Cannot implicitly convert type

here is the rest of the code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Linq;

namespace CPMS_DAL.Framework
{
    public interface IENTBaseEntity
    {
        DateTime CreateDate { get; set; }
        int CreateByID  { get; set; }
        DateTime UpdateDate { get; set; }
        int UpdateByID { get; set; }
        Binary Version { get; set; }
    }
}
--------------------------------------------------
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using CPMS_DAL.Framework;

namespace CPMS_DAL
{
    public partial class cl_Accounts : IENTBaseEntity
    {
        #region IENTBaseEntity Members

        DateTime IENTBaseEntity.CreateDate
        {
            get
            {
                throw new NotImplementedException();
            }
            set
            {
                throw new NotImplementedException();
            }
        }

        int IENTBaseEntity.CreateByID
        {
            get
            {
                throw new NotImplementedException();
            }
            set
            {
                throw new NotImplementedException();
            }
        }

        DateTime IENTBaseEntity.UpdateDate
        {
            get
            {
                throw new NotImplementedException();
            }
            set
            {
                throw new NotImplementedException();
            }
        }

        int IENTBaseEntity.UpdateByID
        {
            get
            {
                throw new NotImplementedException();
            }
            set
            {
                throw new NotImplementedException();
            }
        }

        System.Data.Linq.Binary IENTBaseEntity.Version
        {
            get
            {
                throw new NotImplementedException();
            }
            set
            {
                throw new NotImplementedException();
            }
        }

        #endregion
    }
}
----------------------------------

i still need to see the type/class definition of tbl_Account and also the client code where you try to make use of these classes.

you have everything.  I can't get it to compile.  The tbl_account table has fields defined with exactly the same name and definition in the interface.

Having the same fields does not make one class equal to, or even convertible to, another class.

paraphrasing what psasik said,

typeof(List<CPMS_DAL.tbl_Account>)  != typeof(List<CPMS_DAL.cl_Accounts>)

simply because:

typeof(CPMS_DAL.tbl_Account)  != typeof(CPMS_DAL.cl_Accounts)

David

Okay, if they are exactly the same name and exactly the same definition, then how do I get them to be equal?  I'm pretty new at this so clarification is really helpful to me.

Thanks.

It's a real quandry that hits everyone as they try to develop well organized and layered software. The upshot is, unless you share a class between the two layers, so that the namespace.classname is identical, you can't do what you are trying to do. Of course, then you are violating the separation between layers you are trying to achieve.

The answer is, "Don't code to implementations (classes), code to abstractions (interfaces)."

Create an interface that contains all of the properties, have the classes in both layers implement that interface, then program against that interface, rather than against the classes. This way, the objects in both layers can evolve independently, as long as they honor the contract (interface) they signed up for.

David

(To your last question: Even having the same name is not enough, since the namespace can be thought of as part of the name.)

dwr

Okay.  I've defined all properties in the interface IENTBaseEntity, I've implemented them all in cl_Accounts and tbl_AccountData, but I still get the same error.

So, have you change the code to work with the abstraction, IENTBaseEntity, instead of cl_Accounts and tbl_Accounts?

For example,

       public override List<cl_Accounts> Select()
       {
           using (CPMSDataContext db = new CPMSDataContext())
           {
               return db.sp_Accounts_SelectAll().ToList();  ---------returns error.
           }
       }

This will now return a List<IENTBaseEntity>.

David

Did you change you generic Lists' declarations?

List<CPMS_DAL.tbl_Account>    should be:   List<CPMS_DAL.IENTBaseEntity>

and

List<CPMS_DAL.cl_Accounts>   should be:    List<CPMS_DAL.IENTBaseEntity>

do you mean like this?

namespace CPMS_DAL.Framework
{
    public class tbl_AccountsData : ENTBaseData<IENTBaseEntity>
    {
        public override List<IENTBaseEntity> Select()
        {
            using (CPMSDataContext db = new CPMSDataContext())
            {
                return db.sp_Accounts_SelectAll().ToList();
            }
        }

        public override cl_Accounts Select(int id)
        {
            using (CPMSDataContext db = new CPMSDataContext())
            {
                return db.sp_Accounts_SelectSingle(id).SingleOrDefault();
            }
        }

        public override void Delete(CPMSDataContext db, int id)
        {
            db.sp_Accounts_Delete(id);
        }
    }
}

Yes.

