Message wording when unique_together rises

[Vlada Macek]

This one is IMHO not bound exactly to i18n as I think the msgid itself could be improved too.

db/models/base.py:991:

# unique_together
else:
    field_labels = [capfirst(opts.get_field(f).verbose_name) for f in unique_check]
    params['field_labels'] = six.text_type(get_text_list(field_labels, _('and')))
    return ValidationError(
        message=_("%(model_name)s with this %(field_labels)s already exists."),
        code='unique_together',
        params=params,
    )

For single field_label (one unique field constraint) there is a different msgid.

This one is used for the unique_together constraint so I'd expect 'these ... exist' or my favorite 'this combination of fields ... exists' would be better.

[Tim Graham]

I think the current version makes sense, e.g. "Book with this Title and Author already exists.".

As for your alternative suggestions:

"Book with these Title and Author exist." isn't correct.

"Book with this combination of Title and Author exists." seems okay, but I'm not sure it's much of an upgrade over the existing text.