Save group to people picker field in a list

Question

I have a list in SharePoint 2010 that has peoplepicker that I need to save from one to many groups to it. I've figured out how to save users, but stumped on saving many groups to a peoplepicker.

Example:

User selects one (or many) checkboxes. The value of each checkbox has a group name that is a group in my SharePoint site. I need to take these groups and save them to a people picker (inside one of my lists) that is configured to allow multiple entries.

Can someone provide and example or point me to a URL that will explain this?

Below is what I do for users. Is this close for groups? If so, can someone show me what to change to make this work for groups?

...

for (int i = 0; i < userarray.Length; i++)
{
assist = ConvertLoginName(web, userarray[i]);

if (assist != null)
    parsedAssists += assist.User.ID.ToString(CultureInfo.InvariantCulture) + ";#" + assist.User.LoginName.ToString(CultureInfo.InvariantCulture) + ";#";
}


Hashtable ht = new Hashtable();
ht.Add("Assist", parsedAssists);

...

SPFile file = list.RootFolder.Files.Add(fileUpload.FileName, fileUpload.PostedFile.InputStream, ht, false);

private SPFieldUserValue ConvertLoginName(SPWeb web, string userId)
{
    SPUser requireduser = web.EnsureUser(userId);
    SPFieldUserValue uservalue = new SPFieldUserValue(web, requireduser.ID, requireduser.LoginName);
    return uservalue;
}

Answer 1

By people picker, do you mean a Person or Group field (aka SPFieldUser?) These can be set to accept people, or, people and groups. Perhaps yours is only accepting people?

You can set this when creating the field in the UI and can probably do so after as well, or, use the SPFieldUser.SelectionMode property.