In an effort to start blogging more about the "helpful" items that I have encountered over the years this is one of my first "Quick Tips" related to improving the life of the developer. We all have had those times where we are tracking down a complex problem within an application and all along the way we have to spend endless time mousing over individual classes to find out what their values are when most commonly we just want to know about one or two key values. Well in this post, I'll show you a neat trick using the "DebuggerDisplay" attribute to help make this process easier.

The Code

To get us started I'm going to just dive into the code, consider the following super condensed code sample.

   1:  static void Main(string[] args)
   2:  {
   3:      var badSampleInstance = new BadSample()
   4:                              { Name = "John Smith",
   5:                                  Address = "123 Main Street",
   6:                                  Phone = "515-555-1212" };
   7:      var goodSampleInstance = new GoodSample()
   8:                              { Name = "John Smith",
   9:                                  Address = "123 Main Street",
  10:                                  Phone = "515-555-1212" };
  11:      Console.ReadLine();
  12:  }
  13:   
  14:  public class BadSample
  15:  {
  16:      public string Name { get; set; }
  17:      public string Address { get; set; }
  18:      public string Phone { get; set; }
  19:  }
  20:   
  21:  [DebuggerDisplay("{Name} ({Phone})")]
  22:  public class GoodSample
  23:  {
  24:      public string Name { get; set; }
  25:      public string Address { get; set; }
  26:      public string Phone { get; set; }
  27:  }

From here we can see a very simple set of code with two classes. If you notice I have added an attribute "DebuggerDisplay" to the top of the GoodSample class. The value used for the display contains a few substitutions "{Name}" and "{Phone}". What this does is update all of the display areas in the debugger, that would typically show the type name for the value which isn't helpful to show the formatted value we supplied. An example of this can be seen here.



So as you can see this can help to get a good glance into your custom objects, and reduce a lot of the "mouseover" action that is common while debugging.

I hope that this content was helpful.

In this article I will explain how to read or write connection strings in web.config file using asp.net.

I have one web application that contains many pages and each page contains relationship with database connection to get data from database and display it on page because of that I need to write database connections for each page to interact with database. Now the server name or credentials of database server has changed in that situation it will create problem because we need to modify the database connections of each page using asp.net.

To avoid this situation it would be better if we place connection string in one place and reuse it in every page wherever we need to connect to SQL Server. Web.config is the best place to store the connection strings in asp.net and it would be safer place to store the connection strings instead of writing connection strings in every web page.

Now we want to add connection string in web.config file for that first create new website using visual studio after that create new website open web.config file and search for “connectionStrings” and add new item in connectionStrings section

After open web.config file in application and add sample db connection in connectionStrings section like this

< connectionStrings>
< add name="yourconnectinstringName" connectionString="Data Source= DatabaseServerName; Integrated Security=true;Initial Catalog= YourDatabaseName; uid=YourUserName; Password=yourpassword; "
providerName="System.Data.SqlClient"/>
</ connectionStrings >

Example of declaring connectionStrings in web.config file like this

< connectionStrings>
< add name="dbconnection" connectionString="Data Source=Scott;Integrated Security=true;Initial Catalog=MySampleDB" providerName="System.Data.SqlClient"/>
</ connectionStrings >

Here to access my database server there is no need of username and password for that reason I didn’t enter username and password in connection string.

After add dbconnection in connectionString we need to write the some code in our codebehind file to get connection string from web.config file for that add following namespace in codebehind file and write the following code

using System.Configuration;

This namespace is used to get configuration section details from web.config file.

After add namespaces write the following code in code behind

C# code

using System;
using System.Data.SqlClient;
using System.Configuration;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
//Get connection string from web.config file
string strcon = ConfigurationManager.ConnectionStrings["dbconnection"].ConnectionString;
//create new sqlconnection and connection to database by using connection string from web.config file
SqlConnection con = new SqlConnection(strcon);
con.Open();
}
}

VB.NET

Imports System.Data.SqlClient
Imports System.Configuration
Partial Public Class _Default
Inherits System.Web.UI.Page
Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
'Get connection string from web.config file
Dim strcon As String =
ConfigurationManager.ConnectionStrings("dbconnection").ConnectionString
'create new sqlconnection and connection to database by using connection string from web.config file
Dim con As New SqlConnection(strcon)
con.Open()
End Sub
End Class

OK, finish.

You may receive the following error message while browsing an asp.net application

"Server Error in '/application name' Application
--------------------------------------------------------------------------------

Runtime Error
Description: An application error occurred on the server. The current custom error settings for this application prevent the details of the application error from being viewed remotely (for security reasons). It could, however, be viewed by browsers running on the local server machine.

Details: To enable the details of this specific error message to be viewable on remote machines, please create a tag within a "web.config" configuration file located in the root directory of the current web application. This tag should then have its "mode" attribute set to "Off". "

This error might occur due to two scenarios.

1. There is an error in the application's logic with the inputformat, Type etc., and you have set the Custom Error Mode in the web.config to "On" and not specified a default redirect error page.

2. The web.config file is not well formed or having invalid characters and the application is not able to pick up the settings from the same.

Solution

1. Set the custom error mode to "Off" to view the error. After rectifying it and before deployment, change it to "On" and specify a default error page, as follows:-

<customErrors defaultRedirect="ErrorPage.aspx" mode="On">
</customErrors>

such that your users will not be able to see the actual error and get your friendly error page where you can politely say "An error has occured! Sorry for the inconvenience ..." .

2. If the above solution is not working (i.e. even after setting the custom error mode to On, the same "Server Error" occurs, then the likely chance is that your web.config file is not well formed and has invalid characters etc.,

To resolve, it copy paste the contents of the file to a notepad, save it as an xml file and try to browse the xml file in the browser. If the xml file is unable to be rendered by the browser and throws error, then you can find the place where the tags are not well formed or invalid character(s) exist and rectify them.

Things worth noting is Web.config is case sensitive and even trailing / leading spaces can cause the above error.

This article applies to .NET - ASP.NET 1.0, 1.1 Versions. Hope it help

Sometime when you try to setup a application for your website on IIS7 you get following error when you load your website.



This happens when ASP.NET modules and handlers should be specified in the IIS and configuration sections in Integrated mode. This problem can be fixed using following workaround

1) Change application configuration: First way to fix this issue is to migrate the application configuration to work properly in Integrated mode. You can use “ AppCmd“ command to migrate the application configuration:

%windir%/system32/inetsrv/>Appcmd migrate config “<AppPath>

Where “ <AppPath>“ is the virtual path of the application, such as “Default Web Site/virtualapp1“.

2) Modify web.config: You have to manually move the customer entries in the <system.web>/<httpModules> and configuration to the <system.web>/<httpHandlers><system.webServer>/<handlers> and <system.webServer>/<modules> configuration sections, and either remove the <httpHandlers> and <httpModules> configuration OR add the following to your application’s or websites web.config:

<system.webServer>
<validation validateIntegratedModeConfiguration=”false”/>
</system.webServer>

3) Switch to Classic ASP.NET: Switch the website or application to an application pool that is configured to run in Classic ASP.NET mode. To move back to classic mode go to IIS7 Manager >> Select the site (which you want to switch) >> edit settings and you will get following screen



Press “ Select” button which will open a window “Select Application Pool” (check below image); Select “Classic .NET AppPool” from the drop-down and press OK.



Now try to Access your website/application.