从HttpContext.User.Claims中提取值

Question

我正在尝试从中提取电子邮件地址，HttpContext.User.Claims并且希望寻求帮助，以找到一种更好的方式对此进行编码（也许使用LINQ？）

我现在的操作方式似乎很琐。

var userClaimsList = HttpContext.User.Claims.ToList();

// List is of varying length but email is always 3rd from the bottom.

int emailPosition = userClaimsList.Count()-3; 

string searchString = "preferred_username: "; 

// dirtyEmail = "preferred_username: xyz@emailcom"

string dirtyEmail = userClaimsList[emailPosition].ToString();

string cleanEmail = dirtyEmail.Replace(searchString, "").ToLower().Trim();

我尝试了另一篇文章中推荐的LINQ解决方案，但收到错误消息Operator == cannot be applied to operands of type 'Claim' and 'string'。