    /**
     * The JSON Reader is used by a Proxy to read a server response that is sent back in JSON format. This usually happens
     * as a result of loading a Store - for example we might create something like this:
     *
     *     Ext.define('User', {
     *         extend: 'Ext.data.Model',
     *         fields: ['id', 'name', 'email']
     *     });
     *
     *     var store = Ext.create('Ext.data.Store', {
     *         model: 'User',
     *         proxy: {
     *             type: 'ajax',
     *             url : 'users.json',
     *             reader: {
     *                 type: 'json'
     *             }
     *         }
     *     });
     *
     * The example above creates a 'User' model. Models are explained in the {@link Ext.data.Model Model} docs if you're not
     * already familiar with them.
     *
     * We created the simplest type of JSON Reader possible by simply telling our {@link Ext.data.Store Store}'s {@link
     * Ext.data.proxy.Proxy Proxy} that we want a JSON Reader. The Store automatically passes the configured model to the
     * Store, so it is as if we passed this instead:
     *
     *     reader: {
     *         type : 'json',
     *         model: 'User'
     *     }
     *
     * The reader we set up is ready to read data from our server - at the moment it will accept a response like this:
     *
     *     [
     *         {
     *             "id": 1,
     *             "name": "Ed Spencer",
     *             "email": "ed@sencha.com"
     *         },
     *         {
     *             "id": 2,
     *             "name": "Abe Elias",
     *             "email": "abe@sencha.com"
     *         }
     *     ]
     *
     * ## Reading other JSON formats
     *
     * If you already have your JSON format defined and it doesn't look quite like what we have above, you can usually pass
     * JsonReader a couple of configuration options to make it parse your format. For example, we can use the
     * {@link #rootProperty} configuration to parse data that comes back like this:
     *
     *     {
     *         "users": [
     *            {
     *                "id": 1,
     *                "name": "Ed Spencer",
     *                "email": "ed@sencha.com"
     *            },
     *            {
     *                "id": 2,
     *                "name": "Abe Elias",
     *                "email": "abe@sencha.com"
     *            }
     *         ]
     *     }
     *
     * To parse this we just pass in a {@link #rootProperty} configuration that matches the 'users' above:
     *
     *     reader: {
     *         type: 'json',
     *         rootProperty: 'users'
     *     }
     *
     * Sometimes the JSON structure is even more complicated. Document databases like CouchDB often provide metadata around
     * each record inside a nested structure like this:
     *
     *     {
     *         "total": 122,
     *         "offset": 0,
     *         "users": [
     *             {
     *                 "id": "ed-spencer-1",
     *                 "value": 1,
     *                 "user": {
     *                     "id": 1,
     *                     "name": "Ed Spencer",
     *                     "email": "ed@sencha.com"
     *                 }
     *             }
     *         ]
     *     }
     *
     * In the case above the record data is nested an additional level inside the "users" array as each "user" item has
     * additional metadata surrounding it ('id' and 'value' in this case). To parse data out of each "user" item in the JSON
     * above we need to specify the {@link #record} configuration like this:
     *
     *     reader: {
     *         type: 'json',
     *         record: 'user',
     *         rootProperty: 'users'
     *     }
     *
     * ## Response MetaData
     *
     * The server can return metadata in its response, in addition to the record data, that describe attributes
     * of the data set itself or are used to reconfigure the Reader. To pass metadata in the response you simply
     * add a `metaData` attribute to the root of the response data. The metaData attribute can contain anything,
     * but supports a specific set of properties that are handled by the Reader if they are present:
     *
     * - {@link #idProperty}: property name for the primary key field of the data
     * - {@link #rootProperty}: the property name of the root response node containing the record data
     * - {@link #totalProperty}: property name for the total number of records in the data
     * - {@link #successProperty}: property name for the success status of the response
     * - {@link #messageProperty}: property name for an optional response message
     * - {@link Ext.data.Model#cfg-fields fields}: Config used to reconfigure the Model's fields before converting the
     *   response data into records
     *
     * An initial Reader configuration containing all of these properties might look like this ("fields" would be
     * included in the Model definition, not shown):
     *
     *     reader: {
     *         type: 'json',
     *         idProperty: 'id',
     *         rootProperty: 'root',
     *         totalProperty: 'total',
     *         successProperty: 'success',
     *         messageProperty: 'message'
     *     }
     *
     * If you were to pass a response object containing attributes different from those initially defined above, you could
     * use the `metaData` attribute to reconifgure the Reader on the fly. For example:
     *
     *     {
     *         "count": 1,
     *         "ok": true,
     *         "msg": "Users found",
     *         "users": [{
     *             "userId": 123,
     *             "name": "Ed Spencer",
     *             "email": "ed@sencha.com"
     *         }],
     *         "metaData": {
     *             "idProperty": 'userId',
     *             "rootProperty": "users",
     *             "totalProperty": 'count',
     *             "successProperty": 'ok',
     *             "messageProperty": 'msg'
     *         }
     *     }
     *
     * You can also place any other arbitrary data you need into the `metaData` attribute which will be ignored by the Reader,
     * but will be accessible via the Reader's {@link #metaData} property. Application code can then process the passed
     * metadata in any way it chooses.
     *
     * A simple example for how this can be used would be customizing the fields for a Model that is bound to a grid. By passing
     * the `fields` property the Model will be automatically updated by the Reader internally, but that change will not be
     * reflected automatically in the grid unless you also update the column configuration. You could do this manually, or you
     * could simply pass a standard grid column config object as part of the `metaData` attribute
     * and then pass that along to the grid. Here's a very simple example for how that could be accomplished:
     *
     *     // response format:
     *     {
     *         ...
     *         "metaData": {
     *             "fields": [
     *                 { "name": "userId", "type": "int" },
     *                 { "name": "name", "type": "string" },
     *                 { "name": "birthday", "type": "date", "dateFormat": "Y-j-m" },
     *             ],
     *             "columns": [
     *                 { "text": "User ID", "dataIndex": "userId", "width": 40 },
     *                 { "text": "User Name", "dataIndex": "name", "flex": 1 },
     *                 { "text": "Birthday", "dataIndex": "birthday", "flex": 1, "format": 'Y-j-m', "xtype": "datecolumn" }
     *             ]
     *         }
     *     }
     *
     * The Reader will automatically read the meta fields config and rebuild the Model based on the new fields, but to handle
     * the new column configuration you would need to handle the metadata within the application code. This is done simply enough
     * by handling the metachange event on either the store or the proxy, e.g.:
     *
     *     var store = Ext.create('Ext.data.Store', {
     *         ...
     *         listeners: {
     *             'metachange': function(store, meta) {
     *                 myGrid.reconfigure(store, meta.columns);
     *             }
     *         }
     *     });
     */
    Ext.define('Ext.data.reader.Json', {
        extend: 'Ext.data.reader.Reader',
        alternateClassName: 'Ext.data.JsonReader',
        alias : 'reader.json',

