For the last five months I've been working on a hobby project called Mangosteen Nation which is a website for XanGo distributors. I really wanted to use this project to look at some of the new things in ASP.NET and C# such as LINQ and it's been a great experience.

So here is a tip for efficiently grabbing data using LINQ in C# 3.0.

The way LINQ works from what I can tell is that lets say you write a query to get a user object from the database but then you want to access the comments for that user.

MangoData db = new MangoData();
Mangosteen.aspnet_Membership user  =  db.aspnet_Memberships.First(p=>p.UserId == UserId);
List commentsFromUser = user.Comments.ToList();

This will actually issue two queries to the database although it maintains the same connection. The reason is because it will only return the user object but none of the associated content in other tables. This is good for efficency as we don't need to see the other stuff in the other tables associated to the user but when we need to access that information, it will automatically make another query to the database. If you're not careful, you could end up with a lot of queries to the database that you're not aware of.

What you really want is for just one query to be executed so what we want is that when it returns the user object, it's filled with the comments for the user as well. But there  other associations and those shouldn't be returned. So how do we handle this? We use the DataLoadOptions.

If we modify our code with the new System.Data.Linq.DataLoadOptions settings, we'll get the following

MangoData db = new MangoData();

DataLoadOptions dlo = new DataLoadOptions();
dlo.LoadWith(p=>p.Comments);
db.LoadOptions = dlo;

Mangosteen.aspnet_Membership user  =  db.aspnet_Memberships.First(p=>p.UserId == UserId);
List commentsFromUser = user.Comments.ToList();

The data load options are declaring that whenever an aspnet_Membership object is loaded that the comments should also be loaded as well. Then you can attach that to the database object of your choosing to have those settings applied.

Last night I was creating a code generator using Code Smith that would create C# functions for every database function in a schema but I needed a SQL statement that would get me the definition of the function. It wasn't obvious how to retrieve the parameters and the return type for the already existing functions that were in the database. At first I thought I would be able to find a column in the database that had the DDL and parse it out for the values I needed but no such column existed.

So here is what I discovered. When a database function is being added, PostgreSQL parses out the database function parameters, return type, namespace, name of the function  and body and inserts them into some tables and columns. When the parse of the parameters is done, the parameter names are placed in one column surrounded on the ends by brackets and the parameter types are placed in another column. When the parameter types are stored, they are stored as their numerical representations instead of the names like "integer" and "numeric". Below is a list of some of the fairly commonly used types and their numbers.

    * 1043 char varying
    * 21 smallint
    * 1114 timestamp
    * 23 integer
    * 1700 numeric
    * 20 bigint
    * 25 text
    * 1082 date
    * 16 bool
    * 869 inet
    * 2279 trigger
    * 1790 set of refcursor

If you want to look at a list of all of the functions for a schema, the following SQL query will return the data needed. This SQL query was mainly derived from looking at EMS.

SELECT p.proname AS name, p.oid, p.proargtypes AS args, ds.description , p.prorettype AS rettype,
 p.proretset, p.probin, p.proisstrict AS strict, p.prosrc AS body, l.lanname AS lang,
 u.usename, p.prosecdef, p.provolatile, p.proisagg, n.nspname, proargnames, p.proargmodes, p.proallargtypes
FROM pg_proc p
LEFT OUTER JOIN pg_description ds ON ds.objoid = p.oid
INNER JOIN pg_namespace n ON p.pronamespace = n.oid
INNER JOIN pg_language l ON l.oid = p.prolang
LEFT OUTER JOIN pg_user u ON u.usesysid = p.proowner
WHERE n.nspname = 'public'
ORDER BY p.proname, n.nspname

"nspname" is the schema name that the functions will be pulled from. The parameters list that has the integer type definitions will be in the "args" column and the parameter names will be in the "proargnames" column. The "body" column contains the body of the function.

I will try to post the Code Smith template that I created for generating the C# classes soon.

I'm not an expert in using CSS but I can get around for the most part but the other day I needed to hide a section of a document with some Javascript and CSS. My problem was that when I'd use the property

visibility: hidden;

The content that was inside the hidden div tag would disappear but would still take up space on the screen. So then I found the CSS 2 collapse tag for use with tables.

visibility: collapse;

But the problem with this is that it's not supported in IE6 and that it also requires using tables. The nice thing about the collapse property is that it hides the content inside the tag but also causes the space that the content used to take up to disappear.

