Allowing the " - " character in usernames in the Django Admin interface

Question

In our webapp we needed to allow dashes "-" in our usernames. I've enabled that for the consumer signup process just fine with this regex r'^[\w-]+$'

How can I tell the admin app so that I can edit usernames in auth > users to allows the "-" character in usernames? Currently I am unable to edit any usernames with dashes in them as it will return a validation error on the username.

I'd like to try and avoid patching django directly if possible. I'm fairly new to programming but is this what I would use "subclassing" for?

Answer 1

This should be as simple as overriding the behavior of the User ModelAdmin class. In one of your apps, in admin.py include the following code.

from django.contrib import admin
from django import forms
from django.contrib.auth.models import User
from django.contrib.auth.admin import UserAdmin
from django.contrib.auth.forms import UserCreationForm, UserChangeForm

class MyUserCreationForm(UserCreationForm):
    username = forms.RegexField(
        label='Username', 
        max_length=30, 
        regex=r'^[\w-]+$',
        help_text = 'Required. 30 characters or fewer. Alphanumeric characters only (letters, digits, hyphens and underscores).',
        error_message = 'This value must contain only letters, numbers, hyphens and underscores.')

class MyUserChangeForm(UserChangeForm):
    username = forms.RegexField(
        label='Username', 
        max_length=30, 
        regex=r'^[\w-]+$',
        help_text = 'Required. 30 characters or fewer. Alphanumeric characters only (letters, digits, hyphens and underscores).',
        error_message = 'This value must contain only letters, numbers, hyphens and underscores.')

class MyUserAdmin(UserAdmin):
    form = MyUserChangeForm
    add_form = MyUserCreationForm

admin.site.unregister(User)
admin.site.register(User, MyUserAdmin)

Here's a little explanation.

The first class definition (MyUserCreationForm) is a subclass (yes your terminology is correct) of the UserCreationForm. This is the form that appears when you click "Add User" in the Django Admin site. All we are doing here is redefining the username field to use our improved, hyphen-accepting regex, and changing the helptext to reflect this.

The second class definition does the same, except for the UserChangeForm.

The final class definition is a subclass of UserAdmin, which is the ModelAdmin that the User model uses by default. Here we state that we want to use our new custom forms in the ModelAdmin.

Note that for each of these subclasses, we only change what we have to. The rest of the class will be inherited from its parent (UserCreationForm, UserChangeForm and UserAdmin respectively).

Finally, we perform the important step of registering the User model with the admin site. To do that we unregister the default UserAdmin, and then register with our improved MyUserAdmin class.

You'll find that the Django admin site is very easy to customize using these techniques, especially considering the admin site is just a regular Django app.