        config: {
            /**
             * @cfg {String} [record=null]
             * The optional location within the JSON response that the record data itself can be found at. See the
             * JsonReader intro docs for more details. This is not often needed.
             */
            record: null,

            /**
             * @cfg {Boolean} [useSimpleAccessors=false]
             * True to ensure that field names/mappings are treated as literals when reading values. Defalts to false. For
             * example, by default, using the mapping "foo.bar.baz" will try and read a property foo from the root, then a
             * property bar from foo, then a property baz from bar. Setting the simple accessors to true will read the
             * property with the name "foo.bar.baz" direct from the root object.
             */
            useSimpleAccessors: false
        },

        //inherit docs
        getResponseData: function(response) {
            // Handle an XMLHttpRequest object
            if (response && response.responseText) {
                response = response.responseText;
            }

            // Handle the case where data has already been decoded
            if (typeof response !== 'string') {
                return response;
            }

            var data;
            try {
                data = Ext.decode(response);
            }
            catch (ex) {
                /**
                 * @event exception Fires whenever the reader is unable to parse a response.
                 * @param {Ext.data.reader.Xml} reader A reference to this reader
                 * @param {XMLHttpRequest} response The XMLHttpRequest response object.
                 * @param {String} error The error message.
                 */
                this.fireEvent('exception', this, response, 'Unable to parse the JSON returned by the server: ' + ex.toString());

                Ext.Logger.error('Unable to parse the JSON returned by the server: ' + ex.toString());
            }
            //<debug>
            if (!data) {
                this.fireEvent('exception', this, response, 'JSON object not found');

                Ext.Logger.error('JSON object not found');
            }
            //</debug>

            return data;
        },

        // inherit docs
        buildExtractors: function() {
            var me = this,
                root = me.getRootProperty();

            me.callParent(arguments);

            if (root) {
                me.rootAccessor = me.createAccessor(root);
            } else {
                delete me.rootAccessor;
            }
        },

        /**
         * We create this method because root is now a config so getRoot is already defined, but in the old
         * data package getRoot was passed a data argument and it would return the data inside of the root
         * property. This method handles both cases.
         * @param data (Optional)
         * @return {String/Object} Returns the config root value if this method was called without passing
         * data. Else it returns the object in the data bound to the root.
         * @private
         */
        getRoot: function(data) {
            var fieldsCollection = this.getModel().getFields();

            /*
             * We check here whether the fields are dirty since the last read.
             * This works around an issue when a Model is used for both a Tree and another
             * source, because the tree decorates the model with extra fields and it causes
             * issues because the readers aren't notified.
             */
            if (fieldsCollection.isDirty) {
                this.buildExtractors(true);
                delete fieldsCollection.isDirty;
            }

            if (this.rootAccessor) {
                return this.rootAccessor.call(this, data);
            } else {
                return data;
            }
        },

        /**
         * @private
         * We're just preparing the data for the superclass by pulling out the record objects we want. If a {@link #record}
         * was specified we have to pull those out of the larger JSON object, which is most of what this function is doing
         * @param {Object} root The JSON root node
         * @return {Ext.data.Model[]} The records
         */
        extractData: function(root) {
            var recordName = this.getRecord(),
                data = [],
                length, i;

            if (recordName) {
                length = root.length;

                if (!length && Ext.isObject(root)) {
                    length = 1;
                    root = [root];
                }

                for (i = 0; i < length; i++) {
                    data[i] = root[i][recordName];
                }
            } else {
                data = root;
            }
            return this.callParent([data]);
        },

        /**
         * @private
         * Returns an accessor function for the given property string. Gives support for properties such as the following:
         * 'someProperty'
         * 'some.property'
         * 'some["property"]'
         * This is used by buildExtractors to create optimized extractor functions when casting raw data into model instances.
         */
        createAccessor: function() {
            var re = /[\[\.]/;

            return function(expr) {
                if (Ext.isEmpty(expr)) {
                    return Ext.emptyFn;
                }
                if (Ext.isFunction(expr)) {
                    return expr;
                }
                if (this.getUseSimpleAccessors() !== true) {
                    var i = String(expr).search(re);
                    if (i >= 0) {
                        return Ext.functionFactory('obj', 'var value; try {value = obj' + (i > 0 ? '.' : '') + expr + '} catch(e) {}; return value;');
                    }
                }
                return function(obj) {
                    return obj[expr];
                };
            };
        }()
    });