HRESULT: 0x80010105 (RPC_E_SERVERFAULT)

Hello,

My current project is using ASP.NET Webforms and we are using a COM component for some simulations.
During some UI integration tests, we got the error from the title: HRESULT: 0x80010105 (RPC_E_SERVERFAULT) during a call to the COM component.
Obviously, I tried reproducing the error on my development machine but the error was nowhere to be found - everything worked!
After a quick search on Google, I've encountered this article (http://msdn.microsoft.com/en-us/magazine/cc163544.aspx) where the solution is presented: set the AspCompat="true" in the @Page directive of the ASP.NET page.
Once I've done that, the error dissapeared!

Hope it helps some of you... :)

Happy coding!

Oracle ADO.NET EF with transactions

                 ModelContext.Connection.Open();
                 using (var tx = ModelContext.Connection.BeginTransaction())
                 {
                     try
                     {
                         // do stuff...
                         tx.Commit();
                         return true;
                     }
                     catch
                     {
                         tx.Rollback();
                         throw;
                     }
                     finally
                     {
                         if (ModelContext.Connection != null)
                             ModelContext.Connection.Close();
                     }
                 }

How to model a thought/idea (in AI context)?

That is the (ultimate) question for AI...

Derived question: How can we model the thought that gave birth to that (or any) question?

XBox Live funny error

So... where's my prize? :)

ASP.NET DropDownList does not fire SelectedIndexChanged

Hello,

In one of my working projects - an ASP.NET WebForms, I had a DropDownList control (with AutoPostBack = "true") that was bound to  a ADO.NET EntityFramework entities collection. When the tester tested the webform, the DDL was posting but the default element (which had ID = 0) was selected and the handler for SelectedIndexChanged in the code-behind was not fired.
After some banging my head to my desk for a couple of hours (because other DDLs were working fine), I looked inside the data that was bound to the DDL. And to my surprise, that specific row in the (Oracle) table had the ID = 0, and therefore, no SelectedIndexChanged.

So, check your data too before banging your head to the office desk! :)

Hope it helps someone ... someday...

ADO.NET EF solution for "The table/view ' does not have a primary key defined. The key has been inferred and the definition was created as a read-only table/view."

Hey there,

In my current project we are using the ADO.NET Entity Framework (for multiple run-time environments: .NET & COM - see previous post for details) and we got the error from the title when generating the entities from database:The table/view '' does not have a primary key defined. The key has been inferred and the definition was created as a read-only table/view.
In order to fix this, you should do this:
- create a non-nullable PK in a table.
- create a virtual non-nullable "PK" and ID in a view.

For Micosoft SQL Server you can use the ROW_NUMBER() function and for Oracle (11g) you can use rownum but that's not enought (I think for MS SQL Server also). You have to add a constraints (yes, views can have constraints):

CREATE OR REPLACE FORCE VIEW "SCHEMA"."VIEW_NAME" ("ID", "COL1", "COL2")
AS
SELECT ROWNUM, COL1, COL2 FROM TABLE
WITH READ ONLY;

alter view VIEW_NAME add constraint id_pk primary key (ID) disable novalidate;.

 Hope it helps you sometime. :)

Bonus tip: if your view does a UNION (as it was in my case) the second SELECT will have something like SELECT ROWNUM+(SELECT COUNT(*) FROM TABLE1). ;)

[COM] Pass .NET object array to COM

Hey there,
In the life of a .NET developer comes a day when is needed to interact with COM. In this post I will try to explain a way to pass .NET array of objects (can be common CLR objects) to COM environment.
First, you have to expose the .NET object(s) to COM (I will name it Type) by implementing an interface (IType) and decorating them as follows:
[ComVisible(true)]
[System.Runtime.InteropServices.InterfaceTypeAttribute(System.Runtime.InteropServices.ComInterfaceType.InterfaceIsDual)]
[Guid("104136e6-af1f-4719-985a-8b65e588e4bb")]
public interface IType


[ComVisible(true)]
[System.Runtime.InteropServices.ClassInterfaceAttribute(System.Runtime.InteropServices.ClassInterfaceType.None)]
[Guid("85aff115-b4ad-473a-9774-285cb1b9ef28")]    [System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)]
public partial class Type : IType

Also, you will need some kind of context where all the operations will be hosted. This context, which is a normal C#/.NET class, will also have to be exposed to COM.
Now, lets say you want to pass an IType[] to COM. If you write your method from the context to return an IType[] (public IType[] GetData(string filter)), in the .tlh file (that is generated for C++) the method will have a parameter SAFEARAY**. You could use this but you will have to know the dimension of the array before invoking the GetData(...) method (plus I don't think you will be able to see the COM types in the SAFEARRAY when you'll write your code).

My solution is using the callback idea. I will write the method in the .NET context returning just an IType and using some magic in C++ and C#/.NET I will invoke GetData method multiple times and return the elements one by one. I will also exppose a boolean isFinished parameter as output.
In the .NET code, in order to maintain the state of some variable (like static in C/C++ functions) you can use [ThreadStaticAttribute] or ThreadLocal like this:
internal static class GetMany<T,IT>
        where T : class
        where T : IT
{
     [ThreadStatic]
     private static int counter = 0;

     [ThreadStatic]
     private static IList<IT> collection;

     public static IT Get(ObjectQuery<T> query, string predicate, string orderby, out bool isFinished)
     {
         isFinished = true;

         if (collection == null)
         {
             if (!string.IsNullOrEmpty(predicate))
                 query = query.Where(predicate);

             if (!string.IsNullOrEmpty(orderby))
                 query = query.OrderBy(orderby);

             collection = query.Cast<IT>().ToList();
         }

         if (collection == null || counter >= collection.Count())
         {
             collection = null;
             counter = 0;
             return default(IT);
         }

         isFinished = false;
         return collection[counter++];
     }
}
In the context method GetData I will invoke the method Get from GetMany like this:
GetMany<Type, IType>.Get(collection, predicate, orderby, out isFinished);
In my project case the collection was an ADO.NET EF collection and the predicate and orderby strings were passed from C++.

In .tlh file you will get a function like HRESULT GetData(BSTR predicate, BSTR orderby, VARIANT_BOOL* isFinished, IType* entity); where IType is:
struct __declspec(uuid("104136e6-af1f-4719-985a-8b65e588e4bb"))
IType : IDispatch.

All we need to do now is to write some code to invoke the GetData method multiple times. For this, since I am using VS2010 with some of the C++ 11 features supported (e.g. auto, lambdas, static_assert, etc), I will write a templated function using a std::function as a callback (just like Func if I may :) ):

template<typename T>
void import(std::vector<T>& container, std::function<HRESULT (VARIANT_BOOL* isFinished, T& result)> action)
{
    VARIANT_BOOL isFinished = FALSE;

    while (!isFinished)
    {
        T result;
        if (!SUCCEEDED(action(&isFinished, result)))
            throw;

        if (result != nullptr)
            container.push_back(result);
    }
}


When I want to invoke the actual code, I would write:
std::vector<ITypePtr> collection;         
import(collection ,
[&ptr, &predicate, &orderby] (VARIANT_BOOL* isFinished, ITypePtr& result)->
        HRESULT {
            auto hr = testResult.CreateInstance(__uuidof(Type));
            return ptr->GetData(predicate, orderby, isFinished, &result);  
});


After this line, the collection will contain all ITypePtr passed from .NET.

That's all! No more SAFEARRAY**! :)