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EditorFor and Interfaces Pt1 – Display

This is a two part piece on working with Interfaces in MVC via the Html.EditorFor helper.

The first part – “Display” just covers one of those things I tried on the off chance, and was rather surprised that it worked right out of the box.

In the second part I’ll have a look at the next step of the process – binding these interfaces back to their models.

For reference, I’m working with MVC4, in VS 2012 For Web. I think this will also work in MVC3 at least.

Background

For a slightly messy user interface I’m working on, I wanted to be able to have a Model that holds a list of classes that implement an interface.

There is a possibility that all the classes might not be the same, and I was concerned that I was going to end up with a messy switch statement in my View that called the right Partial depending on which class I found in the list, and that this switch might need to be maintained on an on-going basis.

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DevExpress ASPxTreeList – Single node selection via client side JavaScript.

Using the DevExpress ASPxTreeList control recently I came across the problem of how to only allow one node checkbox to be selected at once.

There are examples on the DevExpress support site of implementing this using server side code and postbacks, however this isn’t so desirable, as incurring a postback for every time a node is clicked is fairly expensive.

I had a look into how to implement this using the ASPxClientTreeList functionality available to deselect nodes when other nodes are selected. The solution I worked out works reasonably well, with one caveat which is covered at the end.

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Determining the state of modifier keys when hooking keyboard input

As part of a utility I was writing recently I wanted to hook keyboard input. In particular I was interested in global hooks (ie input to any program, not just mine), and I needed to handle complex key inputs, for example Ctrl-Alt-G, i.e. keys plus modifiers. The usual way to do this is to use SetWindowsHookEx.

Looking around I quickly found a class over on CodeProject here. The globalKeyboardHook class deals with the hooking, allows you to specify which keys you are interested in and disregards the rest. The events are raised using the delegate type KeyEventHandler. KeyEventHandler uses KeyEventArgs and has easily referenced properties for each of the modifier keys. So far so good.

However I found that the instance of KeyEventArgs I was receiving in my event handler never had the modifier properties set to true. Looking at the code for the class I couldn’t see anything there that would set the properties in the call back function for SetWindowsHookEx.

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