Update List Items using REST API - Keep Getting 400 Bad Request

Question

I am using code from the following answer:
http://social.msdn.microsoft.com/Forums/sharepoint/en-US/40833576-5853-4ca4-95cf-b5b1d69f465f/sharepoint-rest-and-c-sample-to-update-list-item?forum=sharepointdevelopment
I am having a tough time figuring out the issue though.  I have been able to retrieve list items, but now I want to update those items.  This is the following code just to get the digest information with passing in credentials:
public static string GetFormDigest(System.Net.NetworkCredential cred)
string formDigest = null;
string resourceUrl = "https://SITEURL/_api/contextinfo";
HttpWebRequest wreq = HttpWebRequest.Create(resourceUrl) as HttpWebRequest;
wreq.Credentials = cred;
wreq.Method = "POST";
wreq.Accept = "application/json;odata=verbose";
wreq.ContentLength = 0;
wreq.ContentType = "application/json";
string result;
WebResponse wresp = wreq.GetResponse();
using (StreamReader sr = new StreamReader(wresp.GetResponseStream()))
result = sr.ReadToEnd();
var jss = new JavaScriptSerializer();
var val = jss.Deserialize<Dictionary<string, object>>(result);
var d = val["d"] as Dictionary<string, object>;
var wi = d["GetContextWebInformation"] as Dictionary<string, object>;
formDigest = wi["FormDigestValue"].ToString();
Console.WriteLine(formDigest);
return formDigest;
Then the following code is used:
string result = string.Empty;
Uri uri = new Uri(sharepointUrl.ToString() + "/_api/Web/lists/getByTitle('DemoList')/items(1)");
HttpWebRequest wreq = (HttpWebRequest)WebRequest.Create(uri);
wreq.Credentials = cred;
wreq.Method = "POST";
wreq.Accept = "application/json; odata=verbose";
wreq.ContentType = "application/json; odata=verbose";
wreq.Headers.Add( "X-HTTP-Method","MERGE");
wreq.Headers.Add( "IF-MATCH", "*");
wreq.Headers.Add("X-RequestDigest", GetFormDigest(cred));
string stringData = "{'__metadata': { 'type': 'SP.Data.DemoListListItem' }, 'Title': 'updated!'}";
wreq.ContentLength = stringData.Length;
StreamWriter writer = new StreamWriter(wreq.GetRequestStream());
writer.Write(stringData);
writer.Flush();
try {
WebResponse wresp2 = wreq.GetResponse();
using (StreamReader sr = new StreamReader(wresp2.GetResponseStream()))
result = sr.ReadToEnd();
catch (Exception e) { Console.WriteLine("An error occurred: '{0}'", e); }
It errors out when it tries to send the command to Sharepoint.  I am NOT using a sharepoint hosted app.  I just wanted to directly contact sharepoint and update items.  Any help or suggestions would be greatly appreciated!
Thanks,
Priyank
 

Answer 1

I just found some other code that seemed to work on editing a title and edited it kind of guessing it would work and it did!
This is the code that ended working using the same digest code from above:
Console.WriteLine("\n Newer Fancier Code \n");
Uri uri = new Uri("https://SHAREPOINTURL/_api/web/lists/GetByTitle('Demo')/items(1)");
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
request.ContentType = "application/json;odata=verbose";
request.Headers["X-RequestDigest"] = GetFormDigest(cred);
request.Headers["X-HTTP-Method"] = "MERGE";
request.Headers["IF-MATCH"] = "*";
request.Credentials = cred;
request.Accept = "application/json;odata=verbose";
request.Method = "POST";
string stringData = "{ '__metadata': { 'type': 'SP.ListItem' }, 'Location': 'updatedinfo' }";
request.ContentLength = stringData.Length;
StreamWriter writer = new StreamWriter(request.GetRequestStream());
writer.Write(stringData);
writer.Flush();
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
StreamReader reader = new StreamReader(response.GetResponseStream());
Just fyi if anyone was wondering.  Next, I'm going to be trying to update multiple fields, possibly multiple items if possible if anyone knows how to do that.