How to add a SharePoint group as Group Owner with Client Object Model?

Question

If you want to create a group and add group owner and default user you can use the following codes:

string siteUrl = "https://server/sites/sitename";
ClientContext clientContext = new ClientContext(siteUrl);
Web web = clientContext.Web;

GroupCreationInformation groupCreationInfo = new GroupCreationInformation();
groupCreationInfo.Title = "Custom Group";
groupCreationInfo.Description = "description ...";

User owner = web.EnsureUser(@"domain\username1");    
User member = web.EnsureUser(@"domain\username2");

Group group = web.SiteGroups.Add(groupCreationInfo);    
group.Owner = owner;             
group.Users.AddUser(member);     
group.Update(); 

clientContext.ExecuteQuery();

My question is: I know how to add a user as Group Owner but if I want to add a SharePoint group "Tech Support" as the group owner what the code should be?

Answer 1

Use GroupCollection.GetByName or GroupCollection.GetById method to retrieve an existing group from site and then set Group.Owner property to its value, for example:

using (var ctx = new ClientContext(webUri))
{
    ctx.Credentials = credentials;

    var groupCreationInfo = new GroupCreationInformation
    {
         Title = groupName,
         Description = groupDesc
    };

    var groupOwner = ctx.Web.SiteGroups.GetByName("Tech Support"); //get an existing group

    var group = ctx.Web.SiteGroups.Add(groupCreationInfo);
    group.Owner = groupOwner;
    group.Update();
    ctx.ExecuteQuery();     
}