Updating an Entity Using REST (C#)
[This document supports a preliminary release of a software product that may be changed substantially prior to final commercial release. This document is provided for informational purposes only.]
As described in Updating an Entity Using REST, the following C# sample the application illustrates a non-blob entity update. The application performs the following steps:
- Create an XML payload describing a sample book entity.
- Send a POST request to create the entity. In the request the application sets the
Content-Typerequest header toapplication/x-ssds+xmlindicating XML payload. - Send a GET request to retrieve the entity.
- Load the response string into an
XmlDocumentobject. - Add a new property
(<year>) to the book XML - Serialize the
XmlDocumentobject back to a string. - Send the updated string back in a PUT request.
Note
Credentials are required to access the service. To make a working sample, update following code and provide your existing authority id, container id and a unique id for the sample entity.
If you are using the Microsoft Visual Studio integrated development environment, create a console application and add the following code.
using System;
using System.Text;
using System.Net;
using System.Xml;
using System.IO;
using System.Xml.Linq;
namespace UpdateEntityUsingREST
{
class Program
{
// Provide your data here
private static string userName;
private static string password;
private const string authorityId = "<YourExistingAuthorityId>";
private const string containerId = "<YourExistingContainerId>";
private const string sampleEntityId = "<IdForSampleEntity>";
private const string HttpGetMethod = "GET";
private const string HttpPutMethod = "PUT";
private const string ssdsContentType = "application/x-ssds+xml";
static void Main(string[] args)
{
Console.Write("Username: ");
userName = Console.ReadLine();
Console.Write("Password: ");
password = ReadPassword();
string containerUri = String.Format("https://{0}.data.database.windows.net/v1/{1}", authorityId, containerId);
// Data going over to the server
string requestPayload = CreateBook(sampleEntityId, "My first used book using REST",
"Some summary", "1-57880-057-9",
"Author A", "Publisher B");
try
{
// Send request to create book entity
String bookUri = CreateEntity(containerUri, requestPayload);
if (bookUri == null)
{
Console.WriteLine("Book URI is null... problem creating sample entity");
return;
}
string data = GetEntity(bookUri);
// Load book XML in
XmlDocument bookXML = new XmlDocument();
bookXML.LoadXml(data);
// Update data by adding new flex property "Year"
XmlElement newElem = bookXML.CreateElement("year");
newElem.InnerXml = "2005";
newElem.SetAttribute("type", "http://www.w3.org/2001/XMLSchema-instance", "x:string");
bookXML.DocumentElement.AppendChild(newElem);
string updatedData = bookXML.OuterXml;
// Send updated entity back
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(bookUri);
request.Method = HttpPutMethod;
UTF8Encoding encoding = new UTF8Encoding();
request.ContentLength = encoding.GetByteCount(updatedData);
request.ContentType = ssdsContentType;
request.Credentials = new NetworkCredential(userName, password);
// Write the request data over the wire.
using (Stream reqStm = request.GetRequestStream())
{
reqStm.Write(encoding.GetBytes(updatedData), 0,
encoding.GetByteCount(updatedData));
}
// Get the response and read it in to a string.
