MSDN Magazine - July 2008 - (Page 67)

Figure 11 Building the Tree View TreeView1.Nodes.Clear(); appDataUri = string.Format(@"http://{0}.{1}{2}", conSSDSAuthName, conSSDSUri, "Categories"); query = @"from e in entities where e.Kind == ""Category"" select e"; UriBuilder newUri = new UriBuilder(appDataUri); newUri.Query = String.Format("q='{0}'", Uri.EscapeDataString(query)); string xmlResults = HTTPHelper.GetHTTPWebRequest(newUri.Uri.ToString(), new System.Net.NetworkCredential(conSSDSUsername, conSSDSPassword)); XmlDocument categoriesDoc = new XmlDocument(); categoriesDoc.LoadXml(xmlResults); XmlNodeList nodeList = categoriesDoc.SelectNodes("//Category"); int nodeIndex = 0; foreach (XmlNode node in nodeList) { if (node.ChildNodes.Count > 3) { int propCount = ((node.ChildNodes.Count - 1) / 2); TreeNode tn = new TreeNode(node.ChildNodes[2].InnerText, node.ChildNodes[0].InnerText); TreeView1.Nodes.Add(tn); for(int x=1;x<propCount;x++) { tn = new TreeNode(node.ChildNodes[(x*2)+2].InnerText, node.ChildNodes[(x*2)+1].InnerText); TreeView1.Nodes[nodeIndex].ChildNodes.Add(tn); } GetHTTPWebRequest is a static helper method to hide some of the HTTP details: WebRequest request = HttpWebRequest.Create(Uri.EscapeUriString(serviceUri)); request.Credentials = requestCredential; request.Method = "GET"; request.ContentType = XmlContentType; // Get the response and read it in to a string. using (HttpWebResponse response = (HttpWebResponse)request.GetResponse()) { } return ReadResponse(response); Now all that needs to be done is to create a new WebRequest object, set the Credentials that were passed to it, set the appropriate HTTP verb, set the ContentType to XML, and call the GetResponse method. I then call ReadResponse, which is another static helper method which uses a stream reader to read the HTTPResponse and return it to the caller. The code behind then takes the returned XML, loads it up into a XmlDocument, and loads the tree view with it. Class Deserialization } else { TreeNode tn = new TreeNode(node.ChildNodes[2].InnerText, node.ChildNodes[0].InnerText); TreeView1.Nodes.Add(tn); } } nodeIndex++; Up to this point, the code has simply been manually manipulating XML, but it’s easy to take an entity and deserialize it into a class. In this case, the application will be using a CityServed class. The base Entity class is pretty basic. The class contains properties for both the ID and Version, which are common to all entities. It also contains the necessary attributes so that the class is serializable. CityServed, shown in Figure 12, inherits from the base Entity class. A generic Query method returns a list of entities of type CityServed: foreach (CityServed i in HTTPHelper.Query ( appDataUri, query, new System.Net.NetworkCredential( conSSDSUsername, conSSDSPassword))) To start, look back at the main interface of the Web app shown in Figure 1. There is a tree view that represents the listing categories, a main content area, and a Datalist of all the cities that the application is currently configured to support. Looking into each one, I’ll show you how easy it is to develop an ASP.NET app against SSDS. If you look at the ASPX code for the tree view, you’ll see that it is quite simple: Groups The Query method, included in the code download for this article, is simply a generic static helper method that calls the same GetHTTPWebRequest method as we had used earlier. The Serialize and Deserialize methods are shown in Figure 13. The Query Figure 12 CityServed [XmlRoot(ElementName = "CityServed", Namespace = "")] public class CityServed : Entity { [XmlElement(ElementName = "AuthorityUri")] public object AuthorityUriField; [XmlElement(ElementName = "Name")] public object NameField; public override string ToString() { return Name; } [XmlIgnore] public string AuthorityUri { get { return (string)AuthorityUriField; } set { AuthorityUriField = value; } } [XmlIgnore] public string Name { get { return (string)NameField; } set { NameField = value; } } The magic happens in the code behind, as you can see in Figure 11. The first thing for you to be concerned with is the building of the URI, which is the pointer to the Categories container. Since this data is not city-specific, I have chosen to store it in the main contosoclassifieds authority, within the Categories container. Following that, I proceed to use a LINQ query to retrieve all entities with a Kind category, and then I use a UriBuilder object to put it all together and add the necessary HTTP escaping. Next, I go ahead and call the GetHTTPWebRequest method, passing in the escaped URI and a NetworkCredential object with the SSDS user name and password. GetHTTPWebRequest returns a string representation of an EntitySet with all Entities that satisfy the query predicates. msdnmagazine.com } July 2008 67 http://msdnmagazine.com

Table of Contents Feed for the Digital Edition of MSDN Magazine - July 2008

MSDN Magazine - July 2008 Contents Toolbox CLR Inside Out Flex Your Data Data Points Advanced Basics Office Space Cutting Edge Data Services ADO.NET Data and WPF Transactions WCF P2P Test Run Security Briefs Foundations .NET Matters {End Bracket}

MSDN Magazine - July 2008

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