The source code

/*!
 * Ext JS Library 3.3.0
 * Copyright(c) 2006-2010 Ext JS, Inc.
 * licensing@extjs.com
 * http://www.extjs.com/license
 */
/**
 * @class Ext.data.XmlWriter
 * @extends Ext.data.DataWriter
 * DataWriter extension for writing an array or single {@link Ext.data.Record} object(s) in preparation for executing a remote CRUD action via XML.
 * XmlWriter uses an instance of {@link Ext.XTemplate} for maximum flexibility in defining your own custom XML schema if the default schema is not appropriate for your needs.
 * See the {@link #tpl} configuration-property.
 */
Ext.data.XmlWriter = function(params) {
    Ext.data.XmlWriter.superclass.constructor.apply(this, arguments);
    // compile the XTemplate for rendering XML documents.
    this.tpl = (typeof(this.tpl) === 'string') ? new Ext.XTemplate(this.tpl).compile() : this.tpl.compile();
};
Ext.extend(Ext.data.XmlWriter, Ext.data.DataWriter, {
    /**
     * @cfg {String} documentRoot [xrequest] (Optional) The name of the XML document root-node.  Note:
     * this parameter is required only when sending extra {@link Ext.data.Store#baseParams baseParams} to the server
     * during a write-request -- if no baseParams are set, the {@link Ext.data.XmlReader#record} meta-property can
     * suffice as the XML document root-node for write-actions involving just a single record.  For requests
     * involving multiple records and NO baseParams, the {@link Ext.data.XmlWriter#root} property can
     * act as the XML document root.
     */
    documentRoot: 'xrequest',
    /**
     * @cfg {Boolean} forceDocumentRoot [false] Set to true to force XML documents having a root-node as defined
     * by {@link #documentRoot}, even with no baseParams defined.
     */
    forceDocumentRoot: false,
    /**
     * @cfg {String} root [records] The name of the containing element which will contain the nodes of an write-action involving multiple records.  Each
     * xml-record written to the server will be wrapped in an element named after {@link Ext.data.XmlReader#record} property.
     * eg:
<?xml version="1.0" encoding="UTF-8"?>
<user><first>Barney</first></user>

     * However, when multiple records are written in a batch-operation, these records must be wrapped in a containing
     * Element.
     * eg:
<?xml version="1.0" encoding="UTF-8"?>
    <records>
        <first>Barney</first></user>
        <records><first>Barney</first></user>
    </records>

     * Defaults to records.  Do not confuse the nature of this property with that of {@link #documentRoot}
     */
    root: 'records',
    /**
     * @cfg {String} xmlVersion [1.0] The version written to header of xml documents.
<?xml version="1.0" encoding="ISO-8859-15"?>
     */
    xmlVersion : '1.0',
    /**
     * @cfg {String} xmlEncoding [ISO-8859-15] The encoding written to header of xml documents.
<?xml version="1.0" encoding="ISO-8859-15"?>
     */
    xmlEncoding: 'ISO-8859-15',
    /**
     * @cfg {String/Ext.XTemplate} tpl The XML template used to render {@link Ext.data.Api#actions write-actions} to your server.
     * One can easily provide his/her own custom {@link Ext.XTemplate#constructor template-definition} if the default does not suffice.
     * Defaults to:
<?xml version="{version}" encoding="{encoding}"?>
    <tpl if="documentRoot"><{documentRoot}>
    <tpl for="baseParams">
        <tpl for=".">
            <{name}>{value}</{name}>
        </tpl>
    </tpl>
    <tpl if="records.length > 1"><{root}>',
    <tpl for="records">
        <{parent.record}>
        <tpl for=".">
            <{name}>{value}</{name}>
        </tpl>
        </{parent.record}>
    </tpl>
    <tpl if="records.length > 1"></{root}></tpl>
    <tpl if="documentRoot"></{documentRoot}></tpl>

     * Templates will be called with the following API
     * 
     * {String} version [1.0] The xml version.
     * {String} encoding [ISO-8859-15] The xml encoding.
     * {String/false} documentRoot The XML document root-node name or false if not required.  See {@link #documentRoot} and {@link #forceDocumentRoot}.
     * {String} record The meta-data parameter defined on your {@link Ext.data.XmlReader#record} configuration represents the name of the xml-tag containing each record.
     * {String} root The meta-data parameter defined by {@link Ext.data.XmlWriter#root} configuration-parameter.  Represents the name of the xml root-tag when sending multiple records to the server.
     * {Array} records The records being sent to the server, ie: the subject of the write-action being performed.  The records parameter will be always be an array, even when only a single record is being acted upon.
     *     Each item within the records array will contain an array of field objects having the following properties:
     *     
     *         {String} name The field-name of the record as defined by your {@link Ext.data.Record#create Ext.data.Record definition}.  The "mapping" property will be used, otherwise it will match the "name" property.  Use this parameter to define the XML tag-name of the property.
     *         {Mixed} value The record value of the field enclosed within XML tags specified by name property above.
     *     
     * {Array} baseParams.  The baseParams as defined upon {@link Ext.data.Store#baseParams}.  Note that the baseParams have been converted into an array of [{name : "foo", value: "bar"}, ...] pairs in the same manner as the records parameter above.  See {@link #documentRoot} and {@link #forceDocumentRoot}.
     * 
     */
    // Encoding the ? here in case it's being included by some kind of page that will parse it (eg. PHP)
    tpl: '<\u003fxml version="{version}" encoding="{encoding}"\u003f><{documentRoot}><{name}>{value}<{root}><{parent.record}><{name}>{value}',


    /**
     * XmlWriter implementation of the final stage of a write action.
     * @param {Object} params Transport-proxy's (eg: {@link Ext.Ajax#request}) params-object to write-to.
     * @param {Object} baseParams as defined by {@link Ext.data.Store#baseParams}.  The baseParms must be encoded by the extending class, eg: {@link Ext.data.JsonWriter}, {@link Ext.data.XmlWriter}.
     * @param {Object/Object[]} data Data-object representing the compiled Store-recordset.
     */
    render : function(params, baseParams, data) {
        baseParams = this.toArray(baseParams);
        params.xmlData = this.tpl.applyTemplate({
            version: this.xmlVersion,
            encoding: this.xmlEncoding,
            documentRoot: (baseParams.length > 0 || this.forceDocumentRoot === true) ? this.documentRoot : false,
            record: this.meta.record,
            root: this.root,
            baseParams: baseParams,
            records: (Ext.isArray(data[0])) ? data : [data]
        });
    },

    /**
     * createRecord
     * @protected
     * @param {Ext.data.Record} rec
     * @return {Array} Array of name:value pairs for attributes of the {@link Ext.data.Record}.  See {@link Ext.data.DataWriter#toHash}.
     */
    createRecord : function(rec) {
        return this.toArray(this.toHash(rec));
    },

    /**
     * updateRecord
     * @protected
     * @param {Ext.data.Record} rec
     * @return {Array} Array of {name:value} pairs for attributes of the {@link Ext.data.Record}.  See {@link Ext.data.DataWriter#toHash}.
     */
    updateRecord : function(rec) {
        return this.toArray(this.toHash(rec));

    },
    /**
     * destroyRecord
     * @protected
     * @param {Ext.data.Record} rec
     * @return {Array} Array containing a attribute-object (name/value pair) representing the {@link Ext.data.DataReader#idProperty idProperty}.
     */
    destroyRecord : function(rec) {
        var data = {};
        data[this.meta.idProperty] = rec.id;
        return this.toArray(data);
    }
});