Create list item in sharepoint list using REST API using C#

Question

I have a requirement to create list item in a sharepoint online list using the REST API and c#. How to achieve this. Most of the article show using REST API in jquery and Javascript but I have a requirement to do this using c#. Please suggest if anyone have one with this problem.

Unfortunately, I am not getting any code sample for that.

Any kind of help will be appreciated. Thanks

Answer 1

Check out this MSDN article which might help you out. Here's Microsoft's example code for adding a single item to a list (title field only):

//Execute a REST request to get the form digest. All POST requests that change the state of resources on the host
//Web require the form digest in the request header.
HttpWebRequest contextinfoRequest =
    (HttpWebRequest)HttpWebRequest.Create(sharepointUrl.ToString() + "/_api/contextinfo");
contextinfoRequest.Method = "POST";
contextinfoRequest.ContentType = "text/xml;charset=utf-8";
contextinfoRequest.ContentLength = 0;
contextinfoRequest.Headers.Add("Authorization", "Bearer " + accessToken);

HttpWebResponse contextinfoResponse = (HttpWebResponse)contextinfoRequest.GetResponse();
StreamReader contextinfoReader = new StreamReader(contextinfoResponse.GetResponseStream(), System.Text.Encoding.UTF8);
var formDigestXML = new XmlDocument();
formDigestXML.LoadXml(contextinfoReader.ReadToEnd());
var formDigestNode = formDigestXML.SelectSingleNode("//d:FormDigestValue", xmlnspm);
string formDigest = formDigestNode.InnerXml;

//Execute a REST request to get the list name and the entity type name for the list.
HttpWebRequest listRequest =
    (HttpWebRequest)HttpWebRequest.Create(sharepointUrl.ToString() + "/_api/Web/lists(guid'" + listId + "')");
listRequest.Method = "GET";
listRequest.Accept = "application/atom+xml";
listRequest.ContentType = "application/atom+xml;type=entry";
listRequest.Headers.Add("Authorization", "Bearer " + accessToken);
HttpWebResponse listResponse = (HttpWebResponse)listRequest.GetResponse();
StreamReader listReader = new StreamReader(listResponse.GetResponseStream());
var listXml = new XmlDocument();
listXml.LoadXml(listReader.ReadToEnd());

//The entity type name is the required type when you construct a request to add a list item.
var entityTypeNode = listXml.SelectSingleNode("//atom:entry/atom:content/m:properties/d:ListItemEntityTypeFullName", xmlnspm);
var listNameNode = listXml.SelectSingleNode("//atom:entry/atom:content/m:properties/d:Title", xmlnspm);
string entityTypeName = entityTypeNode.InnerXml;
string listName = listNameNode.InnerXml;

//Execute a REST request to add an item to the list.
string itemPostBody = "{'__metadata':{'type':'" + entityTypeName + "'}, 'Title':'" + newItemName + "'}}";
Byte[] itemPostData = System.Text.Encoding.ASCII.GetBytes(itemPostBody);

HttpWebRequest itemRequest =
    (HttpWebRequest)HttpWebRequest.Create(sharepointUrl.ToString() + "/_api/Web/lists(guid'" + listId + "')/Items");
itemRequest.Method = "POST";
itemRequest.ContentLength = itemPostBody.Length;
itemRequest.ContentType = "application/json;odata=verbose";
itemRequest.Accept = "application/json;odata=verbose";
itemRequest.Headers.Add("Authorization", "Bearer " + accessToken);
itemRequest.Headers.Add("X-RequestDigest", formDigest);
Stream itemRequestStream = itemRequest.GetRequestStream();

itemRequestStream.Write(itemPostData, 0, itemPostData.Length);
itemRequestStream.Close();

HttpWebResponse itemResponse = (HttpWebResponse)itemRequest.GetResponse();
RetrieveListItems(accessToken, listId);

Instead of using an "access token" variable like accessToken, you can likely use SharePoint credentials instead, like in this example.

Answer 2

At least the following components could be utilized for that purpose:

• HttpWebRequest
• WebClient
• HttpClient

You might find this post helpful that demonstrates how to consume SharePoint REST API in .NET, in particular it demonstrates how to:

• perform authentication in SharePoint Online using HttpClient
• perform basic CRUD operations using HttpClient

See SPHttpClient class implementation that derives from HttpClient class for a details.

The following example demonstrates how to create a List Item:

using (var client = new SPHttpClient(webUri, userName, password))
{
    var itemPayload = new { __metadata = new { type = "SP.Data.TasksListItem" }, Title = "Approval Task" };
    var endpointUrl = string.Format("{0}/_api/web/lists/getbytitle('{1}')/items",webUri,listTitle);
    var item = client.ExecuteJson(endpointUrl, HttpMethod.Post, null, itemPayload);
    Console.WriteLine("Task '{0}' has been created successfully",item["Title"]);
}

Answer 3

If you know how to do it using REST/Js/jQuery, one of the possible way could be create the request with the help of Fiddler and pass that over to SP using WebRequest using C# application.