Well we’ve arrived at the last part of our series on ASP.NET MVC. In this post we’ll be looking at Views, ViewData, and HTML Helpers. We’ll be discussing how to call Views from Controllers and how to use HTML Helpers to create your markup.

Views In A Nutshell

Suppose we receive the following request; http://yourdomain.com/Task/Show/23. The request would map to the following controller.

   1: public class TaskController : Controller 

   2: { 

   3:     public ActionResult Show() 

   4:     { 

   5:         return View(); 

   6:     } 

   7: } 

Hi

A while ago Shahar wrote an article about whether WPF Data Binding is Thread safe. Shahar’s findings were that Even if you change a property from a different thread the PropertyChanged event will be called on the UI Thread making Binding Thread Safe.

I have created a Window with 2 TextBlocks, one of them is binded to a Dependency Property and the other is binded to a regular property:

The Window:

   1: <StackPanel>

   2:     <TextBlock Text="{Binding DpTxt}" Width="100" Margin="5"></TextBlock>

   3:     <TextBlock Text="{Binding Txt}" Width="100" Margin="5"></TextBlock>

   4:     <Button Content="Change Text" Margin="5" Click="Button_Click"></Button>

   5: </StackPanel>

Hi

Where do you locate your convertors? do you put them in the Window.Resources section? or in the UserControl they are being used for? Neither of these options is good. You should put it in the App.Xaml file and here is why:

Lets look at the following example:

Here is our Window:

   1: <Window x:Class="ConvertorLocation.Window1"

   2:     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

   3:     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

   4:         xmlns:my="clr-namespace:ConvertorLocation"

   5:     Title="Window1" Height="300" Width="300">

   6:     <Grid>

   7:         <ItemsControl ItemsSource="{Binding}">

   8:             <ItemsControl.ItemTemplate>

   9:                 <DataTemplate>

  10:                     <my:UserControl1></my:UserControl1>

  11:                 </DataTemplate>

  12:             </ItemsControl.ItemTemplate>

  13:         </ItemsControl>

  14:     </Grid>    

  15: </Window>

Hey all, Check out the top right corner of your screen! Dev102 has hit 1000 RSS readers!!!
Thank you all for reading
The Dev102 team.

Hi

While working on a complex UI application in WPF I noticed that because I was using DataTemplates both the Xaml and the Code Behind got very messy, that is because if you need to implement some events in the code behind you basically “mix” code from the template and code from the Window, plus you cannot access the elements in the template from the code behind.

Let’s look at the following example:

Hi.

As the Headline says, I will show you how to make a Drag and Drop / Move Content control. for this example I will use a canvas and an Image. But you can easily make it more generic by using a Content Control instead of the image.

It is actually very simple, let’s start with the Xaml Code.

   1: <Canvas Grid.Row="1" Grid.Column="1" Grid.RowSpan="2" HorizontalAlignment="Stretch" 

   2:         VerticalAlignment="Stretch" x:Name="ImageHolder" >

   3:     <Image Canvas.Left="0" MouseWheel="Img_MouseWheel" MouseMove="Img_MouseMove" 

   4:            MouseDown="Img_MouseDown" MouseUp="Img_MouseUp" Panel.ZIndex="0" 

   5:            Cursor="Hand" Canvas.Top="0" Height="150" Width="150" Source="sketch.jpg" 

   6:            x:Name="Img">

   7:     </Image>

   8: </Canvas>

Implementing Drag and Move

to implement the drag and move we will need to use the following events:

• MouseDown
• MouseMove
• MouseUp

MouseDown event

So far we have looked at the requirements for our fictional application and the data structure that goes with that, the application’s Model using a repository pattern , and URL Routing to provide friendlier URLs.

What we have covered so far really is just supporting code. In this post we’ll look the first of two parts that really hold our application together, the Controller. In the next post we’ll cover the View and how it ties into the Controller.

Lately I was working on an application that had to display a large amount of objects on screen and allow filtering. I have learned that scrolling large collections was not so simple in WPF, and I definitely did not see the problems coming.

Memory Consumption

Here is an example of a simple WPF application which randomly creates 50000 Classes of type DATA in a list and displays them in an Item control:

We have been looking at all the parts that make a sample ASP.Net MVC application. Previously we have discussed the database schema of our application as well as implementation of the Repository Pattern with filters on that schema. If you haven’t been following this series of posts you might want to read parts 1 and 2 before continuing. Url Routing has become a very common these days. In fact, at least among the websites I visit, it has become more common than not routing urls.

Here we are talking about filtering list items again :). I got two comment suggesting the use of yield return.

James Curran said:

Don’t build a new list if you don’t have to.

private static IEnumerable EvenSlicker_FilterPositiveItems(IEnumerable t)

{

foreach(int n in t)

if (n > 0)

yield return n;

}

The advantage is if you try using the method this this:

foreach(int n in FilterPositiveItems(myList) {…}

Your way is O(2N) while mine is O(N)