How to get file owner of List in SharePoint 2016 and 2019 via CSOM C#.

Question

Hi, I need to fetch file owner of list. Below is my code.

clientContext.Load(list, l => l.Id, l => l.Title, l => l.BaseType, l => l.BaseTemplate, l => l.LastItemModifiedDate, l => l.Created,
l => l.DefaultViewUrl, l => l.Author.UserPrincipalName, l => l.Author.Title, l => l.ParentWebUrl, l => l.ParentWeb);
clientContext.ExecuteQueryWithIncrementalRetry();

Above code giving error stating "Field or property "Author" does not exist."
Able to fetch author property when targeting SP Online via CSOM. Also able to fetch when targeting SP OnPrem via SSOM.
But when doing it via CSOM - SP 2019 OnPrem, it is throwing error.

Answer 1

Hi @ASR ,
Per my test, We can get file author by CSOM. Please refer to following code

List targetList = clientcontext.Web.Lists.GetByTitle("Documents");  
ListItem oItem = targetList.GetItemById(2);  
CamlQuery oQuery = new CamlQuery();  
oQuery.ViewXml = @"<View><Query><Where>  
<Eq>  
<FieldRef Name='LinkFilename' />  
<Value Type='Text'>Document.docx</Value>  
</Eq>  
</Where></Query></View>";  
   
ListItemCollection oItems = targetList.GetItems(oQuery);  
clientcontext.Load(oItems);  
clientcontext.ExecuteQuery();  
   
oItem = oItems.FirstOrDefault();   
File targetFile = oItem.File;   
clientcontext.Load(targetFile);   
User oUser = targetFile.Author;   
clientcontext.Load(oUser);  
clientcontext.ExecuteQuery();  
   
Console.WriteLine("Author: " + oUser.LoginName);  

If we need list owner. We need to use SPList.Author property returns the SPUser field.

        using(SPSite site = newSPSite(strURL))    
        {    
            using(SPWeb web = site.OpenWeb())    
            {    
                SPList list = web.Lists.TryGetList(listName);    
                if (list != null) {    
                    SPUser listAuthor = list.Author;    
                    string authorName = listAuthor.Name;    
                    Console.WriteLine("List Author Name: {0}", authorName);    
                    retry = false;    
                } else    
                {    
                    Console.WriteLine("List with the name \"{0}\" not exists Please try some other name.", listName);    
                    retry = true;    
                }    
            }    
        }    

---------update---------

We can get author.Title but it seems there is no UserPrincipalName property in SharePoint 2019. Here is the sample for reference

     Web web = clientContext.Web;  
     List list = web.Lists.GetByTitle("TestList");  
     clientContext.Load(list, l => l.SchemaXml);  
     clientContext.ExecuteQuery();  
     string schemaxml = list.SchemaXml;  
     XmlDocument xmlDoc = new XmlDocument();  
     xmlDoc.LoadXml(schemaxml);  
     XmlNode listElement = xmlDoc.GetElementsByTagName("List")[0];  
     string authorid = listElement.Attributes["Author"].Value;  
     User author = web.GetUserById(Convert.ToInt32(authorid));  
     clientContext.Load(author);  
     clientContext.ExecuteQuery();  
     Console.WriteLine(author.Title);  
     Console.ReadLine();  

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