Changing C# on the fly (without stopping the debugger) in an ASP .NET vNext web application with Visual Studio 14 CTP3

The roslyn compiler found in Visual Studio 14 enables us, to adjust C# code during runtime, by compiling the new C# code in-memory. Now we can edit the UI part (HTML, CSS, JavaScript) of a single page app, including the backend C# ASP .NET Web Api service dynamically in runtime.

 

On of the things, that disrupts my workflow, when creating a single page app with AngularJS, backed by a web api C# service in Visual Studio 2013, is the fact that, when I find a bug in my C# code while testing the UI, I have to stop the debugger, adjust the web api C# code, re-compile, re-run and then recreating state in the web app before I can resume testing the UI.

This pain will go away, when using Visual Studio 14

 

Download and install Visual Studio 14 CTP 3 from http://msdn.microsoft.com/en-US/subscriptions/downloads/

Open Visual Studio, choose File > New > Project …

 

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Start the web application by pressing CTRL + F5 (so don’t start the debugger).

 

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Click on the Contact page in the browser:

You will see the text “Your contact page”.

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Now go to the Controllers\HomeController.cs

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Adjust the the C# code: ViewBag.Message = "Your contact page.";

to

ViewBag.Message = "My contact page.";

 

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Save the file and in the browser press F5, you might see a short delay, because the roslyn compiler is now dynamically compiling the code.

 

The C# code is changed without disrupting my workflow.

 

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