Using a Stored Procedure in Entity Framework 4

If you have worked with LINQ and added stored procedures to it, it would seem obvious to be able to it the same way in Entity framework.

In LINQ all you had to do is to drag the stored procedure from your Server Explorer respective data connection on your model diagram.

In entity framework 4, there are few steps and they are different.

1. On your entity diagram in visual studio, right click and choose Update Model from database.

2. Add your stored procedure from the wizard. What it does, it adds the proc to your diagram. Its not visible in .Net code yet.
If you go to Model Browser > {EntityModel}.Store > Stored Procedures, it should be visible in there now

3. Right click, Add > Function Import. Complete this according to your requirement, name of the proc you want to see in .Net, which stored proc it maps to and what is the collection it returns etc.

After step 3 you can access access the proc using an instance of context.

For more visual representation of the steps, please visit WebLog of Ken Cox

Extracting tags from xhtml content

There are two ways of doing it. One is the dirty way, using Mid function in VB.Net or IndexOf string method but the more appropriate way would be to use regular expressions.

Following code will get you title using regular expression

Regex regex = new Regex("<title>(?<title>.*?)</title>", RegexOptions.IgnoreCase);
Match titleMatch = regex.Match(html);
string title = titleMatch.Groups["title"].Value;

Following code will get you meta tag My_Meta

Regex regex = new Regex("<META +NAME=\"(?<name>My_Meta*?)\" +CONTENT=\"(?<content>.*?)\" */?>", RegexOptions.IgnoreCase);

Match metaMatch = regex.Match(html);

title = metaMatch.Groups["content"].Value;

Saving objects using Entity framework

TableClass tableObject = new TableClass();
tableObject.property1 = "Hello";
tableObject.proeprty2 = "World";

// NOTE: make sure to use the same instance of entityContextObject which was used to populate the tableObject (e.g. updating back to database)
entityContextObject.AddToTableClass(tableObject);
entityContextObject.SaveChanges();

Accessing email settings from web.config

Rather than using appSettings, a section from webconfig is a better use for email settings which gives you typed properties in .Net code.

Link: http://dotnetslackers.com/Community/blogs/kaushalparik/archive/2008/09/06/accessing-web-config-file-smtp-mail-settings-programmatically.aspx

Deleting Rows in DataTable - .Net

A colleague asked me about deleting rows from DataTable. He was having an issue when removing the rows of the datatable because he was using method DataTable.Rows.Remove(index).

When you are looping through any collection using for each loop, you cannot modify the collection. In order to Delete the rows, the best way is to use the Delete method of the particular row(s) and once you are done with the loop, method accept changes of DataTable will remove the rows from DataTable. Code example is

' Loop though the table

For Each dr As DataRow In ds.Tables(0).Rows

If (dr("Name") = "ABC" Then

dr.Delete()

End If

Next

ds.Tables(0).AcceptChanges() ' this remains outside of the loop

Understanding Lamda Expression

Came across a very good article by Panopticon Central. He explains it very well the use with both syntax for VB Net and C#. Visit the following link for details

Link: http://www.panopticoncentral.net/archive/2006/12/08/18587.aspx