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I blogged not too long ago about some stuffs that I was pondering…

Finally found out how one can get the “Object of type ‘System.Decimal’ cannot be converted to type ‘System.Int32’” error.

Given this code:

using System;   
  using System.Data;   
  using System.Data.SqlClient;   
  using System.Collections.Generic;   
     
  namespace ConsoleApplication1   
  {   
      public class Foo   
      {  
          public int Id { get; set; }  
          public int Number { get; set; }  
      }  
    
      class Program  
      {  
          static void Main(string[] args)  
          {  
              var foos = new List<Foo>();  
              var fooType = typeof(Foo);  
    
              using (var cn = new SqlConnection(@"Server=.\SQLEXPRESS;Database=JimmyTest;Integrated Security=true"))  
              {  
                  using (var cmd = cn.CreateCommand())  
                  {  
                      cmd.CommandText = "SELECT * FROM dbo.[tablea] a INNER JOIN dbo.[tableb] b ON a.[BId] = b.[Id]";  
                      cmd.CommandType = CommandType.Text;  
    
                      cn.Open();  
    
                      using (var reader = cmd.ExecuteReader(CommandBehavior.CloseConnection))  
                      {  
                          var fieldCount = reader.FieldCount;  
    
                          while (reader.Read())  
                          {  
                              var foo = new Foo();  
    
                              for (var i = 0; i < fieldCount; i++)  
                              {  
                                  var property = fooType.GetProperty(reader.GetName(i));  
                                  if (property != null)  
                                  {  
                                      property.SetValue(foo, reader.GetValue(i), null);  
                                  }  
                              }  
                              foos.Add(foo);  
                          }  
                      }  
                  }  
              }  
    
              Console.ReadLine();  
          }  
      }  
  }

And this database:

USE master
GO

CREATE DATABASE JimmyTest
GO

USE JimmyTest
GO

CREATE TABLE tablea (Id int, BId int, Number int)
GO

CREATE TABLE tableb (Id int, Number decimal(10,2))
GO

INSERT INTO tablea VALUES(1, 1, 100)
INSERT INTO tablea VALUES(2, 2, 50)
GO

INSERT INTO tableb VALUES(1, 33.33)
INSERT INTO tableb VALUES(2, 15.23)
GO

Can you spot the bug?

Found it in the wild while troubleshooting one of my clients’ code.

Hint: Greed is one of the seven deadly sins.  It’s pure evil!

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*cheer*

All right, ladies and gentlemen.  I'm your host with the most, BuggyFixius.  *cheer and clappings*

Today we have an exciting web bug for you.  Let's see if you can... *altogether now* SPOT THE BUG!!

We have with us today, an ASP.NET website project *clappings*.  The project contain a helper class like so:

using System.Web;

public class WebHelper
{
    const string PARAM_USER_ID = "u";

    static HttpRequest request;

    static WebHelper()
    {
        request = HttpContext.Current.Request;
    }

    public static string GetUserId()
    {
        return getRequest(PARAM_USER_ID);
    }

    static string getRequest(string key)
    {
        string value = request[key];
        return string.IsNullOrEmpty(value) ? string.Empty : value;
    }
}

*Ooo, Aaaa and some gasps*

It also has a Default.aspx file containing a plain Label control

  <%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_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>Untitled Page</title>   
  </head>   
  <body>  
      <form id="form1" runat="server">  
      <div>  
          <asp:Label ID="Label1" runat="server" />  
      </div>  
      </form>  
  </body>  
  </html>

and the following Page Load event handler:

using System;   
using System.Web.UI.WebControls;   
     
public partial class _Default : System.Web.UI.Page    
{   
    protected void Page_Load(object sender, EventArgs e)   
    {   
        Label1.Text = WebHelper.GetUserId();   
    }  
}

*Some more Ooo, Aaaa and some more gasps*

Contestants... it's time to *altogether now* SPOT THE BUG!!

Hints: open Default.aspx in the browser 2 or more times given a different u querystring.  For example: http://localhost:34939/Default.aspx?u=3959 and then replace the url with http://localhost:34939/Default.aspx?u=4000.