[c#] Select multiple columns using Entity Framework

Maybe an easy question, but can't find it easily so forgive me =) I try to select multiple columns. The statement I use is:

var dataset2 = from recordset in entities.processlists 
               where recordset.ProcessName == processname 
               select recordset.ServerName, recordset.ProcessID, recordset.Username;

Obviously, this doesn't even compile. What is the correct syntax? I also tried method based, and even tough this syntax seems correct, when accessing it throws an 'Unable to cast the type 'Anonymous type' to type 'AIM.PInfo'. LINQ to Entities only supports casting EDM primitive or enumeration types.' exception.

Any ideas?

var dataset = entities.processlists
             .Where(x => x.environmentID == environmentid && x.ProcessName == processname && x.RemoteIP == remoteip && x.CommandLine == commandlinepart)
             .Select(x => new { x.ServerName, x.ProcessID, x.Username })
             .Cast<PInfo>().ToList();

Why don't you create a new object right in the .Select:

.Select(x => new PInfo{ 
    ServerName = x.ServerName, 
    ProcessID = x.ProcessID, 
    UserName = x.Username }).ToList();

You either want to select an anonymous type:

var dataset2 = from recordset 
               in entities.processlists 
               where recordset.ProcessName == processname 
               select new 
               {
                recordset.ServerName, 
                recordset.ProcessID, 
                recordset.Username
               };

But you cannot cast that to another type, so I guess you want something like this:

var dataset2 = from recordset 
               in entities.processlists 
               where recordset.ProcessName == processname 

               // Select new concrete type
               select new PInfo
               {
                ServerName = recordset.ServerName, 
                ProcessID = recordset.ProcessID, 
                Username = recordset.Username
               };

You can select to an anonymous type, for example

var dataset2 = 
    (from recordset in entities.processlists 
    where recordset.ProcessName == processname 
    select new
    {
        serverName = recordset.ServerName,
        processId = recordset.ProcessID, 
        username = recordset.Username
    }).ToList();

Or you can create a new class that will represent your selection, for example

public class MyDataSet
{
    public string ServerName { get; set; }
    public string ProcessId { get; set; }
    public string Username { get; set; }
}

then you can for example do the following

 var dataset2 = 
    (from recordset in entities.processlists 
    where recordset.ProcessName == processname 
    select new MyDataSet
    {
        ServerName = recordset.ServerName,
        ProcessId = recordset.ProcessID, 
        Username = recordset.Username
    }).ToList();

Here is a code sample:

var dataset = entities.processlists
    .Where(x => x.environmentID == environmentid && x.ProcessName == processname && x.RemoteIP == remoteip && x.CommandLine == commandlinepart)
    .Select(x => new PInfo 
                 { 
                      ServerName = x.ServerName, 
                      ProcessID = x.ProcessID, 
                      UserName = x.Username 
                 }) AsEnumerable().
               Select(y => new PInfo
               {
                   ServerName = y.ServerName,
                   ProcessID = y.ProcessID,
                   UserName = y.UserName 
               }).ToList();

var test_obj = from d in repository.DbPricing
join d1 in repository.DbOfficeProducts on d.OfficeProductId equals d1.Id
join d2 in repository.DbOfficeProductDetails on d1.ProductDetailsId equals d2.Id
    select new
    {
    PricingId = d.Id,
    LetterColor = d2.LetterColor,
    LetterPaperWeight = d2.LetterPaperWeight
    };


http://www.cybertechquestions.com/select-across-multiple-tables-in-entity-framework-resulting-in-a-generic-iqueryable_222801.html

It's correct way to get data in specified type:

var dataset = entities.processlists
         .Where(x => x.environmentID == environmentid && x.ProcessName == processname && x.RemoteIP == remoteip && x.CommandLine == commandlinepart)
         .Select(x => new { x.ServerName, x.ProcessID, x.Username })
         .ToList() /// To get data from database
         .Select(x => new PInfo()
              { 
                   ServerName = x.ServerName, 
                   ProcessID = x.ProcessID, 
                   Username = x.Username 
              });

For more information see: The entity cannot be constructed in a LINQ to Entities query