Code Snippet
  1. using System;
  2. using System.Collections.Generic;
  3. using System.Linq;
  4. using System.Net;
  5. using System.Security;
  6. using System.Text;
  7. using System.Threading.Tasks;
  8. using Microsoft.SharePoint.Client;
  10. namespace CSOMOffice365
  11. {
  12. class Program
  13. {
  14. static void Main(string[] args)
  15. {
  16. string userName = "[email protected]";
  18. Console.WriteLine("Enter your password.");
  19. SecureString password = GetPassword();
  21. // ClienContext - Get the context for the SharePoint Online Site
  22. // SharePoint site URL - https://c986.sharepoint.com
  24. using (var clientContext = new ClientContext("https://c986.sharepoint.com"))
  25. {
  27. // SharePoint Online Credentials
  28. clientContext.Credentials = new SharePointOnlineCredentials(userName, password);
  30. // Get the SharePoint web
  31. Web web = clientContext.Web;
  33. // Get the list by Title
  34. List list = web.Lists.GetByTitle("Custom");
  36. // Get a specific field by Title (TestCol - Single line of text)
  37. Field field = list.Fields.GetByTitle("TestCol");
  39. // Update the field type to multi line of text
  40. field.TypeAsString = "Note";
  41. field.Update();
  42. clientContext.Load(field);
  44. // Execute the query to the server
  45. clientContext.ExecuteQuery();
  47. // Display the field name and type
  48. Console.WriteLine(field.Title + " -- Field Type updated to : " + field.TypeAsString);
  49. Console.ReadLine();
  51. }
  53. }
  55. private static SecureString GetPassword()
  56. {
  57. ConsoleKeyInfo info;
  59. //Get the user's password as a SecureString
  60. SecureString securePassword = new SecureString();
  61. do
  62. {
  63. info = Console.ReadKey(true);
  64. if (info.Key != ConsoleKey.Enter)
  65. {
  66. securePassword.AppendChar(info.KeyChar);
  67. }
  68. }
  69. while (info.Key != ConsoleKey.Enter);
  70. return securePassword;
  71. }
  72. }
  73. }
Output