How to Programmatically Impersonate Users in SharePoint

There are times when developing custom web parts and other SharePoint solutions, you need to impersonate a user and view SharePoint from within their context. Impersonating a user in SharePoint requires a few things:

• the account that the web or console application users that has privileges to impersonate other users (typically this would be the system account)
• specific users’ user tokens

  Step 1: Log in as the system account, or get a handle to the system account in your code

string siteURL = "http://mysite/";
 
// we just need to get a handle to the site for us
// to get the system account user token
SPSite parentSite = new SPSite(siteURL);
 
SPUserToken systemToken = parentSite.SystemAccount.UserToken;
 
using (SPSite site = new SPSite(siteURL, systemToken))
{
    using (SPWeb web = site.OpenWeb())
    {
        // Add code to initiate impersonation
    }
}

  Step 2: Before you impersonate, get the user token of the user you are switching to. For example:

// Get the current user's user token
SPUserToken userToken = web.AllUsers[user].UserToken;
 
// Create an SPSite object in the context of the user
SPSite site = new SPSite(siteURL, userToken)
SPWeb web = site.OpenWeb();
 
// Add code to be executed in context of impersonation

  Complete code follows:

private static void ImpersonateUser()
{
    string siteURL = "http://mysite/";
    SPSite parentSite = new SPSite(siteURL);
    SPUserToken systemToken = parentSite.SystemAccount.UserToken;
    using (SPSite site = new SPSite(siteURL, systemToken))
    {
        using (SPWeb web = site.OpenWeb())
        {
            OpenUserContext(web, siteURL, "DOMAIN/JoeDoe");
        }
    }
}
 
private static void OpenUserContext(SPWeb web, string siteURL, string user)
{
    SPUserToken userToken = web.AllUsers[user].UserToken;
    SPSite impSite = new SPSite(siteURL, userToken);
    SPWeb impWeb = impSite.OpenWeb();
     
    // Do something as impersonated user
    Console.WriteLine("Currently logged in as: " + impWeb.CurrentUser.ToString() + "(" + impWeb.CurrentUser.Name + ")");
}