Way to define unique constraint for multiple columns on Associations?

[reumia]

I already know the way to defining when define models like this.

db.define('likes_user', {
  userId: {type: 'integer', unique: 'userId_targetId'},
  targetId: {type: 'integer', unique: 'userId_targetId'}
})

but i define those keys automatically when make associations.
so i want to know is there any ways for defining unique keys when make associations :(

here is my codes for associations. need helps!

LikesUser.hasOne('target', Users, {reverse: 'likes', field: 'targetId', mapsTo: 'target_id', required: true})
LikesUser.hasOne('user', Users, {reverse: 'likeUsers', field: 'userId', mapsTo: 'user_id', required: true})