“Failed to enable constraints. One or more rows  contain values violating non-null, unique, or foreign-key  constraints.”

when using ADO.NET Datasets ?

Tthis is an incredibly useful message isn’t it ?

So what can you do to spare you some headaches ? Retrieve a more useful message sure !

You have to know that a Datatable object have a “HasError” property, this property allows you to know if the datatable has one ore more rows in error.

When HasError is true, you can retrieve the rows havin an error with the DataTable’s “GetErrors()” method wich return an array with all datarow having an error.

The “in errror” rows can inform you about errors with the “RowError” property.

Here is a simple helper class which can be used to debug a single DataTable or an entire DataSet:

using System;
using System.Data;

public class DataSetErrorRevealer
{

   /// <summary>
   /// Get errors on rows of a DataTable
   /// </summary>
   /// <param name="errorDataTable">The DataTable to be checked</param>
   public static void RevealTableErrors(DataTable errorDataTable)
   {
      if (errorDataTable == null)
      {
         Console.WriteLine("The provided DataTable object is null");
         return;
      }

      if (errorDataTable.HasErrors)
      {
         DataRow[] rowsInError = errorDataTable.GetErrors();
         if (rowsInError.Length <= 0)
         {
            Console.WriteLine("There is no problem with table {0}", errorDataTable.TableName);
         }
         else
         {
            foreach (DataRow errorRow in rowsInError)
            {
               Console.WriteLine(errorRow.RowError);
            }
         }
      }
   }

   /// <summary>
   /// Get errors on row for all tables of a DataSet
   /// </summary>
   /// <param name="errorDataSet">The Dataset to be checked</param>
   public static void RevealDataSetErrors(DataSet errorDataSet)
   {
         if (errorDataSet == null)
         {
            Console.WriteLine("The provided DataSet is null");
            return;
         }

         foreach (DataTable errorTable in errorDataSet.Tables)
         {
            RevealTableErrors(errorTable);
         }
      }
   }

Use it this way :

   TestDataSet dataset = new TestDataSet();
   try
   {
      using (SqlConnection sqlCon = new SqlConnection("MyConnectionString"))
      {
         SqlCommand sqlComm = sqlCon.CreateCommand();
         sqlComm.CommandType = CommandType.StoredProcedure;
         sqlComm.CommandText = "Select Stored procedure";
         SqlDataAdapter sqlDa = new SqlDataAdapter(sqlComm);
         sqlDa.Fill(dataset);
      }
   }
   catch (Exception ex)
   {
   // Will provide the error message :
   // "Failed to enable constraints. One or more rows
   // contain values violating non-null, unique,
   // or foreign-key  constraints."
   Console.WriteLine("Error : {0}", ex);

   // will provide a more helpful message
   DataSetErrorRevealer.RevealDataSetErrors(dataset);
   }

If you prefer, you can use an extension method :

using System.Data;
using System;

public static class DataSetExtensions
{
   public static void RevealErrors(this DataSet errorDataSet)
   {
      if (errorDataSet == null)
      {
         Console.WriteLine("The provided DataSet is null");
         return;
      }

      foreach (DataTable errorTable in errorDataSet.Tables)
      {
         errorTable.RevealErrors();
      }
   }

   public static void RevealErrors(this DataTable errorDataTable)
   {
      if (errorDataTable == null)
      {
         Console.WriteLine("The provided DataTable object is null");
         return;
      }

      if (errorDataTable.HasErrors)
      {
         DataRow[] rowsInError = errorDataTable.GetErrors();
         if (rowsInError.Length <= 0)
         {
            Console.WriteLine("There is no problem with table {0}", errorDataTable.TableName);
         }
         else
         {
            foreach (DataRow errorRow in rowsInError)
            {
               Console.WriteLine(errorRow.RowError);
            }
         }
      }
   }
}

use :

catch (Exception ex)
{
   // will provide an helpful message
   dataset.RevealErrors();
}

Hope this helps !

According to the website, FreeImage (http://freeimage.sourceforge.net) is an Open Source library project for developers who would like to support popular graphics image formats like PNG, BMP, JPEG, TIFF and others as needed by today’s multimedia applications.

FreeImage is easy to use, fast, multithreading safe, compatible with all 32-bit versions of Windows, and cross-platform (works both with Linux and Mac OS X).

FreeImage is written in C++ but can be used in .NET by using a wrapper (which is provided on the site in the download section)

Using FreeImage in a .NET project

To use FreeImage with a .NET project, you have to include the native C++ library (FreeImage.dll) in the same folder as the executable or in a folder contained in the PATH variable (“%WINDIR%\System32” can be a good choice).
A good way to include the FreeImage dll in the executable’s folder is to add it to your visual studio projet, and set the Build Action property to “none” and the Copy to Output Directory property to “Copy always”

You have to add a reference to the wrapper library too, which is “FreeImageNET.dll”.

