attach with additional attributes

[vjpr]

When I call attach I generally want to be able to set other attributes on the M2M relation.

A common example might be a timestamp.

Something like collection.belongsToMany(db.Models.Link).attach(link, {archived: false})

I'd also like to be able to set defaults and methods for the M2M relation.

class CollectionsLinks extends Bookshelf.Model
  defaults:
    archived: false

I found the following which seems to indicate you can't pass in a model and additional params - I'd have to create a hash myself.

      // If the item is an object, it's either a model
      // that we're looking to attach to this model, or
      // a hash of attributes to set in the relation.
      if (_.isObject(item)) {
        if (item instanceof Model) {
          data[relatedData.foreignKey] = item.id;
        } else {
          _.extend(data, item);
        }
      } else if (item) {
        data[relatedData.foreignKey] = item;
      }

Also the comments for belongsToMany say:

The joinTableName may be replaced with another object, will serve as the joining model.

I expected to be able to pass a Bookshelf.Model, whose defaults would be set on attach, as well as timestamps, etc.

Examples of using many to many relations with additional attrs on the join table would be helpful.

[vjpr]

At the moment I'm just creating a join table model like so:

class Collection
  addLink: (link) =>
      cl = db.Models.CollectionLink.forge
        collectionId: @id
        linkId: link.id
        order: 0
      cl.save()

[tgriesser]

So I think I intended to be able to pass a model as a joinTableName but hadn't quite gotten there yet... If you want to try to work out an implementation/tests for it as a PR, that'd be great...I think the issue may have been with the need for a composite key based on the foreignKey & otherKey but also potentially allowing an idAttribute id... I'm not sure, I'll take out that comment for now so it's not confusing.

Right now you can do this:

collection.belongsToMany(db.Models.Link).attach(link.attributes)

And the object that is set as the attributes will be saved with additional columns, but I realize that doesn't help with wanting a model/methods/timestamps on the join table... I'll think a bit more about this one.

[tgriesser]

Oh... I know what I was going to do here - the equivalent of ActiveRecord's hasMany :through - where you could do

links: function() {
   return this.hasMany(Links, CollectionsLinks);
}

And then you'd have a CollectionsLinks model to work with for the joining table... Didn't quite work through the specifics, including how you'd access the join model or how the the fetch/eager loading on that would work... Does that make sense though?

[vjpr]

Yep that makes sense.

[tgriesser]

So @vjpr - this is sort of in the works. With 0.3.0 I added .belongsToMany(Model).through(OtherModel) which works well for retrieval, but I'm still working out how attaching & working with the OtherModel happens. I'll keep you posted when I make progress on this one.

[mistakia]

Hey, just wondering if there's an update on how to attach relations with a join model/table with additional attributes (timestamps, etc)?

[ErisDS]

I ended up here with the same question after searching 😉, I then found the following hints, which I thought it would be helpful to post here:

• Example on stackoverflow showing this is working now: http://stackoverflow.com/a/22153459/1808480
• Docs on with/update Pivot http://bookshelfjs.org/#Model-withPivot
• Related discussion Updating a record in a joining table #134

[rhys-vdw]

Hi @ErisDS. Thanks for pointing this out. I'll try to update the docs soon.