從linq查詢結果填充列表

Question

我有以下代碼，我要返回與userId關聯的結果，然后我想遍歷結果並構建一個集合，然后將其返回給UI。

 public List<UserEmails> LoadUsersInbox(Int64 userId, int status)
    {
        List<UserEmails> userEmails = null;

        using (var sqlCon = new SqlConnection(Context.ReturnDatabaseConnection()))
        {
            var emails = sqlCon.Query<UserEmailEntity>(@"SELECT e.EmailId, e.ItemId, u.Username as FromUserName, e.EmailReceived
                                                   FROM User_Emails e
                                                   INNER JOIN User_Profile u on e.FromUserId = u.UserId
                                                   WHERE ToUserId = @userId and EmailStatus = @Status",
                                                   new { ToUserId = userId, Status = status }).OrderBy(d => d.EmailReceived);

            foreach (var item in emails)
            {
                // loop through and build and List of UserEmails
            }
        }

        return userEmails;
    }

但是我無法弄清楚它的語法，請有人幫我。

Answer 1

您可以轉換列表，而無需進入foreach循環。 您可以使用Select語句執行此操作。 我無法驗證這一點（因此未經測試的代碼），但是如果您這樣做，它應該可以工作：

public List<Int64> LoadUsersInbox(Int64 userId, int status)
{
    using (var sqlCon = new SqlConnection(Context.ReturnDatabaseConnection()))
    {
       return sqlCon.Query<UserEmailEntity>
            (@"SELECT e.EmailId, e.ItemId, u.Username as FromUserName, e.EmailReceived
               FROM User_Emails e
               INNER JOIN User_Profile u on e.FromUserId = u.UserId
               WHERE ToUserId = @userId and EmailStatus = @Status",
               new { ToUserId = userId, Status = status })
            .OrderBy(d => d.EmailReceived)
            .Select(usrEmlEnt => usrEmlEnt.EmailId);
    }
    return new List<Int64>();
}