Exception when using IQueryable First() and FirstOrDefault()

Exception when using IQueryable First() and FirstOrDefault()

Postby freakshow » Tue 09 Dec 2008 18:20

dotConnect version: 5.00.16

Trying to execute a codeblock that uses First or FirstOrDefault methods of the IQueryable interface throws an exception. This occours after the table is casted.

Example code:
Code: Select all
ITable table2 = ctx.GetTable(typeof(Employee));
IQueryable empTable2 = table2.Cast();
IEmployee employee2 = empTable2.FirstOrDefault();


Exception message:
Object of type 'System.Func`2[System.Data.IDataRecord,DevArtLinqToOracleExceptions.Employee]' cannot be converted to type 'System.Func`2[System.Data.IDataRecord,DevArtLinqToOracleExceptions.IEmployee]'.

at System.RuntimeType.CheckValue(Object value, Binder binder, CultureInfo culture, BindingFlags invokeAttr)
at System.Reflection.MethodBase.CheckArguments(Object[] parameters, Binder binder, BindingFlags invokeAttr, CultureInfo culture, Signature sig)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at Devart.Data.Linq.Provider.c.a(Type A_0, SqlNode A_1, d A_2, m A_3)
at Devart.Data.Linq.Provider.DataProvider.a(Expression A_0)
at Devart.Data.Linq.Provider.DataProvider.h(Expression A_0)
at Devart.Data.Linq.DataQuery`1.System.Linq.IQueryProvider.Execute[S](Expression expression)
at System.Linq.Queryable.FirstOrDefault[TSource](IQueryable`1 source)
at DevArtLinqToOracleExceptions.Program.Main(String[] args) in g:\tmp\DevartTest2\ConsoleApplication1\Program.cs:line 62
at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()



This bug was discovered after you had fixed issues reported by me in this post: http://devart.com/forums/viewtopic.php?t=13248


Console app code to reproduce the exception:

Code: Select all
using System;
using System.Data.Linq.Mapping;
using System.Linq;
using Devart.Data.Linq;

namespace DevArtLinqToOracleExceptions
{

    /*
    1. Create a console application
    2. Make sure project references DevArt.Data.Linq, DevArt.Data.Oracle, etc...
    3. Change connectionstring below
    4. Run Oracle create script for test table:
     
    CREATE TABLE EMPLOYEE ("ID" NUMBER NOT NULL ENABLE, "NAME" NVARCHAR2(50));
    INSERT INTO EMPLOYEE (ID, NAME) VALUES (1, 'John Johnson');
    INSERT INTO EMPLOYEE (ID, NAME) VALUES (2, 'Jane Doe');
    COMMIT;

   
     */

    class Program
    {
        static void Main(string[] args)
        {
            using (EntityContext ctx = new EntityContext())
            {
                // All the scenarios below works with Linq to Sql,

                // Scenario 1 (using FirstOrDefault without interface): Works

                var firstEmployee = (from emp in ctx.GetTable()
                                     select emp).FirstOrDefault();

                Console.WriteLine(firstEmployee.Id);

               
                // Scenario 2 (using cast with interface, but without FirstOrDefault): Works.

                ITable table1 = ctx.GetTable(typeof(Employee));
                IQueryable empTable1 = table1.Cast();

                var qry = from e in empTable1
                          select e;

                foreach (IEmployee employee in qry)  // Throws exception here
                {
                    Console.WriteLine(employee.Id);
                    break;
                }


                // Scenario 3 (using cast with interface and using method FirstOrDefault): Throws exception
                // Object of type 'System.Func`2[System.Data.IDataRecord,DevArtLinqToOracleExceptions.Employee]'
                // cannot be converted to type 'System.Func`2[System.Data.IDataRecord,DevArtLinqToOracleExceptions.IEmployee]'.

                ITable table2 = ctx.GetTable(typeof(Employee));
                IQueryable empTable2 = table2.Cast();

                IEmployee employee2 = empTable2.FirstOrDefault();
               
            }

            Console.ReadLine();
        }
    }

    [Provider(typeof(Devart.Data.Oracle.Linq.Provider.OracleDataProvider))]
    public class EntityContext : Devart.Data.Linq.DataContext
    {
        public EntityContext()
            : base("User Id=xx;Password=xx;Server=xx;Direct=True;Sid=xx") { }
    }

    public interface IEmployee
    {
        int Id { get; set; }
        string Name { get; set; }
    }

    [Table(Name = "EMPLOYEE")]
    public class Employee : IEmployee
    {
        [Column(Name = "ID", IsPrimaryKey = true)]
        public int Id { get; set; }

        [Column(Name = "NAME")]
        public string Name { get; set; }
    }
}
freakshow
 
Posts: 12
Joined: Mon 28 Jul 2008 12:38
Location: Oslo, Norway

Postby AndreyR » Wed 10 Dec 2008 09:35

We have reproduced the error. I will let you know about the results of the investigation.
AndreyR
Devart Team
 
Posts: 2919
Joined: Mon 07 Jul 2008 13:16

Postby AndreyR » Wed 14 Jan 2009 16:10

This issue is fixed. Look forward to the next build.
AndreyR
Devart Team
 
Posts: 2919
Joined: Mon 07 Jul 2008 13:16


Return to LinqConnect (LINQ to SQL support)