using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
{
if (response.StatusCode == HttpStatusCode.OK)
{
Console.WriteLine("Entity update. Newer entity version: {0}", response.Headers["ETag"]);
}
else
{
Console.WriteLine("Unexpected status code returned: {0}", response.StatusCode);
}
}
}
catch (WebException ex)
{
using (HttpWebResponse response = ex.Response as HttpWebResponse)
{
if (response != null)
{
string errorMsg = ReadResponse(response);
Console.WriteLine(string.Format("Error:{0}", errorMsg));
Console.WriteLine("Unexpected status code returned: {0} ", response.StatusCode);
}
}
}
}
public static string CreateBook(string id, string title, string summary,
string isbn, string author, string publisher)
{
const string EntityTemplate =
@"<Book xmlns:s='https://schemas.microsoft.com/sitka/2008/03/'
xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'
xmlns:x='http://www.w3.org/2001/XMLSchema' >
<s:Id>{0}</s:Id>
<title xsi:type='x:string'>{1}</title>
<summary xsi:type='x:string'>{2}</summary>
<isbn xsi:type='x:string'>{3}</isbn>
<author xsi:type='x:string'>{4}</author>
<publisher xsi:type='x:string'>{5}</publisher>
</Book>";
return String.Format(EntityTemplate, id, title, summary, isbn, author, publisher);
}
private static string GetEntity(string entityUri)
{
string data = null;
if (string.IsNullOrEmpty(entityUri))
{
throw new ArgumentOutOfRangeException("entityUri");
}
try
{
// retrieve
WebRequest request = HttpWebRequest.Create(entityUri);
request.Method = HttpGetMethod;
//request.ContentLength = 0;
request.ContentType = ssdsContentType;
request.Credentials = new NetworkCredential(userName, password);
using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
{
data = ReadResponse(response);
if (response.StatusCode != HttpStatusCode.OK)
{
Console.WriteLine("Error: {0}", data);
Console.WriteLine("Unexpected status code returned: {0}", response.StatusCode);
}
}
}
catch (WebException ex)
{
using (HttpWebResponse response = ex.Response as HttpWebResponse)
{
if (response != null)
{
string errorMsg = ReadResponse(response);
Console.WriteLine("Error:{0}", errorMsg);
Console.WriteLine("Unexpected status code returned: {0}", response.StatusCode);
throw ex;
}
}
}
return data;
}
public static string CreateEntity(string containerUri, string requestPayload)
{
const string HttpPostMethod = "POST";
const string ssdsContentType = "application/x-ssds+xml";
string entityUri = null;
if (String.IsNullOrEmpty(containerUri))
{
throw new ArgumentOutOfRangeException(containerUri);
}
if (String.IsNullOrEmpty(requestPayload))
{
throw new ArgumentOutOfRangeException(requestPayload);
}
try
{
// Create the request to send.
WebRequest request = HttpWebRequest.Create(containerUri);
request.Credentials = new NetworkCredential(userName, password);
// POST=create; PUT=update; DELETE=delete; GET=retrieve
request.Method = HttpPostMethod;
UTF8Encoding encoding = new UTF8Encoding();
request.ContentLength = encoding.GetByteCount(requestPayload);
request.ContentType = ssdsContentType;
// Write the request data over the wire.
using (Stream reqStm = request.GetRequestStream())
{
reqStm.Write(encoding.GetBytes(requestPayload), 0,
encoding.GetByteCount(requestPayload));
}
// Get the response and read it in to a string.
using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
{
if (response.StatusCode == HttpStatusCode.Created)
{
Console.WriteLine("Entity created. System assigned version: {0}", response.Headers["ETag"]);
// Since current implementation returns response.Headers[HttpResponseHeader.Location]
// value null, construct entity URI
entityUri = string.Format(containerUri + "/" + sampleEntityId);
}
else
{
Console.WriteLine("Unexpected status code returned: {0}", response.StatusCode);
}
}
}
catch (WebException ex)
{
string errorMsg = ex.Message;
if (ex.Response != null)
{
using (HttpWebResponse response = ex.Response as HttpWebResponse)
{
errorMsg = ReadResponse(response);
Console.WriteLine(string.Format("Error:{0}", errorMsg));
Console.WriteLine("Unexpected status code returned: {0} ", response.StatusCode);
}
}
Console.WriteLine("Entity creation failed: {0}", errorMsg);
}
return entityUri;
}
public static string ReadResponse(HttpWebResponse response)
{
// Begin by validating our inbound parameters.
//
if (response == null)
{
throw new ArgumentNullException("response", "Value cannot be null");
}
// Then, open up a reader to the response and read the contents to a string
// and return that to the caller.
//
string responseBody = "";
using (Stream rspStm = response.GetResponseStream())
{
using (StreamReader reader = new StreamReader(rspStm))
{
responseBody = reader.ReadToEnd();
}
}
return responseBody;
}
private static string ReadPassword()
{
StringBuilder retval = new StringBuilder();
ConsoleKeyInfo keyInfo;
while ((keyInfo = Console.ReadKey(true)).Key != ConsoleKey.Enter)
{
Console.Write("*");
retval.Append(keyInfo.KeyChar);
}
Console.WriteLine();
return retval.ToString();
}
}
}
To verify the update, enter the entity URI in the browser.
https://<authority-id>.data.database.windows.net/v1/<container-id>/<entity-id>