Now, using the library is easy.

Add an using directive:

using FreeImageAPI;

Check if the library is available :

if (!FreeImage.IsAvailable())
{
   Console.WriteLine("FreeImage.dll seems to be missing. Aborting");
   return;
}

Do something with your pictures:

FIBITMAP myImage= new FIBITMAP();
myImage= FreeImage.Load( [parameters] );

// some smart actions

Don’t forget to dispose your images when finished to use them

if (!myImage.IsNull
{
   FreeImage.Unload(myImage);
}
myImage.SetNull();

Well, this is nice but it still has a problem with that library (there is always one):

And with a x64 project ?

The executable you build has to be the same architecture as the library. The library is x86 so you can use it for win32 applications. What if you have (for some reasons) to build an x64 application?

In that case, you have to rebuild the library to target X64 architectures.

Here is how to do that with Visual Studio 2010 (I assume that it’s more or less the same procedure with other visual studio versions).

Grab the latest FreeImage sources on  the download site (go to the http://freeimage.sourceforge.net/download.html page and click to the link in the Source Distribution section. Once you have the sources, unzip the archive (obvious but…)

In the FreeImage folder there is a visual studio 2005 and a visual studio 2003 solutions, pick the 2005.

Convert the solution

Notice the compilation configuration

By default, Win32 is set : we don’t want that !

Go to the Configuration Manager

As you can see, all FreeImage libs are set to target the Win32 platform, we want 64 bits !

Add a new solution platform

Choose to target the x64 platform

Just select x64 then click OK

Close the manager

Build the solution (keyboard shortcut : ctrl-shift-B).

And at this point you will see that there is a problem, yes, you don’t really think it would be that easy

It seems that the compilation encounters a problem especially with the “LibOpenJpeg” project

So, to be sure, try to compile the library one at the same time

We see that it is the LibOpenJPEG the big source of problems :

A quick Google search allows to find a post on the Google user group for OpenJPEG that helps:
http://groups.google.com/group/openjpeg/browse_thread/thread/64b89cdb1a44bb3b/fd4db2f74c76db87?lnk=gst&q=x64#fd4db2f74c76db87

The problematic file is the “opj_include.h” wich use a keyword non supported by the x64 architecture (the “_asm” keyword if you want to know. It’s because the c++ compiler does not support inline x64 assembly)

We have to change :

/* MSVC does not have lrintf */
#ifdef _MSC_VER
static INLINE long lrintf(float f){
 int i;

 _asm{
 fld f
 fistp i
 };

 return i;
}
#endif

to

/* MSVC does not have lrintf */
#ifdef _MSC_VER
static INLINE long lrintf(float f){
#ifdef _M_X64
	return (long)((f>0.0f) ? (f + 0.5f):(f -0.5f));
#else
	int i;

	_asm{
		fld f
		fistp i
	};

	return i;
#endif
}
#endif

Now compile

The project compiles pretty well, there is some remaining warnings . . . but it works.

Now you can use that library (mine can be downloaded at  http://www.sambeauvois.be/Demos/FreeImage/x64/FreeImageX64.zip) in your x64 applications

Attention anyway : the library will be slower !

Additional links :

FreeImage download page : http://freeimage.sourceforge.net/download.html
FreeImage API documentation: http://freeimage.sourceforge.net/fnet/Index.html

My client has a Win server 2008 CA server for my developments

On this server I have a certificate template named “User Template”

My assignment was to request a certificate via an ASP.NET application.

After researches on how to do that, I found this blog post that helped me a lot : http://blogs.msdn.com/alejacma/archive/2008/09/05/how-to-create-a-certificate-request-with-certenroll-and-net-c.aspx

In my development environment, I create a request for a certificate by using  this code

 CERTENROLLLib.CX509CertificateRequestPkcs10Class request = new CERTENROLLLib.CX509CertificateRequestPkcs10Class();
 string templateName = "User Template";
 try
 {
    request.InitializeFromTemplateName(CERTENROLLLib.X509CertificateEnrollmentContext.ContextUser, templateName);
 }
 catch (Exception ex)
 {
   log.DebugFormat("Error InitializeFromTemplateName : message {0}, inner : {1}, stack : {2}, source : {3}, target : {4} ",
    ex.Message,
    ex.InnerException,
    ex.StackTrace,
    ex.Source,
    ex.TargetSite);
 }

And it worked just fine !

