The entity or complex type cannot be constructed in a LINQ to Entities query [duplicate] - entity-framework

Question

This question already has answers here:
The entity cannot be constructed in a LINQ to Entities query
(14 answers)
Closed 10 years ago.
I have two functions that look exactly the same except they create lists of two different objects. The two different objects look very much alike, but when I try to run one of the functions on one of the objects, I get the error message, "The entity or complex type cannot be constructed in a LINQ to Entities query.". Can someone explain to me what is happening in very simple terms? Also, can you tell me how to change my code so that it works? Thanks, Allan.
Function 1 (works):
public static List<ChartApp> ListChartApplications()
{
using (var db = new LatencyDBContext())
{
var appNames = db.LoginApplications.Select(item => new ChartApp()
{
LoginApplicationID = item.LoginApplicationID,
LoginAppName = item.LoginAppName,
}).OrderBy(item => item.LoginAppName);
return appNames.ToList();
}
}
Function 2 (throws error on "return appNames.ToList();"):
public static List<LoginApplication> ListApplications()
{
using (var db = new LatencyDBContext())
{
var appNames = db.LoginApplications.Select(item => new LoginApplication()
{
LoginApplicationID = item.LoginApplicationID,
LoginAppName = item.LoginAppName,
}).OrderBy(item => item.LoginAppName);
return appNames.ToList();
}
}
Classes:
public class ChartApp
{
public ChartApp()
{
this.LoginHistories = new List<ChartHist>();
}
public int? LoginApplicationID { get; set; }
public string LoginAppName { get; set; }
public virtual ICollection<ChartHist> LoginHistories { get; set; }
public int Step { get; set; }
}
public class LoginApplication
{
public LoginApplication()
{
this.LoginHistories = new List<LoginHistory>();
}
public int LoginApplicationID { get; set; }
public string LoginAppName { get; set; }
public virtual ICollection<LoginHistory> LoginHistories { get; set; }
}
Edit: Could the difference possibly be that one of the objects are mapped to the database?
public class LoginApplicationMap : EntityTypeConfiguration<LoginApplication>
{
public LoginApplicationMap()
{
// Primary Key
this.HasKey(t => t.LoginApplicationID);
// Properties
this.Property(t => t.LoginAppName)
.HasMaxLength(500);
// Table & Column Mappings
this.ToTable("LoginApplication");
this.Property(t => t.LoginApplicationID).HasColumnName("LoginApplicationID");
this.Property(t => t.LoginAppName).HasColumnName("LoginAppName");
}
}

Answer 1

My solution in this case was to just delete the non-working function and use the working one in all places. For, similar functions that are mapped, I use the following function to return values.
public static List<LoginEnvironment> ListEnvironments(bool allSelection)
{
using (var db = new LatencyDBContext())
{
//GET ALL THE ENVIRONMENT NAMES
var envNames = from e in db.LoginEnvironments
orderby e.LoginEnvName
select e;
//PUT ALL THE ENVIRONMENTS INTO A LOCAL LIST
var listEnv = new List<LoginEnvironment>();
if (allSelection)
{
var defaultAll = new LoginEnvironment();
defaultAll.LoginEnvironmentID = 0;
defaultAll.LoginEnvName = "All";
listEnv.Add(defaultAll);
}
foreach (var item in envNames)
{
var localEnv = new LoginEnvironment();
localEnv.LoginEnvironmentID = item.LoginEnvironmentID;
localEnv.LoginEnvName = item.LoginEnvName;
listEnv.Add(localEnv);
}
return listEnv;
}
}