How to use IList with HQL Query and NHibernate?

Question

I'm trying execute a HQL query with NHibernate. When I try execute query it throws an exception and I can't understand what is the problem.

HQL Query.

public class UsuarioDAO : ImplementacaoPersist<Usuario>{

        public IList<Usuario> findByText(string text) {
            ISession _session = BDConnect.openSession();
            IList<Usuario> list = (IList<Usuario>)_session.CreateQuery("from Usuario u WHERE u.nome LIKE :nome OR u.login LIKE :login")
                                                                        .SetParameter("nome", "%" + text + "%")
                                                                        .SetParameter("login", "%" + text + "%");
            return list;
        }
    }

exception

System.Transactions Critical: 0 : <TraceRecord xmlns="http://schemas.microsoft.com/2004/10/E2ETraceEvent/TraceRecord" Severity="Critical"><TraceIdentifier>http://msdn.microsoft.com/TraceCodes/System/ActivityTracing/2004/07/Reliability/Exception/Unhandled</TraceIdentifier><Description>Unhandled exception</Description><AppDomain>ControleUsuarios.vshost.exe</AppDomain><Exception><ExceptionType>System.InvalidCastException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</ExceptionType><Message>Unable to cast object of type 'NHibernate.Impl.QueryImpl' to type 'System.Collections.Generic.IList`1[ControleUsuarios.Domain.Usuario]'.</Message><StackTrace>   at ControleUsuarios.Implementacao.UsuarioDAO.findByText(String text) in c:\Users\fernando\Documents\Visual Studio 2012\Projects\ControleUsuarios\ControleUsuarios\Implementacao\UsuarioDAO.cs:line 18
   at ControleUsuarios.Form1.txtSearch_KeyUp(Object sender, KeyEventArgs e) in c:\Users\fernando\Documents\Visual Studio 2012\Projects\ControleUsuarios\ControleUsuarios\Form1.cs:line 80
   at System.Windows.Forms.Control.OnKeyUp(KeyEventArgs e)
   at System.Windows.Forms.Control.ProcessKeyEventArgs(Message&amp;amp; m)
   at System.Windows.Forms.Control.ProcessKeyMessage(Message&amp;amp; m)
   at System.Windows.Forms.Control.WmKeyChar(Message&amp;amp; m)
   at System.Windows.Forms.Control.WndProc(Message&amp;amp; m)
   at System.Windows.Forms.TextBoxBase.WndProc(Message&amp;amp; m)
   at System.Windows.Forms.TextBox.WndProc(Message&amp;amp; m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message&amp;amp; m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message&amp;amp; m)
   at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
   at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG&amp;amp; msg)
   at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Application.Run(Form mainForm)
   at ControleUsuarios.Program.Main() in c:\Users\fernando\Documents\Visual Studio 2012\Projects\ControleUsuarios\ControleUsuarios\Program.cs:line 16
   at System.AppDomain._nExecuteAssembly(RuntimeAssembly 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.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()</StackTrace><ExceptionString>System.InvalidCastException: Unable to cast object of type 'NHibernate.Impl.QueryImpl' to type 'System.Collections.Generic.IList`1[ControleUsuarios.Domain.Usuario]'.
   at ControleUsuarios.Implementacao.UsuarioDAO.findByText(String text) in c:\Users\fernando\Documents\Visual Studio 2012\Projects\ControleUsuarios\ControleUsuarios\Implementacao\UsuarioDAO.cs:line 18
   at ControleUsuarios.Form1.txtSearch_KeyUp(Object sender, KeyEventArgs e) in c:\Users\fernando\Documents\Visual Studio 2012\Projects\ControleUsuarios\ControleUsuarios\Form1.cs:line 80
   at System.Windows.Forms.Control.OnKeyUp(KeyEventArgs e)
   at System.Windows.Forms.Control.ProcessKeyEventArgs(Message&amp;amp; m)
   at System.Windows.Forms.Control.ProcessKeyMessage(Message&amp;amp; m)
   at System.Windows.Forms.Control.WmKeyChar(Message&amp;amp; m)
   at System.Windows.Forms.Control.WndProc(Message&amp;amp; m)
   at System.Windows.Forms.TextBoxBase.WndProc(Message&amp;amp; m)
   at System.Windows.Forms.TextBox.WndProc(Message&amp;amp; m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message&amp;amp; m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message&amp;amp; m)
   at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
   at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG&amp;amp; msg)
   at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Application.Run(Form mainForm)
   at ControleUsuarios.Program.Main() in c:\Users\fernando\Documents\Visual Studio 2012\Projects\ControleUsuarios\ControleUsuarios\Program.cs:line 16
   at System.AppDomain._nExecuteAssembly(RuntimeAssembly 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.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()</ExceptionString></Exception></TraceRecord>
The program '[2584] ControleUsuarios.vshost.exe: Program Trace' has exited with code 0 (0x0).
The program '[2584] ControleUsuarios.vshost.exe: Managed (v4.0.30319)' has exited with code -1 (0xffffffff).

Answer 1

You are casting a query object to a List. This is not how you should get your query executed.

From your log: System.InvalidCastException then Unable to cast object of type 'NHibernate.Impl.QueryImpl' to type 'System.Collections.Generic.IList.

See the doc. Your code should be:

var list = _session
    .CreateQuery("from Usuario u WHERE u.nome LIKE :nome OR u.login LIKE :login")
    .SetParameter("nome", "%" + text + "%")
    .SetParameter("login", "%" + text + "%")
    .List<Usuario>();

Side note: I guess your sample code is not more than a sample, but just in case, make sure your actual code does not forget to close/dispose the session.

You may also consider using other querying APIs than HQL. Personally, I tend to use HQL only with named queries. In code, I am mostly using linq-to-nhibernate.

using NHibernate.Linq;
...

var list = _session
    .Query<Usuario>()
    .Where(u => u.nome.Contains(text) || u.login.Contains(text))
    .ToList();

But you could also use Criteria or QueryOver.