Then we moved the published solution to the staging environment, and the problems arrived . . .

It didn’t worked !

The error message said:

“CertEnroll::CX509CertificateRequestPkcs10::InitializeFromTemplateName: The requested certificate template is not supported by this CA. 0×80094800 (-2146875392)”

stack :

“at CERTENROLLLib.CX509CertificateRequestPkcs10Class.InitializeFromTemplateName(X509CertificateEnrollmentContext Context, String strTemplateName)”

We checked the security everywhere ( CA server, Certificate templates, IIS Account, …), give access to everyone on the CA, on the template, … without any success

Then, after days and hours of search and tests, I decided to re-read the method documentation : http://msdn.microsoft.com/en-us/library/aa377533%28v=VS.85%29.aspx

And I noticed the second parameter description:

strTemplateName [in]

Pointer to a BSTR variable that contains the Common Name (CN) of the template as it appears in Active Directory or the dotted decimal object identifier.

I had never tried using the dotted decimal object identifier, so i give it a shot.

I retrieved the object identifier on a certificate previously created with the “User Template”

On the CA server, I had a certificate request with the template “User Template”, so I right-click on it, go to All Tasks and click on the “View attributes/Extensions. . .” menu item.

A property windows opened, I go to the Extensions tab and click on the “Certificate Template Information” item.

In the information panel, I can see the famous dotted decimal object identifier between brackets.

I copy-paste this identifier in my code :

 CERTENROLLLib.CX509CertificateRequestPkcs10Class request = new CERTENROLLLib.CX509CertificateRequestPkcs10Class();
 string templateName = "1.3.6.1.4.1.311.21.8.3531346.8488945.6374567.164989.5001604.52.12582268.10747996";
 try
 {
    request.InitializeFromTemplateName(CERTENROLLLib.X509CertificateEnrollmentContext.ContextUser, templateName);
 }
 catch (Exception ex)
 {
    log.DebugFormat("Error InitializeFromTemplateName : message {0}, inner : {1}, stack : {2}, source : {3}, target : {4} ",
      ex.Message,
      ex.InnerException,
      ex.StackTrace,
      ex.Source,
      ex.TargetSite);
 }

I compiled, I tried in the development environment and it worked !!

(note: there is just a minimal change in my code since I put the “templateName” in a configuration file in order to be able to modify it)

So we moved the published solution to the staging environment,

retrieve the dotted decimal object identifier corresponding to the “User Template” on the staging CA server,

copy-pasted this identifier in the configuration file,

executed a “IISRESET” command and try to execute the application.

And it worked !

We can’t figured out why it worked in the development environment but not in the staging one while both are equals. So If anyone knows about it, please let me know.

So, don’t trust the template name and use the object identifier !

Visual C# 2010 default key bindings preview :

Shortcuts are grouped by category (debuging, refactoring, editing, navigation, …)

Here is the Visual Studio Keyboard shortcuts posters for C#:

Visual Studio 2010

• Download the pdf
• Go to the msdn page

Visual Studio  2008

• Download the pdf
• Go to the msdn page

Visual Studio 2005

• Download the pdf
• Go to the msdn page

Enjoy them !

I use Subsonic 3.0.0.4 with ActiveRecord and ASP.NET 3.5 SP1 webforms.

For this example, we are creating a blog post list and that the DAL is created (the data class we use is “DAL.BlogPost”).

The DAL.BlogPost object has three properties we need : CreatedOn, Subject and Body.

First step : prepare your data manager class

namespace MyBlog.BLL
{
   public class PostManager
   {
     // ...
   }
}

(keep in mind the namespace and the class for the nexts steps)

In this class, two methods are required,

The first returns the total number of items

public int GetPostCount()
{
  return DAL.BlogPost.All().Count(x => x.IsDeleted != true);
}

The second one returns the items contained in a defined range (start index and then nomber of elements), so this method needs to know where to start and how many items to get.

public PagedList<DAL.BlogPost> GetLastestPosts(int startRowIndex, int maximumRows)
{
   if (startRowIndex != 0)
   {
     startRowIndex =(startRowIndex/maximumRows);
   }

    IOrderedQueryable<DAL.BlogPost> yourQuery = DAL.BlogPost.All().OrderByDescending(x => x.CreatedOn);
    return new PagedList<DAL.BlogPost>(yourQuery, startRowIndex, maximumRows);
}

One important part to remember when using Subsonic is

if (startRowIndex != 0)
{
   startRowIndex = startRowIndex / maximumRows;
}

This conversion is necessary because subsonic and the ObjectDataSource doesn’t share the same opinion about the paging method.
Subsonic says

“I want the third page containing five elements”

ObjectDataSource says

“I want the five elements following the third element”

So the conversion is mandatory if you want a correct paging.

