get SPUser from Login Name string

1. Issue:Can't get object SPUser with code behind people picker inInFopath anyway check .
currentWeb.EnsureUser(userName);
currentWeb.AllUsers[userName];
Whole 2 method are Exception .


3. Solution:
1. Add reference to dll microsoft.office.workflow.tasks (search ở C )
2. using function under to getobject SPUser from data input is login name (ex: fsdn\vinhtv; vinhtv-g5\admin..)

///

/// Gets the user.
///

/// The web.
/// Name of the user.
///
public SPUser GetUser(SPWeb web, string userName)
{
SPUser newUser = null;

try
{
SPSecurity.RunWithElevatedPrivileges(delegate
{
using (SPSite site = new SPSite(web.Site.ID, web.Site.SystemAccount.UserToken))
{
using (SPWeb currentWeb = site.OpenWeb())
{
Contact contact = Contact.FromName(userName, currentWeb);

// if wthe user has already accessed teh site then id will be >=0
if (contact.PrincipalID < 0)
{
currentWeb.AllowUnsafeUpdates = true;

SPPrincipal p = contact.GetPrincipal(currentWeb);
}

newUser = currentWeb.SiteUsers[contact.LoginName];
currentWeb.AllowUnsafeUpdates = false;
}
}
});
}
catch (Exception ex)
{
throw ex;
}

return newUser;
}


Rource:VinhTv