I always get the SHAREPOINT\System account for every account in a workflow

Question

I want to get the group of the connected user

The problem is when I connect to sharepoint by any account, the current logged in account in my workflow got by Web.CurrentUser is always SHAREPOINT\System.

What I want is the real connected user to check a group of this user:

public static bool IsUserMemberOfGroup(string groupName)
{
    using(SPSite site = new SPSite(sitename)){
        using(SPWeb oweb = site.OpenWeb()){
            SPUser user = oweb.CurrentUser;
            if(user.Groups["groupename"].loginName == groupName){
                //do something
            }
        }
    }
}

Answer 1

The code within a workflow is executed by the system account (farm account). Thus, when you try to get the user that way, you will only get the system account. You need to retrieve the user from the properties of the workflow instance. See Get the current user interacting with a site workflow for info on how.