Second step : create the aspx page.

Declare an ObjectDataSource:

<asp:ObjectDataSource runat="server" ID="postsDataSource"
 TypeName="Example.BLL.PostManager"
 SelectMethod="GetLastestPosts"
 EnablePaging="true"
 SelectCountMethod="GetPostCount" >
 </asp:ObjectDataSource>

Note the TypeName attribute : the value is the namespace + the class name of our datamanager class.
We set the EnablePaging attribute to true and we specify the SelectCountMethod and the SelectMethod.

We don’t need any parameters for the paging, by default the MaximumRowsParameterName and StartRowIndexParameterName are set to “maximumRows” and “startRowIndex”.
If we want other parameters names in our datamanager class, we can define them in the ObjectDataSource with these two parameters.

Add an asp ListView element

<asp:ListView runat="server" ID="postsListview"
     DataSourceID="postsDataSource">
 <LayoutTemplate>
    <asp:PlaceHolder ID="itemPlaceHolder"
         runat="server" />
 </LayoutTemplate>
 <ItemTemplate>
    <h2><%# Eval("CreatedOn","{0:d}")%> :
     <%# Eval("Subject") %></h2>
    <br />
    <p>
     <%# Eval("Body") %>
    </p>
    <hr />
 </ItemTemplate>
</asp:ListView>

Set the DataSourceID attribute to the ObjectDataSource ID parameter.

Define a LayoutTemplate and an ItemTemplate with the elements we want to display.

Then add an asp datapager control in the LayoutTemplate

<LayoutTemplate>

  <asp:DataPager ID="postsDataPager" runat="server"
       PageSize="3">
    <Fields>
      <asp:NextPreviousPagerField ButtonType="Link"
           FirstPageText="<<" PreviousPageText="<"
           ShowNextPageButton="false"
           ShowFirstPageButton="true" />
      <asp:NumericPagerField PreviousPageText="..."
           NextPageText="..." ButtonCount="10" />
      <asp:NextPreviousPagerField ButtonType="Link"
           LastPageText=">>" NextPageText=">"
           ShowPreviousPageButton="false"
           ShowLastPageButton="true" />
     </Fields>
   </asp:DataPager>

   <asp:PlaceHolder ID="itemPlaceHolder" runat="server" />
 </LayoutTemplate>

Here is the result :

Remark about the data access method

It’s possible to avoid the start index value conversion !

Check the PagedList first constructor code (code is available on the subsonic git repository)

public PagedList(IQueryable<T> source, int index, int pageSize)
{
   int total = source.Count();
   TotalCount = total;
   TotalPages = total / pageSize;

   if(total % pageSize > 0)
     TotalPages++;

   PageSize = pageSize;
   PageIndex = index;
   AddRange(source.Skip(index * pageSize).Take(pageSize).ToList());
}

As you can see, Subsonic use the Skip and the Take methods from Linq

So, you can modify the GetLastestPosts method to return a strongly typed List in place of the PagedList:

public List<DAL.BlogPost> GetLastestPosts(int startRowIndex, int maximumRows)
{
   return DAL.BlogPost.All().
          Skip(startRowIndex).
          Take(maximumRows).
          OrderByDescending(x => x.CreatedOn).
          ToList<DAL.BlogPost>();
}

With this method, no more conversion needed

I’ve already test the  express edition when it was in beta phase, but it’s not the same …

So, let’s install it !

I install it on a Fujitsu Siemens laptop with 4 GB Ram and a Intel Core 2 Duo processor (2,53 GHz) running  Windows 7 64 bit Ultimate edition.

Launch the auto run program

Loading screen

Click Next

Read and accept the license terms

Choose your installation mode : Full installation (takes more than 6 GB) or Custom installation

I choose Custom

Select the features you want :

(notice that “Microsoft SharePoint Developer Tools” are integrated)

I just don’t want Dotfuscator community to be installed, so I uncheck  it

I keep the rest because I want to test some features

Click Install

Installation running :

After less than 10 minutes, the installation asked me to restart my computer:

I click “Restart Now”

When restarting, a loading form is showing

Then the setup continue

After about 45 minutes, the setup is finished

You can choose to install the documentation, but I choose to click on the “Finish” button.

The installation windows appears :

I Click Exit

Visual Studio 2010 is now installed

The installation takes me about one hour, and no problem occurred.

Now I can launch the product

I choose my default environment settings (I used to choose Visual C# Development settings so I pick this one).

