SuperSKa Weblog : ASP.NET

LINQ to SQL Connectionstring in web.config

Stefan Kamphuis — Fri, 13 Mar 2009 04:38:00 GMT

For starters, there's probably dozens of places on the web already, with a solution for this very same issue, but here's mine anyway.

The issue is this: when creating a website in ASP.NET using LINQ to SQL, you've probably guessed it would be a good idea to put the connectionstring in web.config. Especially since there's a special section for them there.

However, when you create a LINQ to SQL Databaclasses (.dbml) file and drag your tables on it, it's automatically configured to use the database you dragged the tables from.

And it's pretty easy to solve too. First, we want to get the connectionstring out of the .dbml file. To do this, open the .dbml file in the designer and change it's data-properties to match this:

Then, create a new partial class for the generated DataContext class with only a default constructor in it. This default constructor will pass the connectionstring from web.config to the constructor if it's base class, and you're al set:

public partial class MyDataContext{
    public MyDataContext()
        : base(ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString,mappingSource)
    {
    }
}

This way, you can always regenerate your dataclasses without having to remember to change

use the right connectstring.

Have Fun!

ASP.NET: Leaping from Webforms to MVC - part 2

Stefan Kamphuis — Mon, 09 Mar 2009 08:56:43 GMT

Alright, some time has passed since my previous post on this matter. And I must say, I'm not getting more enthusiastic on ASP.NET MVC. Not that it's not good or anything, it just solves some problems I wasn't experiencing (more on that here). The main issue I'm running into is that my pages are somewhat dynamic. That means, based on several conditions, the form displays in one of several ways (for example: based on a property of an object a field displays as either a label or a textbox).

At this point I'm typing a whole lot of crappy code in my HTML within <% %> tags. It just feels soooo retro...

ASP.NET: Leaping from Webforms to MVC

Stefan Kamphuis — Mon, 02 Mar 2009 15:06:57 GMT

Ever since late 2007 (I think ) I've been reading quite a bit on the ASP.NET MVC framework. Even did some playing around here and there but never got to use it on a project. Until last week that is. I'm now working on a website that's built entirely on the ASP.NET MVC framework. And of course, working on a project things are just a tad different from playing around a bit.

So, what is it that makes working with the MVC Framework so much different from Webforms? Well, let's just put a small list here of some of the things I ran into. Needless to say that this is not a complete list, nor is it intended to be...

Where are the servercontrols?

Well, errrr, they're gone. You don't have them. You're writing good old HTML again yourself. Of course, the advantage here is that you gain a lot of control over the HTML of your website. But, of course, no Servercontrols means "no events". You even need to pull a trick to make a DropDownList autopostback (more on that here)...

Only one <Form> in a page?

Alright, an advantage of the MVC Framework. Every now and then I tend to run into this situation where I need some part of a page to submit to a different URL. In ASP.NET you need to use javascript to change the Action of the Form before it's submitted. Or at least, that's one approach of numerous you could choose from...

In ASP.NET MVC you can easily have different forms on a single page. Love that part.

More to come

... as I experience. I decided to post and update this one along the way.

Autopostback DropDownList with ASP.NET MVC

Stefan Kamphuis — Mon, 02 Mar 2009 01:44:00 GMT

Didn't you love the days back when you could just open up the properties tab for your DropDownList in ASP.NET and set the AutoPostBack Property to True? You could even write code in your codebehind class to handle the event properly. Cool, right?

But these are the days of the ASP.NET MVC framework, so everything's different now. Well, of course I'm being a bit sarcastic here and there are a lot of advantages too to the MVC Framework, but still it requires more work to achieve things-that-used-to-be-simple.

Anyway, back to the AutoPostBack of the DropDownList. First, of course, you need to have a DropDownList on your page:

<select id='dropDown' name='dropDown'>
  <option value="1" selected="selected">Option 1</option>
  <option value="2">Option 2</option>
</select>

Note that this control needs to be within your Form otherwise it's values will not be submitted of course...

When you have the control, you'll need to make it submit the Form it's in. I chose to do so with jQuery, but you could do it with plain javascript too:

<script type='text/javascript'\>

  $('#dropDown').change(function () {
    $(this).parents('form').submit();
  });

</script>

For those of you not fully up to speed with jQuery: this code finds the element named "dropDown" and adds a handler to the onChange event of it. The handler first finds the parent of the DropDownList with elementname "form", and submits it.

You could also change the action of the form here in the handler if that might be needed, for example to fire a specific controller action for the postback of the DropDownList.

Streaming images from aspx page

Stefan Kamphuis — Wed, 13 Aug 2008 08:42:18 GMT

I know, not a very advanced topic, but still one of those things you need every now and then. And when you need it, it's a good thing that the solution is all over the Internet. And now it's on my blog too .

Using a Handler for this would probably have been the more beautiful solution, but this one (with an aspx page) works fine too. Default.aspx only contains an asp:Image control. The Image control has it's source set to Image.aspx. Image.aspx, in turn, draws a blue rectangle with a red square in it (pretty neat, huh?) :

private Bitmap drawImage()
{
    //Create a bitmap
    Bitmap bmp = new Bitmap(100, 100);

    //Get the Graphics object from the bitmap (using it's Image base)
    Graphics g = Graphics.FromImage((System.Drawing.Image)bmp);

    //Color it blue
    g.FillRectangle(new Pen(Color.Blue).Brush, 0, 0, 100, 100);
    //Draw the red rectangle
    g.DrawRectangle(new Pen(Color.Red), new Rectangle(5, 5, 90, 90));

    //and we're done
    return bmp;
}

Then, in the Page_Load event, the image is streamed to the browser:

protected void Page_Load(object sender, EventArgs e)
{
    //Clear the responsestream, just to be sure.
    Response.Clear();
    //Set the Responsetype
    Response.ContentType = "image/jpeg";
    //Save the dynamicly generated bitmap to the OutpuStream
    drawImage().Save(Response.OutputStream, ImageFormat.Jpeg);

    //End we're done.
    Response.End();

}

It's as simple as that.

Download Solution - ImageStreamer.zip