extjs-gpl/examples/feed-viewer/app/rss/Proxy.js

GPL licensed version of Sencha Ext JS

/**
 * A data.Proxy implementation for loading select RSS Feeds directly from the google.api
 * in lieu of JSONP and or other cross-domain method
 */
Ext.define('FeedViewer.rss.Proxy', {
    extend: 'Ext.data.proxy.Server',
    requires: [
        'Ext.ux.google.Feeds'
    ],

    alias: 'proxy.googglerss',

    reader: {
        type: 'json',
        rootProperty: 'feed',
        messageProperty: 'status.message',
        successProperty: 'status.success'
    },

    isRssProxy: true,

    /**
     * Copy any sorters, filters etc into the params so they can be sent over the wire
     * @private
     */
    getParams: function (operation) {
       return {};
    },

    /**
     * Generates a url based on a given Ext.data.Request object. By default, ServerProxy's
     * buildUrl will add the
     * cache-buster param to the end of the url. Subclasses may need to perform additional modifications to the url.
     * @param {Ext.data.Request} request The request object
     * @return {String} The url
     */
    buildUrl: function (request) {
       var me = this,
           url = me.getUrl(request);

       //<debug>
       if (!url) {
           Ext.raise("You are using an RssProxy but have not supplied it with a url.");
       }
       //</debug>

       return url;
    },

    /**
     * @param {Ext.data.operation.Operation} operation The Ext.data.operation.Operation object
     * @param {Function} callback The callback function to call when the Operation has completed
     * @param {Object} scope The scope in which to execute the callback
     * @return {Ext.data.Request} request
     */
    doRequest: function (operation, callback, scope) {
        var me = this,
            request = me.buildRequest(operation),
            feed;

        //<debug>
        if (!operation.isReadOperation) {
           Ext.raise("The RssProxy only supports 'read' operations");
        }
        //</debug>

        request.setConfig({
            scope               : scope,
            callback            : callback
        });

        feed = request.feed = new google.feeds.Feed(request.getUrl());
        feed.setNumEntries( operation.getLimit() || 4);

        return me.sendRequest(request);
    },

    /**
     * Makes a Google Feeds Api request
     * @param {Ext.data.Request} request
     * @return {Ext.data.Request} request
     * @private
     */
    sendRequest: function (request) {
        var me = this,
            feed = request.feed,
            operation = request.getOperation();

        feed.setResultFormat( google.feeds.Feed.JSON_FORMAT );
        feed.includeHistoricalEntries();
        feed.load( Ext.Function.bind( me.createRequestCallback(request, operation), me ));

        me.lastRequest = request;
        return request;
    },

    /**
     * @param {Ext.data.Request} request The Request object
     * @param {Ext.data.operation.Operation} operation The Operation being executed
     * @return {Function} The callback function
     * @private
     */
    createRequestCallback: function (request, operation) {
        var me = this;

        return function(response) {
            if (request === me.lastRequest) {
                me.lastRequest = null;
            }

            // Normalize status for the reader and operation
            var status = Ext.apply(
                {message : ''},
                response.status,
                response.error
            );

            status.success = !response.error;
            response.status = status;

            me.processResponse( status.success, operation, request, response);
            me = request = operation = null;
        };
    },

    /**
     * Optional callback function which can be used to clean up after a request has completed.
     * @param {Ext.data.Request} request The Request object
     * @param {Boolean} success True if the request was successful
     * @protected
     * @template
     */
    afterRequest: function (request, success) {
        delete request.feed;
    }
});