Topic:
Using
XPath to navigate through elements and attributes in an XML document
returned by a SharePoint Web Service.
This article proposes some
examples which will show to developers how to use XPath in spite of namespaces
present in the XML returned by Web services of SharePoint
1 - Business benefits (the "why" part of the post)
SharePoint
provides Web Services that can be consumed in order for example to get data
from a SharePoint Site, and display them within another web site or a
desktop application.
It is a part of what is commonly called "SOA" in
companies.
On the other hand, this principle can be applied to retrieve data
from SharePoint Internet facing web site so as they can be a part of a mashup in
a web site.
2- Development benefits
XPath allows developers to quickly navigate through elements and attributes in an XML document. It is very useful when there is no namespaces in the parsed XML, but it becomes more difficult when namespaces are used in the XML, especially if there is several namespaces and that they are present at different locations within the XML code.
2- Common examples
To
give common examples, we are going to use the Lists Web Service and two of its
methods.
This is a short Microsoft documentation excerpt and a link to
it:
Lists Web
Service
The Lists Web service provides methods for working with
SharePoint lists, content types, list items, and files.
To access this Web
service set a Web reference to
http://<site>/_vti_bin/Lists.asmx
- The GetListCollection Method returns the names and GUIDs for all lists in a specific web site, and the complete SOAP XML returned by the web service looks like this one:
Request result for SharePoint Web Service /_vti_bin/Lists.asmx GetList
<?xml
version='1.0' encoding='utf-8'?>
<soap:Envelope
xmlns:soap='http://schemas.xmlsoap.org/soap/envelope/'
xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'
xmlns:xsd='http://www.w3.org/2001/XMLSchema'>
<soap:Body>
<GetListCollectionResponse
xmlns='http://schemas.microsoft.com/sharepoint/soap/'>
<GetListCollectionResult>
<Lists>
<List
DocTemplateUrl='' DefaultViewUrl='/product/Lists/Demos/AllItems.aspx' MobileDefaultViewUrl='' ID='{91465226-671A-42EC-98ED-52C8C13403A1}' Title='D…
<List
DocTemplateUrl='/product/Documents/Forms/template.doc' DefaultViewUrl='/product/Documents/Forms/AllItems.aspx' MobileDefaultViewUrl='' ID='{3A9CB2…
<List
DocTemplateUrl='' DefaultViewUrl='/product/PublishingImages/Forms/AllItems.aspx' MobileDefaultViewUrl='' ID='{CB49539A-F215-41D3-8675-8CB6A0FAE9E2…
<List
DocTemplateUrl='' DefaultViewUrl='/product/_catalogs/masterpage/Forms/AllItems.aspx' MobileDefaultViewUrl='' ID='{E5E53853-B2A1-414F-AD18-62B6B274…
<List
DocTemplateUrl='' DefaultViewUrl='/product/Lists/News and
Reviews/AllItems.aspx' MobileDefaultViewUrl='' ID='{45A63226-979A-402A-A029-6115AF0BE184…
<List
DocTemplateUrl='' DefaultViewUrl='/product/Pages/Forms/AllItems.aspx' MobileDefaultViewUrl='' ID='{B61087A0-9E16-451D-8132-1038BFFB63F5}' Title='P…
<List
DocTemplateUrl='' DefaultViewUrl='/product/Lists/Web
Casts/AllItems.aspx' MobileDefaultViewUrl='' ID='{70F8653B-D81E-4AEE-8336-5A55789EB717}' Titl…
<List
DocTemplateUrl='' DefaultViewUrl='/product/WorkflowTasks/AllItems.aspx' MobileDefaultViewUrl='' ID='{75C8921E-9214-4212-998C-7AF611020D8D}' Title=…
</Lists>
</GetListCollectionResult>
</GetListCollectionResponse>
</soap:Body>
</soap:Envelope>
Now
this is the first example that shows how to manage the namespaces concern with
XPath. We will retrieve all the nodes corresponding to the SharePoint lists:
// Create a new XmlDocument
XmlDocument doc = new XmlDocument();
// Load data
doc.LoadXml(XmlSring);
// define namespaces
XmlNamespaceManager ns = new XmlNamespaceManager(doc.NameTable);
ns.AddNamespace("soap", "http://schemas.xmlsoap.org/soap/envelope/");
ns.AddNamespace("namespace", "http://schemas.microsoft.com/sharepoint/soap/");
// retrieve the lists nodes
XmlNodeList Lists =
doc.SelectNodes("//soap:Envelope/soap:Body/namespace:GetListCollectionResponse/namespace:GetListCollectionResult/namespace:Lists",
ns);
-
The GetListItems Method returns information about items in the list based on the
specified query and the complete SOAP XML returned by the web service looks like
this one:
<?xml
version="1.0" encoding="utf-8"?>
<soap:Envelope
xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLS...
<soap:Body>
<GetListItemsResponse
xmlns="http://schemas.microsoft.com/sharepoint/soap/">
<GetListItemsResult>
<listitems
xmlns:s='uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882' xmlns:dt='uuid:C2F41010-65B3-11d1-A29F-00AA00C14882' xmlns:rs='urn:schemas-microsof...
<rs:data
ItemCount="6">
<z:row
ows_SilverlightBackgroundURL='http://sharepoint.microsoft.com/PublishingImages/home-2010_beta_banner.jpg' ows_HyperlinkURL='http://
...
<z:row
ows_LinkTitle='Enterprise Social Computing with SharePoint' ows_SilverlightBackgroundURL='http://sharepoint.microsoft.com/Publishin...
<z:row
ows_LinkTitle='Save Money with SharePoint'
ows_SilverlightBackgroundURL='http://sharepoint.microsoft.com/PublishingImages/SP_News_S...
<z:row
ows_LinkTitle='Introducing Microsoft Office 2010 Beta' ows_SilverlightBackgroundURL='http://sharepoint.microsoft.com/PublishingImag...
<z:row
ows_LinkTitle='Microsoft Office for the Mac SP2' ows_SilverlightBackgroundURL='http://sharepoint.microsoft.com/PublishingImages/SP_...
<z:row
ows_SilverlightBackgroundURL='http://msn.com'
ows_HyperlinkURL='http://msn.com,
http://msn.com' ows_HyperlinkXoffset='-50' ows_Hype..
</rs:data>
</listitems>
</GetListItemsResult>
</GetListItemsResponse>
</soap:Body>
</soap:Envelope>
This
is the second example that shows how to manage the namespaces concern with
XPath. We will retrieve all the nodes corresponding to the items of a SharePoint
list:
// Create a new XmlDocument
XmlDocument doc = new XmlDocument();
// Load data
doc.LoadXml(XmlString);
// define namespaces
XmlNamespaceManager ns = new XmlNamespaceManager(doc.NameTable);
ns.AddNamespace("soap", "http://schemas.xmlsoap.org/soap/envelope/");
ns.AddNamespace("namespace", "http://schemas.microsoft.com/sharepoint/soap/");
ns.AddNamespace("rs", "urn:schemas-microsoft-com:rowset");
// retrieve the list items nodes
XmlNodeList data =
doc.SelectNodes("//soap:Envelope/soap:Body/namespace:GetListItemsResponse/namespace:GetListItemsResult/namespace:listitems/rs:data",
ns);
