如何转换类型&#39;System.Collections.Generic.IEnumerable <AnonymousType#1> &#39;到&#39;System.Collections.Generic.IEnumerable &lt;&gt;&#39;。

Question

I need to convert the following linq to a List directly,if I convert it to list I still get the error I explained on the subject,its said I need to convert it to list,but still the error is there,how can I convert it to list of string?without using additional conversion like foreach,...

List<string>  eventResult= (from c in DB.Events
                        where (c.m_turbine_id == turbineid.turbineID) && (c.m_time_stamp >= frmDate && c.m_time_stamp <= toDate)

                 select new EventLogPartialViewModel
                 {
                     Timestamp = c.m_time_stamp,
                     Description = c.m_event_log_description,
                     WindSpeed = c.m_wind_speed,
                     RPM = c.m_rpm,
                     Power = c.m_power
                 }).ToList().Select(x => new
                           {
                               Timestamp = x.Timestamp.ToString("dd/MM/yyyy H:mm:ss"),
                               Description = x.Description,
                               WindSpeed = x.WindSpeed,
                               RPM = x.RPM,
                               Power = x.Power
                           }).ToList().OrderByDescending(m => m.Timestamp);

the first part of the above linq,i get the data and convert to list because I need to change my time stamp format,any help will be appreciated .

Answer 1

As you need to create list of comma separated values with header,

//Add headers as first item
List<string>  eventResult = new List<string>(){"Timestamp,Description,WindSpeed,RPM,Power"};

//Add records
eventResult.AddRange(from c in DB.Events
                        where (c.m_turbine_id == turbineid.turbineID) && (c.m_time_stamp >= frmDate && c.m_time_stamp <= toDate)

                 select new EventLogPartialViewModel
                 {
                     Timestamp = c.m_time_stamp,
                     Description = c.m_event_log_description,
                     WindSpeed = c.m_wind_speed,
                     RPM = c.m_rpm,
                     Power = c.m_power
                 }).ToList().Select(x => 
                      x.Timestamp.ToString("dd/MM/yyyy H:mm:ss")) + "," +
                      x.Description + "," +
                      x.WindSpeed + "," +
                      x.RPM + "," +
                      x.Power

                 .ToList());

Answer 2

In the Linq query, you are selecting anonymous complex type so you can't assign it a List<string> . You should use var to keep reference of anonymous type.

var eventResult= (from c in DB.Events
                        where (c.m_turbine_id == turbineid.turbineID) && (c.m_time_stamp >= frmDate && c.m_time_stamp <= toDate)

                 select new EventLogPartialViewModel
                 {
                     Timestamp = c.m_time_stamp,
                     Description = c.m_event_log_description,
                     WindSpeed = c.m_wind_speed,
                     RPM = c.m_rpm,
                     Power = c.m_power
                 }).ToList().Select(x => new
                           {
                               Timestamp = x.Timestamp.ToString("dd/MM/yyyy H:mm:ss"),
                               Description = x.Description,
                               WindSpeed = x.WindSpeed,
                               RPM = x.RPM,
                               Power = x.Power
                           }).OrderByDescending(m => m.Timestamp).ToList();

Also, the ideal way is creating a class for complex type to handle reference instead of using anonymous type.