Multiple associations in Sails.js

associations, javascript, node.js, sails.js

Solution

Sails handles the join table for you, so you don't need the `TagRelation` model at all:

// Post model
var Post = {
    title: 'string',
    body: 'string',
    tags: {
        collection: 'tag',
        via: 'posts',
        dominant: true // could be on either model, doesn't matter
    }
};

// Tag model
var Tag = {
    name: 'string',
    posts: {
        collection: 'post',
        via: 'tags'
    }
};

This way the blueprint `/post/1` will contain all its associated `tags`. See the association docs for more info - broken link fixed.

The `dominant:true` tag lets Sails know which side of an association to put the join table on, in case the two models are in different databases. We're working on making this optional when the two models are in the same database, but for now it has to be specified explicitly.

Problem

I'm currently playing around with associations in Sails.js beta (v 0.10.0-rc4). I'm trying to relate multiple databases into one result (using `sails-mysql`). The association looks like this `Post` -> `TagRelation` -> `Tag`. And I when I query the `Post` table, I want the returned object to include the associated `Tag` names. The models look something like this: ``` // Post model var Post = { title: 'string', body: 'string', tag_relations: { collection: 'TagRelation' via: 'post_id' } }; // Tag Relation model var TagRelation = { post_id: { model: 'Post' }, tag_id: { model: 'Tag' } }; // Tag model var Tag = { name: 'string', tag_relations: { collection: 'Tag', via: 'tag_id' } }; ``` Now, once I go to `http://localhost:1337/post/1` I'll get a JSON object with a `tag_relations` key, containing an array of `TagRelation` objects, but is there a way to get a list of actual `Tag` objects they are referring to instead? Or is there a better way to do this?

Original source