如何覆盖Django管理员更改表单中的字段值显示

I am wanting to override the value that is displayed for a field in the Django admin. The field contains XML and when viewing it in the admin I want to pretty-format it for easy readability. I know how to do reformatting on read and write of the field itself, but this is not what I want to do. I want the XML stored with whitespace stripped and I only want to reformat it when it is viewed in the admin change form.I am wanting to override the value that is disp