solidstate/lib/solidstate/link/FilterLink.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',
    './Link',
    '../misc'
], function(ko, _, Link, misc) {
    'use strict';

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

    // FilterLink :: { String: Model -> String|Number } -> (Link -> Link)
    //
    // The same as the input link, but adds filters based on a dictionary
    // of input functions. It combines the values from all the models
    // into a single filter.
    //
    var FilterLink = function(filters) {
        filters || die('Missing required arg `filters` for FilterLink');

        return function(link) {
            link    || die('Missing required arg `link` for FilterLink');

            return new Link({ 
                resolve: function(sourceCollection) {
                    var target = link.resolve(sourceCollection);
                    
                    var targetData = c(function() {
                        var data = {};
                        _(filters).each(function(fn, key) {
                            var vals = _.chain(sourceCollection.models())
                                .values()
                                .map(u)
                                .map(fn)
                                .filter(function(v) { return _(v).isString() || _(v).isNumber(); }) 
                                .uniq()
                                .value()
                                .sort();
                            
                            if ( _(vals).isEmpty() ) vals = misc.NOFETCH;
                            
                            data[key] = vals;
                        });
                        
                        // And... danger / hardcoding for tastypie for now (can actually be easily expressed in the client code, but verbose)
                        data.limit = 0;
                        
                        return data;
                    }).extend({throttle: 1});
                    
                    return target.withFields({ data: targetData });
                }
            });
        };
    };

    return FilterLink;
});