extjs: write an xml without root using xmlwriter - extjs

Question

when sending a response to a server using xmlwriter, the root tag will always be added to the request:
If I want to post an item:
<book>
<id></id>
<title></title>
<publisher></publisher>
</book>
the actual generated xml is:
<xmlData>
<book>
<id></id>
<title></title>
<publisher></publisher>
</book>
</xmlData>
I can make sure that only one record will be posted: one book for each request
how can I remove the xmlData element? that is to say, make book tag to be the root element
the extjs document says:
Ext.data.writer.Xml
documentRoot : String
The name of the root element of the document. Defaults to 'xmlData'. If there is more than 1 record and the root is not specified, the default document root will still be used to ensure a valid XML document is created.
My understanding is that if there is only one record, the default document root will not be used. Am I right? But acturaly, the root element 'xmlData' is still added even if there is only one record.
Thanks

Answer 1

The Ext.data.writer.Xml class has two configuration properties related to the root element: documentRoot and defaultDocumentRoot. As you noted, the documentation says:
If there is more than 1 record and the root is not specified, the default document root will still be used to ensure a valid XML document is created.
In other words, if documentRoot is null, but more than one record is written, the value of defaultDocumentRoot will be used as the root element. In your case, there is only one record, but documentRoot is not null, as its default value is "xmlData".
To omit the root element for single records, then, you need to explicitly set documentRoot to null:
new Ext.data.writer.Xml({ documentRoot: null });