But to get around this and have a tag hide it's contents and not take up space on a page, use


display: none;

To show the tag again, use


display: inline; or display:block;

I find this to be amazing. I never realized that IIS worked like how Thomas Deml describes but I'm going to be making sure my web applications are optimized tonight probably for this.

    IIS will read the default document list and check file for file if the document exists in the physical directory of your site or vdir. IIS executes the document as soon as it finds the first match. You can imagine that this is pretty expensive. In the above case, supposing default.htm is the only default document that exists in your sites root directory,  IIS would check five times until it finds default.htm. And this happens for every request!

I've been using the Firefox developer tools called Aardvark Firefox extension for the last six months while doing HTML coding and I've found it extremely useful for analyzing a page I've created of the pages of other developers.

It sounds like IE may have created another tool that might be more useful to HTML and CSS coders though for their browser which I'm very excited about. It's called the Internet Explorer Developer Toolbar and it's in it's third beta. It's still in beta and it's not stable yet so it probably shouldn't be installed for production use but it's something to be aware of.


    The Internet Explorer Developer Toolbar provides several features for exploring and understanding Web pages. These features enable you to:


        * Explore and modify the document object model (DOM) of a Web page.
        * Locate and select specific elements on a Web page through a variety of techniques.
        * Selectively disable Internet Explorer settings.
        * View HTML object class names, ID's, and details such as link paths, tab index values, and access keys.
        * Outline tables, table cells, images, or selected tags.
        * Validate HTML, CSS, WAI, and RSS Web feed links.
        * Display image dimensions, file sizes, path information, and alternate (ALT) text.
        * Immediately resize the browser window to a new resolution.
        * Selectively clear the browser cache and saved cookies. Choose from all objects or those associated with a given domain.
        * Choose direct links to W3C specification references, the Internet Explorer team weblog (blog), and other resources.
        * Display a fully featured design ruler to help accurately align and measure objects on your pages.
        * Find the style rules used to set specific style values on an element.
        * View the formatted and syntax colored source of HTML and CSS.


    The Developer Toolbar can be pinned to the Internet Explorer browser window or floated separately.

    This Beta 3 version of the toolbar contains functionality and stability enhancements over previous versions, including:

        * Style Tracer: Right mouse click on a style value for an element and select Style Tracer to find the style rule that is effecting that value.
        * CSS Selector Matches: View a report of all style rules set and how many times they are used on the current page.
        * View Source: View the formatted and syntax colored source of the original page, currently rendered page, element or element with the styles that are effecting it.

I’m back to working on ASP.NET web applications again. Specifically I’ve been working with the ASP.NET 2.0 membership tools using a SQL Server 2005 database and so I’ve managed to build a list of pretty useful links and bits of knowledge that are handy to have when doing this.

Setting up a remote database for membership

By default, just quickly creating the ASP.NET application with the login controls on the website will cause the ASP.NET server to attempt to generate a database in the App_Data directory but I wanted to have the membership tables that ASP.NET will create be located on my database server with in my main database. This was a little bit trickier and there are a lot of different sites out there that propose ways of doing this but none of them seemed to work.

The simplest way I found was from the Discountasp.net forums. I am using Discountasp.net but when I run web application on my localhost and just connect to the Discountasp.net server, it works so I suspect this should work for all instances where you just need a simple remote membership database.

How to configure the ASP.NET 2.0 Membership/Roles Provider to use SQL 2000 or SQL 2005?

The information in this article applies to:


• ASP.NET 2.0


• MS SQL 2000


• MS SQL 2005

SUMMARY

This article describes how to configure the ASP.NET 2.0 Membership/Roles provider to use SQL 2000 or SQL 2005.

DETAILS

The following steps create the full Application Services database schema on our SQL Server database.

Open the command prompt on your local computer, and navigate to: C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727
Execute the command: aspnet_regsql.exe -S [DB Server Name] -U [DB login] -P [Password] -A all -d [Database name]

Currently, there is no management interface to manage the membership database besides using Visual Web Developer or creating your own application using the membership provider class.
Below is an example of how to configure Visual Web Developer to manage the membership database.

Create a web application in Visual Web Developer or Visual Studio 2005.


Open the web.config.


The default membership provider uses a connection string called "LocalSqlServer".

Therefore, replace:

<connectionStrings/>
with
<connectionStrings>
<remove name="LocalSqlServer" 
/>
< add name="LocalSqlServer" connectionString="Data Source=&lt;

DB_Server>;Integrated Security=false;

Initial Catalog=<

DB_Name>;

User ID=<

DB_User>;Password=<DB_password>" providerName="System.Data.SqlClient" />
</connectionStrings>

Save and close the web.config.


