falcor/lib/request/sendSetRequest.js

A JavaScript library for efficient data fetching.

var setJSONGraphs = require("./../set/setJSONGraphs");
var setPathValues = require("./../set/setPathValues");
var InvalidSourceError = require("./../errors/InvalidSourceError");

var emptyArray = [];
var emptyDisposable = {dispose: function() {}};

/**
 * A set request is not an object like GetRequest.  It simply only needs to
 * close over a couple values and its never batched together (at least not now).
 *
 * @private
 * @param {JSONGraphEnvelope} jsonGraph -
 * @param {Model} model -
 * @param {number} attemptCount
 * @param {Function} callback -
 */
var sendSetRequest = function(originalJsonGraph, model, attemptCount, callback) {
    var paths = originalJsonGraph.paths;
    var modelRoot = model._root;
    var errorSelector = modelRoot.errorSelector;
    var comparator = modelRoot.comparator;
    var boundPath = model._path;
    var resultingJsonGraphEnvelope;

    // This is analogous to GetRequest _merge / flushGetRequest
    // SetRequests are just considerably simplier.
    var setObservable;
    try {
        setObservable = model._source.
            set(originalJsonGraph, attemptCount);
    } catch (e) {
        callback(new InvalidSourceError());
        return emptyDisposable;
    }

    var disposable = setObservable.
        subscribe(function onNext(jsonGraphEnvelope) {
            // When disposed, no data is inserted into.  This can sync resolve
            // and if thats the case then its undefined.
            if (disposable && disposable.disposed) {
                return;
            }

            // onNext will insert all data into the model then save the json
            // envelope from the incoming result.
            model._path = emptyArray;

            var successfulPaths = setJSONGraphs(model, [{
                paths: paths,
                jsonGraph: jsonGraphEnvelope.jsonGraph
            }], null, errorSelector, comparator);

            jsonGraphEnvelope.paths = successfulPaths[1];

            model._path = boundPath;
            resultingJsonGraphEnvelope = jsonGraphEnvelope;
        }, function onError(dataSourceError) {
            if (disposable && disposable.disposed) {
                return;
            }
            model._path = emptyArray;

            setPathValues(model, paths.map(function(path) {
                return {
                    path: path,
                    value: dataSourceError
                };
            }), null, errorSelector, comparator);

            model._path = boundPath;

            callback(dataSourceError);
        }, function onCompleted() {
            callback(null, resultingJsonGraphEnvelope);
        });

    return disposable;
};

module.exports = sendSetRequest;