I'm still getting the same error for this code:
namespace CPMS_DAL.Framework
{
    public class tbl_AccountsData : ENTBaseData<IENTBaseEntity>
    {
        public override List<IENTBaseEntity> Select()
        {
            using (CPMSDataContext db = new CPMSDataContext())
            {
                return db.sp_Accounts_SelectAll().ToList();
            }
        }

        public override IENTBaseEntity Select(int id)
        {
            using (CPMSDataContext db = new CPMSDataContext())
            {
                return db.sp_Accounts_SelectSingle(id).SingleOrDefault();
            }
        }

        public override void Delete(CPMSDataContext db, int id)
        {
            db.sp_Accounts_Delete(id);
        }
    }
}

Its telling me "Cannot implicitly convert type 'System.Collections.Generic.List<CPMS_DAL.tbl_Account>' to 'System.Collections.Generic.List<CPMS_DAL.Framework.IENTBaseEntity>'"

Sam, i tried to piece together the code you've posted here but came up short. Missing classes... methods etc. Would put all the related classes and interfaces into a single file and post it here? There should just be a single usings' group for example... if i can put this into Snippet Compiler for example, i might be able to help you. Right now, i'm a bit lost. Anyoneis, do you concur?

I've attached a file that contains all code for the above and table definition to tbl_accounts and the stored procedures it uses.

It's still missing the definition for the CPMSDataContext class. Can you include that?

This is created by Visual Studios.

Yes psasik, I agree that we needed to see this other file. The data context class, tbl_Account, is a partial class, so I think you should be able to extend it wihtout touching the auto-generatedI code. I can't try this right now, but perhaps psasik can give you more direction.

Perhaps the cleanest way to do this will be to create a new project for th einterface definitions, and then reference that assembly from your application and from your DAL. Let's say you call the project ENTInterfaces. There will be an interface called ENTInterfaces.IENTBaseEntity. cl_Account should implement this interface.

What I am not sure of is if you can go to the DAL, refernce the ENTInterfaces assembly, and create a file called tbl_Account, which looks something like this

     using ENTInterfaces
    public partial class tbl_Accounts : IENTBaseEntity
    {}

This is off the top of my head. I can't play with it right now. Good Luck!!!

i'm busy as well Sam. And what's worse, i'm still using .Net 2.0 at work. i need to do this at home with SharpDevelop!

But, as another strategy for trying to solve this in the meantime: Create a simpler version of these classes. Such as interfaces with two members instead of a dozen. Give yourself less code to look at, and us. ;-)

Once we get a simple model figured out, applying it to the more complex version will be easy.

I started out with only 4 members but you guys said I had to define all the fields in my table in the interface now you're telling me it's too many?  How can this be?  The dataContext is auto generated from visual studios so I don't think the problem is there. I believe it's in the interface and how it's being used.  This is based on the example I'm using from WROX "ASP.NET 3.5 Enterprise Application Development with Visual Studio 2008".  Maybe if one of you have access to this book you can see where the code is driving at.

I don't know how to make this simpler.  I really think you are looking in the wrong direction.  Anyoneis can you take a look as soon as you can?  I'm trying to research on my end as well, maybe there is something small that we are missing.

OK, I found the book at Books 24X7!

Looking at figure 2-6 in the book, he is using the Entity objects (created by the ORM ) in the BLL. That is, DataContext.tbl_Account would be used in your BLL layer. Where did clAccount come from?

He has later on the code below. Notice he is using the equivalent of your tbl_Account object and passing that (or a list of those)back to the BLL . You have introduced another class, cl_Account, but there is no automatic conversion between the two.

David

public class ENTUserAccountData :ENTBaseData<ENTUserAccount>
{
     public override List<ENTUserAccount>Select()
 
{
     using (HRPaidTimeOffDataContext db =new
               HRPaidTimeOffDataContext())
     {
          return db.ENTUserAccountSelectAll().ToList();
     }
}
 
public override ENTUserAccount Select(int id)
     {
          using (HRPaidTimeOffDataContext db =new
                    HRPaidTimeOffDataContext())
          {
               return db.ENTUserAccountSelectById(id).SingleOrDefault();
          }
     }
}
                                              

1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
20:
21:

(Admittedly, there is stuff I don't understand about his solution yet...)