Go to Website menu, and run the ASP.NET Configuration tool. This will open the Web Site Administration tool.


In the Web Site Administration tool, go to the Security tab.


Click on "Select authentication type".


Select "From the internet". Click the Done button.


Create your admin roles and users.


Then create access rules.
Create a rule that applies to the "Anonymous users" with "Deny" permissions.
Create another rule that applies to the admin role you created with "Allow" permissions.

Your application is now ready to use the membership provider, and you can begin creating your login forms.

User logged in checked programmatically

You’ll need to check this a lot. Actually, it might be better to write your own methods to encapsulate this check but the easiest and fastest way to check if a user is logged in is to use the code.

The variable _loginPanel is a panel that contains the login form. If they’re logged in, it shouldn’t show up.

if (User.Identity.IsAuthenticated)
          _loginPanel.Visible = false;
      else
          _loginPanel.Visible = true;

Get the UserID of the user

There is going to come a point where you’ll need to access the UserID and it’s better to use the UserID when referring to the user than to use the UserName because the UserID column is the primary key by default in the database that the membership tools generate and so searching is going to be faster.

MembershipUser newUser = Membership.GetUser(User.Identity.Name);      
Response.Write("User key " + newUser.ProviderUserKey.ToString());

In order for this code to work though, the user must be logged in so you need to check to make sure the user is logged in before using this code otherwise you’ll receive an error.

Adding events after a user is created

When using the Create User control, there is an event on the CreateUserWizard called CreatedUser that fires after the new user has been saved to the database. This is handy if you need to add anything extra to the database after the user was generated.

  protected void Page_Load(object sender, EventArgs e)
  {              
      CreateUserWizard1.CreatedUser += _newUserCreated;
  }

  protected void _newUserCreated(object sender, EventArgs e)
  {      
      CreateUserWizard userWizard = (CreateUserWizard)sender;

      MembershipUser newUser = Membership.GetUser(userWizard.UserName);
      Response.Write("User key" + newUser.ProviderUserKey.ToString());
  }

Maintain scroll position when the user is created (On postback)

There are a couple of ways to do this. If you’re familiar with the AJAX libraries (formerly ATLAS) from Microsoft, it’s pretty easy to add an update panel so that only the User Creation control updates asynchronously but if you want a really fast way, adding the line

MaintainScrollPositionOnPostback="true"

to the top line of your aspx page is probably the fastest method for doing this. So my code looks like this.
<%@ Page Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" Title="Untitled Page" MaintainScrollPositionOnPostback="true" %>

Redirect after a user is created

One of the problems with the Create User control is that there are so many properties that all seem like they do the same thing. If you need to redirect the user to a members only page once they’ve registered, it’s pretty easy but the user must be authenticated which doesn’t happen when the CreateUserWizard.CreatedUser event is fired. But what happens is that a little lable replaces the original signup textboxes now alerting the user that they have successfully registered and there is a continue button. When the user presses this button, it then redirects them. I’m also assuming that clicking the button also signs the user into the site as well. So you need to set the CreateUserWizard property ContinueDestinationPageUrl to the page you want the user to be redirected to after they signup.

I’ve written quite a few encryption classes over the last month for File Phantom and I wrote this one while doing some testing that I thought was pretty simple to use if you need to do a quick encryption in C# using the Rijndael method. It takes a password that’s basically going to become the encryption key, creates the encryption key from the password and then creates the encrypted file and the last parameter sets whether the file that is being encrypted should become the encrypted file. If so, I replace the original and delete the newly created encrypted file. This last step might not be the most efficient but it seems safer than actually deleting one of the copies entirely and leaving the other in memory.

Feel free to use this code wherever you want.

The part of the code where I assemble the key I got from here.

