lib/Ext/data/proxy/Sql.js
function (record) {
        var me = this,
            fields = record.getFields(),
            idProperty = record.getIdProperty(),
            uniqueIdStrategy = me.getUniqueIdStrategy(),
            data = {},
            name, value;

        fields.each(function (field) {
            if (field.getPersist()) {
                name = field.getName();
                if (name === idProperty && !uniqueIdStrategy) {
                    return;
                }
                value = record.get(name);
                if (field.getType().type == 'date') {
                    value = me.writeDate(field, value);
                }
                data[name] = value;
            }
        }, me);

        return data;
    }
function (record) {
        var me = this,
            fields = record.getFields(),
            idProperty = record.getIdProperty(),
            uniqueIdStrategy = me.getUniqueIdStrategy(),
            data = {},
            name, value;

        fields.each(function (field) {
            if (field.getPersist()) {
                name = field.getName();
                if (name === idProperty && !uniqueIdStrategy) {
                    return;
                }
                value = record.get(name);
                if (field.getType().type == 'date') {
                    value = me.writeDate(field, value);
                }
                data[name] = value;
            }
        }, me);

        return data;
    }
Formats the data for each record before sending it to the server. This
method should be overridden to format the data in a way that differs from the default.
@param {Object} record The record that we are writing to the server.
@return {Object} An object literal of name/value keys to be written to the server.
By default this method returns the data property on the record.