Linq - 如何从匿名类型中区分多个字段

Question

userdetails class is defined:

class userdetails 
{      
 public string FromUserId;
 public string ToUserID;
 ... more properties
}  
var values = userdetails .Select(i => new { i.FromUserID, 
             i.ToUserID}).Distinct();

I want to get list of all the distinct userids from both the fields.

Answer 1

If I understand your question correctly, you want a single list containing unique values from FromUserId and ToUserId fields. In that case you want to union lists of each ID type.

var userDetails = new List<userdetails>();
// fill list with values.

var values = userDetails.Select(i => i.FromUserID).Union(userDetails.Select(i => i.ToUserID));