How to LIKE (Recommend) an Office 365 Document Programmatically by C# CSOM Patterns and Practice

In this article, let us see, how to LIKE a Document in SharePoint Office 365 Programmatically by C# CSOM.

 using Microsoft.SharePoint.Client;
  using System;
  using System.Collections.Generic;
  
  namespace Office365.Console
  {
      class Program
      {
          static void Main(string[] args)
          {
              LikeADocument();
          }
  
          public static void LikeADocument()
          {
              OfficeDevPnP.Core.AuthenticationManager authMgr = new OfficeDevPnP.Core.AuthenticationManager();
  
              //Site URL
              string siteUrl = "https://******.sharepoint.com/sites/communitysite";
              // UserName 
              string userName = "sathish@******.onmicrosoft.com";
              //Password
              string password = "******";
  
  
              using (var clientContext = authMgr.GetSharePointOnlineAuthenticatedContextTenant(siteUrl, userName, password))
              {
                  try
                  {
                      Site site = clientContext.Site;
                      Web web = clientContext.Web;
  
                      clientContext.Load(web);
                      clientContext.Load(web.Lists);
                      clientContext.ExecuteQuery();
                      //Get the Tasks List
                      List list = web.Lists.GetByTitle("MyDocumentsLibrary");
  
                      //Get the Child Item - The IDs were Hard coded for the demo purpose
                      ListItem listItem = list.GetItemById(20);
                      clientContext.Load(listItem);
  
                      clientContext.ExecuteQuery();
  
                      List<FieldUserValue> newLikedBy = new List<FieldUserValue>();
                      
                      FieldUserValue uservalue = new FieldUserValue();
                      var Likeduser = web.EnsureUser("sathish@******.onmicrosoft.com");
                      clientContext.Load(Likeduser);
                      clientContext.ExecuteQuery();
  
                      if (Likeduser != null)
                      {
                          FieldUserValue userValue = FieldUserValue.FromUser(Likeduser.Title);
                          userValue.LookupId = Likeduser.Id;
  
                          if (!string.IsNullOrEmpty(userValue.LookupValue))
                          {
                              newLikedBy.Add(userValue); // We can add a lot of Users in this Generic List in a single shot.
                              // I have added only one User for the demo purpose.  
                          }
                      }
  
  
                      if (newLikedBy.Count > 0)
                      {
                          listItem["LikesCount"] = newLikedBy.Count;
                          listItem["LikedBy"] = newLikedBy;
                      }
  
                      listItem.Update();
                      clientContext.ExecuteQuery();
                  }
                  catch (Exception ex)
                  {
                      System.Console.ForegroundColor = ConsoleColor.Red;
                      System.Console.WriteLine("Exception Occured : " + ex.Message);
                      System.IO.File.AppendAllText("C:\Temp\Exception.txt", ex.Message + " - " + siteUrl + Environment.NewLine);
                  }
  
  
              }
  
  
              System.Console.WriteLine("Completed....");
              System.Console.WriteLine("Press Any Key to Exit ....");
              System.Console.ReadLine();
          }
  
  
  
      }
  }

The Output will be something like

Happy Coding,

Sathish Nadarajan.