Re: Passing values between classes - C# Discussion Boards

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Re: Quick Constructor Question

GParkings29-Feb-12 22:47

GParkings

29-Feb-12 22:47

Personally, i would be asking why I wanted to do this.

I assume that the SetupViewModel method requires the DataEntity property to be set.

What, immediately becomes apparent is that you have a method, whose body is declared in the subclass, acting on data, declared in the subclass after all logic in the base class constructor has been performed .. Is it really necessary to have SetupViewModel as an abstract in the base as it is entirely specific to the subclass?

If you need to ensure setup functionality has occurred before other logic in the base class is run you could consider a protected _isInitialized boolean field alongside the abstract SetupViewModel method. Then check _isInitialized before performing logic and if it is false, call SetupViewModel (which, since the subclass constructor will have run by this point, will be able to access DataEntity )

An alternative is to consider whether all subclasses would ahve a common base for their data entity, in which case the base class could have a field of this type (or a collection of this type) and the field could be passed into the base constructor.

A further alternative is to make _ViewModelBase generic (_ViewModelBase<t> ) with a DataEntity of type T and, again, pass this to the base class

Pedis ex oris
Quidquid latine dictum sit, altum sonatur

Re: Quick Constructor Question

BobJanova1-Mar-12 5:27

BobJanova

1-Mar-12 5:27

You can't. Very annoying it is too, in certain circumstances. (Particularly if the constructor calls some virtual methods, in which case DataEntity won't be available in those either.) In a simple case like this (where a view model wants to store a 'something') I'd make _ViewModelBase (that underscore makes me feel ill, by the way) generic and have it store the data object in its constructor.

Passing values between classes

CCodeNewbie29-Feb-12 10:33

CCodeNewbie

29-Feb-12 10:33

Hi,

I think I have become a little lost while trying to pass values from one class to another and, having researched reasons why my code isn't working, am now going in circles (I really need to start documenting attempted methods).

OK, so I have this code which gets some user details using impersonation (thanks to Luc for making me work harder finding an answer)

public class UInfo
    {
    [DllImport("advapi32", SetLastError=true), SuppressUnmanagedCodeSecurityAttribute]
    static extern int OpenProcessToken(System.IntPtr ProcessHandle, int DesiredAccess, ref IntPtr TokenHandle);

[DllImport("kernel32", SetLastError=true), SuppressUnmanagedCodeSecurityAttribute]
static extern bool CloseHandle(IntPtr handle);
[DllImport("advapi32.dll", CharSet=CharSet.Auto, SetLastError=true)]
public extern static bool DuplicateToken(IntPtr ExistingTokenHandle, int SECURITY_IMPERSONATION_LEVEL, ref IntPtr DuplicateTokenHandle);

public const int TOKEN_DUPLICATE = 2;
public const int TOKEN_QUERY = 0X00000008;
public const int TOKEN_IMPERSONATE = 0X00000004;

    public void UsInfo(string[] args)
    {
        IntPtr hToken = IntPtr.Zero;
        IntPtr dupeTokenHandle = IntPtr.Zero;
        Process proc = Process.GetProcessById(2568);
        if
        {
           OpenProcessToken(proc.Handle,TOKEN_QUERY|TOKEN_IMPERSONATE|TOKEN_DUPLICATE, ref hToken) != 0)
        {
        WindowsIdentity newId = new WindowsIdentity(hToken);

            try
            {
                const int SecurityImpersonation = 2;
                dupeTokenHandle = DupeToken(hToken,  
                SecurityImpersonation);
                if(IntPtr.Zero == dupeTokenHandle)
                {
                    string s = String.Format("Dup failed {0}, 
                    privilege not held",
                        Marshal.GetLastWin32Error());
                        throw new Exception(s);
                }

                WindowsImpersonationContext impersonatedUser =  
                newId.Impersonate();
                IntPtr accountToken =  
                WindowsIdentity.GetCurrent().Token;
                string Token = accountToken.ToString();
                string WinID = 
                WindowsIdentity.GetCurrent().Name;
                string IsAuthd =  
                newId.IsAuthenticated.ToString();
                string AuthType = newId.AuthenticationType;
                string IsGuest = newId.IsGuest.ToString();
                string SIDNo = newId.Owner.ToString();
                string SIDPlain = 
                newId.Owner.TranslatTAccount)).ToString());
           }
           finally
           {
           CloseHandle(hToken);
           }
        }
        else
        {
            string s = String.Format("OpenProcess Failed {0}, 
            privilege not held", Marshal.GetLastWin32Error());
            throw new Exception(s);
        }
    }
    static IntPtr DupeToken(IntPtr token, int Level)
    {
        IntPtr dupeTokenHandle = IntPtr.Zero;
        bool retVal = DuplicateToken(token, Level, ref 
        dupeTokenHandle);
        return dupeTokenHandle;
    }
}//from Willy Denoyette [MVP] http://bytes.com/topic/c-sharp/answers/463942-using-openprocesstoken

but I need to put the string values retrieved in to my service's code:-

public partial class Service : ServiceBase
{
     public void OnTimedEvent(object source, ElapsedEventArgs e)
     {
      // do some sql connection stuff
      in.Parameters.Add("@UAuthType", SqlDbType.NVarChar,40)   
      .Value = AuthType;// I dont get Uinfo.AuthType as being an available value
      in.Parameters.Add("@UAuth", SqlDbType.NVarChar, 40)
      .Value = IsAuthd;
      // the code doesn't errror, there are just no values (not even null) written to the db.

I have tried using public const string AuthType = ""; but still nothing writes to the db.

Could someone please point me in the right direction on this? I have seen a lot of articles using this kind of thing from http://social.msdn.microsoft.com/forums/en-US/csharpgeneral/thread/02d7555b-b600-4b0e-aa76-6b2d976e6c44/

public class Customer
{
    private string _name;

    public string Name
    {
        get
        {
            return _name;
        }
        set
        {
            _name = value;
        }
    }
}

but surely there has to be a more concise way to return multiple values?

Thanks for your time.