"That's it. Each and every table will have an entity class generated by the ORM Designer, and a Data class to handle communication to the database and the BLL. "

I think this is the Repository pattern, as illustrated in Scottgu's tutorial available at http://tinyurl.com/aspnetmvc.

His <tableName>Data class just passes the ORM entities back and forth between the BLL and the DAL.

(Have I read far enough in the book?)

David

I think the part you are missing is below - adding to the paretial classes created by the ORM designer.

"We want all of our entity classes that are created by the ORM Designer to implement this interface. You could open the file that contains all the entity objects and modify the class declaration to inherit from this interface, but the next time you regenerate a table's class from the ORM Designer you would have to remember to modify the result. This is where partial classes come in handy. You can create another file and then create a partial class that is named the same as the entity class and have that inherit the correct interface. That way, you can regenerate the entity class as often as you want and not have to worry about customizing its code. The goal is to never have to customize the auto-generated code because you will find yourself doing this a lot.
The partial classes all go into one class file called CustomizedEntities in the root folder. Right-click on the DAL project and select Add New Item to add this class to the root folder. You need to add a using statement to reference the V2.PaidTimeOffDAL.Framework namespace and replace the default code with this:"

using V2.PaidTimeOffDAL.Framework;
 
namespace V2.PaidTimeOffDAL
{
      public partial class ENTUserAccount :IENTBaseEntity {}
}
                                              

1:
2:
3:
4:
5:
6:

I had this but everyone said I had to implement it in another question I had open here.  I changed it to cl_accounts to differentiate between the table and the class.  If I remove all the get set for each field I will have a build error that says IENTBaseEntity is not implemented.

namespace CPMS_DAL
{
    public partial class cl_Accounts : IENTBaseEntity
}

Unless I am mistaken, the autogenerated class is not cl_accounts, but CPMS_DAL.tbl_Account. tbl_Account is the partial class that you must extend, by marking it as implementing the interface.

I've changed it to just as you have it above and made sure all the references have the new change:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using CPMS_DAL.Framework;

namespace CPMS_DAL
{
    public partial class tbl_Accounts : IENTBaseEntity
    {
    }
}

and now I have my very initial problem, I'm getting errors saying that CPMS_DAL does not implement interface.

I have in place everything that the example states.

and I can't get to http://tinyurl.com/aspnetmvc because my job has it blocked.  My boss won't unblock it.  Can you send it to me in a document?

For Guthrie's example, try http://www.wrox.com/WileyCDA/Section/id-321793.html

or http://aspnetmvcbook.s3.amazonaws.com/aspnetmvc-nerdinner_v1.pdf

Back to your problem: What is the exact error?

originally I started with the same exact code structure as in the book.  the first error I got was about implementation of the interface.  I had another open question for this.  Everyone on that said I had to implement the interface in the clase.  I did so the next error I got was Cannot implicitly convert type 'System.Collections.Generic.List<CPMS_DAL.tbl_Account>' to 'System.Collections.Generic.List<CPMS_DAL.tbl_Accounts>'".  I thought this was confusing so to narrow it down I changed the partial class to cl_Accounts.  that is when I saw the problem.  ---- I want to stop here because I just solved the problem....

My table in sql is tbl_account and the partial class is named tbl_accounts.  the extra 's' was throwing it off.  I changed the partial clase to tbl_account and implemented it and all seems right with the world.  I can't believe this is how it works.  If you could explain to me why it works this way I will give you all the point plus.

Maybe it's not solved?  I'm only getting a successful build.  I am in the linq to sql process or the ORM I'm droping the stored procedures onto the table and maybe that is why the class has to be of the same name?  what I noticed is that of the five members in the interface only 2 need to be implemented in the partial class.  I wonder why?

any imput from you about this would be amazing...please don't leave the question yet.  I need to understand this.

Hmmm I am having my answers dropped - I responded 5 or 10 minutes ago.  Anyways, I would guess that the other three properties are already part of the autogenerated tbl_Account object?
 

That's interesting... I'm going to have to look into that one until I understand it.

Ciao,

David

I was able to solve it.  the minutia of details have to be exact.  starting to hate microsoft.