

Thanks all the same

Answer 1

Your regex isn’t doing what you want. Find some tutorials on regex (google ‘Regex Tutorial’). Then I’d suggest getting some software to test regex (Regex Coach on windows is great).

I think the expression ^[a-zA-Z0-9@\.+-_\/\\]+$. Should do what you’re looking for. You’ll need to change your help and error text too – you’re actually accepting additional characters to the ones you say you’re accepting. Lastly, add a max_length field to match your existing help text.

class CustomChangeForm(forms.ModelForm):
    username = forms.RegexField(
        label=_("Username"), max_length=30, regex=r"^[a-zA-Z0-9@\.+-_\/\\]+$",
        help_text = _("Required. 30 characters or fewer. Letters, digits and "
                      "@.+-_/\ only."),
        error_messages = {
            'invalid': _("This value may contain only letters, numbers and "
                         "@.+-_/\ characters.")}),
        max_length=30)
        ....

EDIT

To override the UserChangeForm rewrite the class statement so your form inherits from UserChangeForm instead of ModelForm –

from django.contrib.auth.forms import UserChangeForm

class CustomChangeForm(UserChangeForm):
    username = forms.RexField(
        ...

Have a look at the docs for more information on inheritance with Django forms.