Primary key unique constraint inherited on tanslation table

[thanegill]

When a model has a primary key unique constraint the child class translation table inherits this constraint, this then make the the translation table only able to hold one translation for each key.

Example:

class Message(Translatable, db.Model):
    __translatable__ = {
            'locales': ['en', 'es'],
            'fallback_locale': 'en',
        }
    key = db.Column(db.String(64), primary_key=True, nullable=False, unique=True)

class MessageTranslation(translation_base(Message)):
    __tablename__ = 'message_translation'
   text = db.Column(db.UnicodeText)

for locale in ['en', 'es']:
    message_translation = MessageTranslation(
            key='example_key',
            locale=locale,
            text='text',
        )
    db.session.add(message_translation)