Bluegenegeek

In this blog post I will talk about how to use ASP.NET Charting controls( which Microsoft announced last year) in a ASP.NET MVC application.

If you want to read more about ASP.NET Charting Controls here is a link to Scott Gu's Blog Post : http://weblogs.asp.net/scottgu/archive/2008/11/24/new-asp-net-charting-control-lt-asp-chart-runat-quot-server-quot-gt.aspx.

I will be using Streaming Chart Images as FileResult from MVC controller article on Code Project by Nic Roshe, to read more about the article here is a linkhttp://www.codeproject.com/KB/aspnet/MvcChartControlFileResult.aspx?msg=2959619.

Lets get started, create a new ASP.NET MVC application and add Reference toSystem.Web.DataVisualization. Add a Class to your project called ChartResult(Name can be anything I am just reusing the name used by Nic Roshe in the codeproject article). This ChartResultClass should derive from a FileResult Class. This Class would map and Image to a known MIME type. Further more since this class extends from FileResult Class System.Web.Mvc we get to override aWriteFile method which takes in a HttpResponseBase object. The WriteFile method can then be used to create a Output memory stream.

Here is how the Class would look like -

Please note using the ChartResult and FileResult Classes, the ASP.NET Charting Control will render as a Image file on your MVC View. Now lets see how this ChartResult can be used to render a ASP.NET Charting graph as a Image.

Lets look at how the View Page would look like -

There are two possibilities to render the image, we could create a ViewPage in MVC which just renders the Image or just use an <img> tag and specify its source to be the Action Method on the Controller.

The Home/BarChart and Home/PieChart are two MVC views which are just used for rendering purpose. If you feel that its a waste to create a view just to render an image you are right :). Hence the third line in the above snippet shows how the image tags src attribute can be used to render the image. We give the src attribute an Action Method which returns a FileResult.

Now here is how the Controller Code would look like,(please note this code need not be in a controller for sake of easy demo purposes I am putting it in a controller.)

Here is how a BarChart can be  constructed.

Here is how a PieChart can be constructed -

Here is how a LineChart can be constructed -

When you run the application you can see the two hyperlinks and an image being rendered on the Home Page

Here is a BarCart

 he

Here is a PieChart -

Hope this helps,

Cheers,

Venkata

I had to come up with a random and unbiased way of shuffling a list of items.

The first thing that came up to my mind is to sort using a simple for loop which iterates through the list of objects and calls the random function, something like this -

Then I read this post by Jeff Atwood - http://www.codinghorror.com/blog/2007/12/shuffling.htmlwhere he says the best way to do a random unbiased shuffling is to do a sort by a Random Number in .NET world a NewGuid().

Interesting, so I started to write a little sample to prove  that shuffling using a random sort indeed works. Here is an example snippet.

Notice at Line number 11 I call a .OrderBy(il=> Guid.NewGuid()).. Man it works like a champ. Here are some test results.

Iteration 1 :

3
2
9
6
1
0
8
7
4
5

Iteration 2 :

9
6
5
7
4
2
8
1
0
3

Hope this helps.

Cheers,

Venkata

Some time back I blogged about building my own blog, well I started building it in my spare time. As I mentioned previously, I am using ASP.NET MVC2 and .NET 4 as my platform.

To start with today, I would walk through how to build a simple contact me page by using ASP.NET MVC2's Model Validation Techniques.

First let us put the View Page together -

Below is the content section of my View which takes in a ContactMe as a Model

Here is the Header -

And here is the View Page - Notice the Html.EnableClientValidation() in Line Number about which I will be talking in depth below.

Notice the New TextBoxFor , TextAreaFor , ValidationMessageFor - Html Helper methods which are introduced in ASP.NET MVC2 and can take in LINQ Lamda Syntax(which I Love :), I will write a follow up post soon on these methods soon).

So the view is pretty straight forward which takes in a Model and Displays a simple Insert Form.

To get Client Side Validation in ASP.NET MVC2 to work all we have to do is drop in references to MicrosoftMVCValidation.js and MicrosoftAjax.js (which ship with the default project template for MVC2) and call Html.EnableClientValidation(). That's it from a View Point of view.

And from a Model point of view here's how we define validation rules. For this example I am going to be using Entity Framework, so the ORM generates my classes for me. I am going to use something called "buddy classes". Here a more about using buddy classes in Detail.

 Using Data Annotations with Entity Framework Classes -

After letting EF generate the classes, we write a partial class for the generated class, here is a snippet of how the partial class would look like -

Notice above, ContactMe is the class generated by Entity Framework and ContactMeValidator is our buddy class which holds the validation rules. All we are saying above is letting the framework know that if it encounters a Class named ContactMe then its MetaData information is in a Class Named ContactMeValidator.

Here's what a buddy class with validation logic would look like -

That is essentially it. We defined the validation rules in a buddy class which extends to hold the meta data information of classes generated by Entity Framework.

Here is a screen shot of how the webpage would look like

I will upload a code sample of this example soon.

Hope this helps,

Cheers,

Venkata