In a model's Meta class, I define a unique_together. I have a ModelForm based on this model. When I call is_valid on this ModelForm, an error will automatically raised if unique_together validation fails. That's all good.
Now my problem is that I'm not satisfied with the default unique_together error message. I want to override it. How can I do that? For a field related error, I can easily do that by setting error_messages on the field parameters. But unique_together is a non field error. How can I override a non field error message?