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Security.Cryptography;
using System.Timers;


namespace FileEncrypterC
{
  /// <summary>
  /// This class is used to encrypt files.
  /// </summary>
  public class EncryptFileTools
  {
  
      /// <summary>
      /// Encrypts a file. Takes time.
      /// </summary>
      /// <param name="password">The password key. This is what determines the encryption method used.</param>
      /// <param name="_path">Path of the file that is to be encrypted.</param>
      /// <param name="_outputFile">Path of the encrypted file.</param>
      public static void Encrypt(String password, String _path, String _outputFile, bool _saveToSameLocationAsPath)
      {
          // This code came from another guide online. 
          {
              if (password.Length > 8)
                  password = password.Substring(0, 8);
              else if (password.Length < 8)
              {
                  int add = 8 - password.Length;
                  for (int i = 0; i < add; i++)
                      password = password + i;
              }
          }

          UnicodeEncoding UE = new UnicodeEncoding();
          byte[] key = UE.GetBytes(password);

          FileStream fsCrypt = new FileStream(_outputFile, FileMode.Create);


          RijndaelManaged RMCrypto = new RijndaelManaged();
          CryptoStream cs = new CryptoStream(fsCrypt, RMCrypto.CreateEncryptor(key, key), CryptoStreamMode.Write);

          FileStream fsIn = new FileStream(_path, FileMode.OpenOrCreate);
          int data;
          while ((data = fsIn.ReadByte()) != -1)
              cs.WriteByte((byte)data);

          fsIn.Close();
          cs.Close();          
          fsCrypt.Close();
          // The GC will collect the old objects faster
          cs = null;
          fsIn = null;
          //fsCrypt = null;

          // Now that the encrypted file is created, we'll replace the original file file with the output file
          // and delete the old file.
          if (_saveToSameLocationAsPath)
          {
              File.Replace(_outputFile, _path, _outputFile + ".backup");
              File.Delete(_outputFile + ".backup");
          }
      }
      /// <summary>
      /// Decrypt a file and save it to an outputed file.
      /// </summary>
      /// <param name="password">Password key</param>
      /// <param name="_path">File that's already encrypted.</param>
      /// <param name="_outputFilePath">File that results from decryption</param>
      public static void Decrypt(String password, String _path, String _tempOutputFilePath, bool _saveToSameLocationAsPath)
      {
          if (password.Length > 8)
              password = password.Substring(0, 8);
          else if (password.Length < 8)
          {
              int add = 8 - password.Length;
              for (int i = 0; i < add; i++)
                  password = password + i;
          }
          UnicodeEncoding UE = new UnicodeEncoding();
          byte[] key = UE.GetBytes(password);

          // Filestream of the new file that will be decrypted.
          FileStream fsCrypt = new FileStream(_tempOutputFilePath, FileMode.Create);

          RijndaelManaged RMCrypto = new RijndaelManaged();
          CryptoStream cs = new CryptoStream(fsCrypt, RMCrypto.CreateDecryptor(key, key), CryptoStreamMode.Write);

        
          // FileStream of the file that is currently encrypted.
          FileStream fsIn = new FileStream(_path, FileMode.OpenOrCreate);
          int data;
          while ((data = fsIn.ReadByte()) != -1)
              cs.WriteByte((byte)data);

          cs.Close();
          fsIn.Close();                     
          fsCrypt.Close();
          // The GC will collect the old objects faster
          cs = null;
          fsIn = null;
          fsCrypt = null;

          // Now that the encrypted file is created, we'll replace the original file file with the output file
          // and delete the old file.
          if (_saveToSameLocationAsPath)
          {
              File.Replace(_tempOutputFilePath, _path, _tempOutputFilePath + ".backup");
              File.Delete(_tempOutputFilePath + ".backup");
          }
      }
  }

  /// <summary>
  /// My little program to encrypt and decrypt a file using the

 // Rijndael RijndaelManaged class in the .NET System.Security.Cryptography library
  /// </summary>
  public class Program
  {
      static void Main(string[] args)
      {
        
        
          String _path = @"C:\Documents and Settings\Paul Mendoza\My Documents\TOOL.mp3";
          String _outputPathForDecrypedFile = @"C:\Folder.jpg";
          String _encodedFilePath = @"C:\newFolder.jpg";

          Console.WriteLine("Press any key to encrypt the file: " + _outputPathForDecrypedFile);
          Console.ReadKey();
        
          EncryptFileTools.Encrypt("paulmendoza", _outputPathForDecrypedFile, _encodedFilePath, true);
        
          Console.WriteLine("File encrypted.");
          Console.WriteLine(Environment.NewLine + "Press a key to decrypt: " + _outputPathForDecrypedFile);
          Console.ReadKey();
        

          EncryptFileTools.Decrypt("paulmendoza", _outputPathForDecrypedFile, _encodedFilePath, true);

          Console.WriteLine("File decrypted...." + Environment.NewLine);

                    
      }
  }

}