solidstate/lib/solidstate/reference/JoinReference.js

An observable REST client for Javascript with a dramatically simple & fluent API.

if (typeof define !== 'function') { var define = require('amdefine')(module); }
define([ 
    'knockout',
    'underscore',
    './FilterReference'
], function(ko, _, FilterReference) {
    'use strict';

    var o = ko.observable,
        u = ko.utils.unwrapObservable,
        c = ko.computed,
        w = function(v) { return ko.isObservable(v) ? v : o(v); };

    // JoinReference
    //
    // A FilterReference where the `from` attribute and `to` attribute must match exactly.
    //
    var JoinReference = function(args) {
        var from = args.from || die('Missing required argument `from` in solidstate.JoinReference'),
            to   = args.to   || die('Missing required argument `to` in solidstate.JoinReference');

        return FilterReference(function(source, destination) { 
            _(source).has('attributes') || die('Model `source` passed to JoinReference missing attributes:' + source + '('+ui(source)+')');
            _(destination).has('attributes') || die('Model `destination` passed to JoinReference missing attributes:' + destination +'('+u(destination)+')');

            return u(source.attributes()[from]) === u(destination.attributes()[to]); 
        });
    };

    return JoinReference;
});