BookshelfJS: How to apply BelongsToMany? - bookshelf.js

Question

I am confused how to apply BelongsToMany with Bookshelf.
Say, there is a Movie that BelongsToMany Genres, e.g.
"The Artist" has the genres "Comedy, Drama"
I have setup a join table called join_movies_genres that has FK movie_id and genre_id.
I try to fetch genres from a Movie with and without a through(...) definition. I get however undefined targets, similar to:
relatedData:
{ type: 'belongsToMany',
target:
{ [Function]
NotFoundError: [Function: ErrorCtor],
NoRowsUpdatedError: [Function: ErrorCtor],
NoRowsDeletedError: [Function: ErrorCtor] },
targetTableName: 'genres',
targetIdAttribute: 'id',
joinTableName: 'join_movies_genres',
foreignKey: { debug: true },
otherKey: undefined,
parentId: 1,
parentTableName: 'movies',
parentIdAttribute: 'id',
parentFk: 1,
throughTarget:
{ [Function]
NotFoundError: [Function: ErrorCtor],
NoRowsUpdatedError: [Function: ErrorCtor],
NoRowsDeletedError: [Function: ErrorCtor] },
throughTableName: 'join_movies_genres',
throughIdAttribute: 'id',
throughForeignKey: { debug: true } }
So, how would I approach setting up this relation? How can I enable a debug output?
The current state of the Model is:
var Movie = bookshelf.Model.extend({
tableName: 'movies',
genres: function() {
// return this.belongsToMany(Genre, 'join_movies_genres', 'movie_id', 'genre_id', {debug: true});
// return this.belongsToMany(Genre).through(JoinMovieGenre, 'movie_id', 'genre_id');
return this.belongsToMany(Genre, 'join_movies_genres', 'movie_id', 'genre_id').through(JoinMovieGenre, {debug: true});
}
});
var Genre = bookshelf.Model.extend({
tableName: 'genres'
});
new Movie({title: 'The Artist'}).fetch({debug: true}).then(function(m) {
console.log(m.toJSON());
console.log(m.genres())
})
A sandbox of this code is at https://github.com/mulderp/bookshelf-demo/tree/cli_migrations

Answer 1

Does this work?
var Movie = bookshelf.Model.extend({
tableName: 'movies',
genres: function() {
return this.belongsToMany(Genre, 'join_movies_genres', 'movie_id', 'genre_id');
}
});
var Genre = bookshelf.Model.extend({
tableName: 'genres'
});
new Movie({title: 'The Artist'}).fetch({withRelated:['genres']}).then(function(m) {
console.log(m.toJSON());
});