I Click on “Start Visual Studio”

First time loading form

Visual studio is up and running

Help and documentation are on the start page:

A What’s new section is available on the start page :

• Visual Studio 2010 Overview
• What’s new in .NET Framework 4
• What’s new in Visual C#

Some other links are available :

• Creating application with Visual Studio
• Extending Visual Studio
• Community and Learning Resources

Some resources for Windows, Web, Cloud, Office,SharePoint and Data development are accessible too.

Next step : migration of a Visual studio 2008 solution !

You can use it to improve you ASP.NET Themes or your CSS files for all your web projects.

If you have many css files linked to a page, you can group them in a single file with CSS Mixer.

You can also minify CSS files to save the bandwith.

To use it, open a folder containing CSS files,

choose an action (simple combine, or combine and minify) then click Save as …

Download the last version of CSS Mixer on codeplex.

I hope you’ll find it usefull. please give me feedback on it

public static void CopyRowToAnOther(DataRow row, DataRow anOtherRow)
        {

            if (row == null || row.Table == null
                || anOtherRow == null || anOtherRow.Table == null)
            {
                return;
            }

            foreach (DataColumn colunm in row.Table.Columns)
            {
                if (anOtherRow.Table.Columns.Contains(colunm.ColumnName)
                && !row.IsNull(colunm.ColumnName)
                && colunm.DataType == anOtherRow.Table.Columns[colunm.ColumnName].DataType)
                {
                    anOtherRow[colunm.ColumnName] = row[colunm.ColumnName];
                }
            }
        }

The case :

You have an application with a CSS layout, and a few themes.
There is just a little change between the different themes, by example you change only the color scheme.

A solution to do that is to repeat all CSS files in all your themes, and change the color part.
The problem with that solution is that if you change one common style in one of your themes, you’ll have to repeat the change in all themes. This is a bad idea, it leads to chaos !

Then how can you do to avoid the code repetition ?

My solution:

1.) Create a Common Theme.

In the Common theme, you define CCS files with a default color scheme (just in case)

.testclass
{
border:solid 1px #DDDDDD;
background-color:#DDDDAA;
font-size:xx-large;
}

2.) Create an other Theme (let say “Green”)

In the Green theme, you define CCS files with only the color information

.testclass
{
background-color:#00FF00;
}

2b.) Create an other Theme (let say “Blue”)

In the Green theme, you define CCS files with only the color information

.testclass
{
background-color:#0000FF;
}

Your Theme structure has to look like this :

3.) Create a default page (Default.aspx)

And set the class of a div to “testclass” (define above)

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="ThemTests._Default"
%>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
 <title>Test with themes</title>
</head>
<body>
 <form id="form1" runat="server">
 <div>
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Praesent ut tellus eget turpis semper adipiscing sit amet id odio. Nunc vitae imperdiet tellus. Aenean quis orci metus, vitae placerat leo. Pellentesque luctus, lectus sit amet lacinia tincidunt, mi nibh sagittis nisl, vitae mollis eros nisi sit amet sem. Nunc dictum massa turpis. Etiam nisi mauris, consectetur et tempus id, pharetra in turpis. Nullam pretium ultricies nulla nec gravida. Sed porttitor metus nisl, ac condimentum nunc. Integer id feugiat orci. Maecenas ut lacinia purus. Mauris egestas mattis accumsan. Nunc in justo massa, quis egestas orci. Ut tincidunt, ligula sit amet tempor pharetra, magna mauris gravida mi, sed semper magna justo at velit. Donec vulputate fringilla lacus non sollicitudin. Morbi nulla nibh, pellentesque sed bibendum cursus, malesuada ut nisi.
 </div>
 </form>
</body>
</html>

4.) Edit the Web.Config file

Go to the “Pages” section, set the styleSheetTheme attribute to “Common” and the theme attribute to “Green”

<pages styleSheetTheme="Common" theme="Green">

Now launch your web application, the result has to be like this :

See in firebug :

Explanation :

This works because of the styleSheetTheme and theme attributes.

In fact, ASP.NET applies the styleSheetTheme defined theme first, then applies the page defined styles and at least applies the theme defined theme.

With this technique you can get rid of a few headaches.

If you just want to change the backcolor or things like that, you can spare some time by using only the ItemTemplate and applying a diffenrent style depending of the index (use of the Container.DataItemIndex property).

example : let’s say that your listview generate a <table> and each ItemTemplate generate a row of this table, just do :

<ItemTemplate>
  <tr class='<%# Container.DataItemIndex % 2 == 0 ? “normal” : “alternating” %>'>
    <td>blah blah</td>
  </tr>
</ItemTemplate>

that’s all you need !