Question

I’m having a heckuva time understanding the documentation for Backbone-Relational; it’s not 100% clear on which relation to add things like includeInJSON. Probably best to describe my confusion by illustrating the structure I’m trying to create. I have a Venue model that has zero or more nested Address models (1:n relationship). The backend store is MongoDB, which can have embedded objects. I’d like to store it in this format:

{
    id: 12345,
    label: 'OPUS Cafe Bistro',
    addresses: [
        {
            type: 'mailing',
            address1: '#52 - 650 Duncan Ave',
            city: 'Penticton, BC'
        },
        {
            type: 'main',
            address1: '#106 - 1475 Fairview Rd',
            city: 'Penticton, BC'
        }
    ]
}

(Please ignore the ugly data structures; I’ve adjusted it for brevity.) Now I believe I set up the relationship between Venue and Address thusly:

var Venue = Backbone.RelationalModel.extend({
    relations: [
        {
            type: Backbone.HasMany,
            key: 'addresses',
            relatedModel: 'Address',
            includeInJSON: false,
            collectionType: 'Addresses',
            reverseRelation: {
                key: 'venue'
            }
        }
});

If I understand correctly, I set includeInJSON to false in order to prevent the Venue from being serialised into the venue key in Address, but under reverseRelation I leave includeInJSON blank in order to have the full Address (without a venue property) serialised as an array in the addresses property of the Venue – as per my hoped-for example. Correct?

By the same token, I’m trying to understand the same concept in relation to a join-style relationship. Consider that Venue now has an organisationID field:

/* venue in JSON format  */
{
    id: 12345,
    organisationID: 336,
    label: 'OPUS Cafe Bistro',
    addresses: []
}

/* and now for the organisation */
{
    id: 336,
    label: 'OPUS Entertainment Group'
}

Using the examples in the documentation, which seem to prefer the Backbone.HasMany relationship, I think that I’d have to set up Organisation thus:

var Organisation = Backbone.RelationalModel.extend({
    relations: [
        {
            type: Backbone:HasMany,
            key: 'venues',
            relatedModel: 'Venue',
            includeInJSON: Backbone.Model.prototype.idAttribute,
            collectionType: 'Venues',
            reverseRelation: {
                key: 'organisationID',
                includeInJSON: false
            }
        }
    ]
});

… which should serialise into the above example, right? (I.e., Venue grabs Organisation‘s id and inserts it into organisationID, and Organisation doesn’t serialise any list of Venues)

Thanks in advance for any help – looking forward to using this handy library, after clawing my eyeballs out trying to write my own relational glue for Backbone.js 🙂

Answer 1

(copying my answer from https://github.com/PaulUithol/Backbone-relational/issues/37 over here, so more people can hopefully find it)

I’m sure you’ve figured it out by now, sorry for replying so late, but just to be sure: options (like collectionType and includeInJSON) apply to the key that’s within the same object.

So, for your first example, you could write the relation as:

var Venue = Backbone.RelationalModel.extend({
    relations: [
        {
            type: Backbone.HasMany,
            key: 'addresses',
            relatedModel: 'Address',
            includeInJSON: true,
            collectionType: 'Addresses',
            reverseRelation: {
                key: 'venue',
                includeInJSON: 'id'
            }
        }
});

This will create a Venue that HasMany addresses. The addresses key for any given Venue uses the collectionType Addresses, and is fully serialized because includeInJSON is set to true (not that the default value for includeInJSON is also true; so if you don’t specifiy it, it will fully serialize a relation or reverseRelation).

The reverseRelation simply takes the same options, only applies them with respect to the venue key on any Address. In this case, it will only serialize the venue.id property for the venue it’s linked to.