How can i use response.redirect from inside a function defined in Class file in c# 3.0

Question

I have a simple function GetPageName(String PageFileName, String LangCode) defined inside a class file. I call this function from default.aspx.cs file, In this function I am not able to use Response.Redirect("Error.aspx") to show user that error has been generated.

Below is example of Code

public static string GetPageName(String PageFileName, String LangCode)
{
     String sLangCode = Request("Language");
     String pgName = null;
     if ( sLangCode.Length > 6)
     {
        Reponse.Redirect("Error.aspx?msg=Invalid Input");
     }
     else
     {
         try
         {            
             String strSql = "SELECT* FROM Table";

             Dataset ds = Dataprovider.Connect_SQL(strSql);

         }
         catch( Exception ex)
         {
            response.redirect("Error.aspx?msg="+ex.Message);
         }
     }
     return pgName;
}

I have may function defined in Business and Datalayer where i want to trap the error and redirect user to the Error page.

Answer 1

HttpContext.Current.Response.Redirect("error.aspx");

to use it your assembly should reference System.Web.

Answer 2

For a start, in one place you're trying to use:

response.redirect(...);

which wouldn't work anyway - C# is case-sensitive.

But the bigger problem is that normally Response.Redirect uses the Page.Response property to get at the relevant HttpResponse. That isn't available when you're not in a page, of course.

Options:

• Use HttpContext.Current.Response to get at the response for the current response for the executing thread

• Pass it into the method as a parameter:

  // Note: parameter names changed to follow .NET conventions
  public static string GetPageName(String pageFileName, String langCode,
                                   HttpResponse response)
  {
      ...
      response.Redirect(...);
  }
  

(EDIT: As noted in comments, you also have a SQL Injection vulnerability. Please use parameterized SQL. Likewise showing exception messages directly to users can be a security vulnerability in itself...)