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ASP.NET MVC Basics: How to create a HtmlHelper

 ASP.NET MVC Basics: How to create a HtmlHelper Hello! And welcome to another tutorial on refactorthis.net.  This is the first tutorial in a series on ASP.NET MVC development.  This first installment will cover how to create an HtmlHelper.   What is ASP.NET MVC? I apologize if I'm stating the obvious, however, this is a tutorial on the basics so I'm approaching the tutorial with the assumption that the reader has no knowledge of ASP.NET, MVC, or ASP.NET MVC.  I'm sure you noticed that I made three references to the technology.  That's because ASP.NET MVC is more than one technology.  First we have ASP.NET, which is a server side web development technology created by Microsoft that utilizes the .NET framework.  Simply put, ASP.NET allows you to write dynamic web pages in .NET language of your choice (C#, VB.NET, etc..).  ASP.NET is an open source technology and it can be developed using the .NET framework or the Mono runtime.  You can find all sorts of wonderful information at http://www.asp.net/ . ASP.NET comes in two "flavors".  ASP.NET WebForms which is the original flavor, and ASP.NET MVC.  ASP.NET MVC is made up of two concepts.  First and foremost there is the MVC design pattern.  The MVC or Model-View-Controller design pattern was introduced by Trygve Reenskaug in the 1970's.  The design pattern has also be explained by Martin Fowler in his wonderful book on design patterns called Patterns of Enterprise Application Architecture . The idea behind the MVC pattern is that you have data that you wish to display (Model), you have a presentation layer in which you wish to display your Model (View), and you have a class that handles the interaction between the View and the Model (controller).  The MVC design pattern is an excellent example of a design with proper separation of concerns.  Applications that implement the MVC design pattern are generally loosely coupled, and easy to test (unit testing).  In ASP.NET MVC, the View is a web page, the model can be any class that holds data that you want to display in the View, and a controller class. Now that I've explained ASP.NET and MVC, I'll now explain ASP.NET MVC.  You see, not only is ASP.NET MVC an implementation of the Model-View-Controller design pattern, it's also a framework built by Microsoft to support the implementation of the MVC design pattern.  You will see as you begin working with MVC that the framework is a large part of what makes ASP.NET MVC what it is.  You could implement ASP.NET MVC without the framwork, however, I don't recommend it.  The framework will create controller's for you, create Views that are bound to a strongly typed model of your choice, and much more.  Using the ASP.NET MVC framework, you can create a basic CRUD web application in a very short amount of time. I hope that this gives you a nice overview of the ASP.NET MVC framework and design pattern. HtmlHelper: What they are and how to create them I'll explain HtmlHelpers by taking you through implementing one..  We'll start by firing up Visual Studio and create a new ASP.NET MVC 4 project (note: I'm using VS 2012, however, if you have an earlier version installed, simply choose whichever ASP.NET MVC version that you have available to you.  If you don't have any ASP.NET MVC templates, you can use the Web platform installer to install ASP.NET MVC on your system.       The next dialog allows you to choose which type of ASP.NET MVC application that you'd like to create.  We will pick an Internet Application, with the Razor View engine and a unit testing project as shown below.     Now click OK and your project will be created for you.  The ASP.NET MVC Framework will create a lot of boiler plate code behind the scenes.  This includes "Forms based Authentication" in the web.config file as well as an AccountController which is a controller to handle authentication to the site.  There is also a default controller called HomeController. We are going to create an html helper that creates an HTML table.  This is merely an example and is not particularly useful, however, it will show you how to create and use an HTML Helper.  An HTML helper is nothing more than an extension method which returns a string of HTML.  Here is the official definition of an extension method from MSDN: Extension methods enable you to "add" methods to existing types without creating a new derived type, recompiling, or otherwise modifying the original type. Extension methods are a special kind of static method, but they are called as if they were instance methods on the extended type. For client code written in C# and Visual Basic, there is no apparent difference between calling an extension method and the methods that are actually defined in a type. Creating the HtmlHelper  Create a folder called "Helpers" in your solution.  In the folder, create a static class called TableExtensions.cs .  The class will look like this: TableExtensions.cs using System; using System.Text; using System.Web.Mvc; namespace HtmlHelpers.Helpers { public static class TableExtensions { public static MvcHtmlString Table(this HtmlHelper helper, string id, string name, int rows, int columns) { if (string.IsNullOrEmpty(id)) throw new ArgumentNullException("id"); if(string.IsNullOrEmpty("name")) throw new ArgumentNullException("name"); if (rows <= 0) throw new IndexOutOfRangeException(); if (columns <= 0) throw new IndexOutOfRangeException(); StringBuilder tableBuilder = new StringBuilder(); tableBuilder.Append(string.Format("<table id=\"{0}\" name=\"{1}\">", id, name)); for (int rowCounter = 0; rowCounter < rows; rowCounter++) { tableBuilder.Append("<tr>"); for (int columnCounter = 0; columnCounter < columns; columnCounter++) { tableBuilder.Append("<td>"); tableBuilder.Append(rowCounter.ToString()); tableBuilder.Append("</td>"); } tableBuilder.Append("</tr>"); } tableBuilder.Append("</table>"); return new MvcHtmlString(tableBuilder.ToString()); } } } As you can see, we've created a static class and a static method. The the first method parameter is  this HtmlHelper helperThis is where the magic happens. This allows us to use the method from the View like all other HTML helpers.The other methods specify the number of rows and columns that should be built in the HTML table.Here is an example of how to use the helper: @using HtmlHelpers.Helpers; @{ ViewBag.Title = "Index"; } <h2>Index</h2> @Html.Table("myTable", "myTableName", 4, 4)The output looks like this: And there you have it folks.  I hope you enjoyed this tutorial.  If you have any questions please don't hesitate to leave a comment. Thanks for reading.


How to configure mono 2.10, .NET 4.0 and ASP.NET MVC to run on an Ubuntu Apache web server.

The challenge... As per my previous post [post title here], I wanted to configure mono on my recently installed Ubuntu machine.  Specifically, I wanted to be able to use the latest .NET functionality as well as ASP.NET MVC integration with Apache.  In this post, I plan to provide the steps and resources in which I took to accomplish my goals. Let's start with the Ubuntu machine.... The Ubuntu desktop specifications The machine in which I've installed Ubuntu is an OLD machine that I had laying around the house.  My Android has more horsepower than this old Dell, however, Ubuntu 10.4 seems to operate at a perfectly acceptable capacity.  I plan to "refresh" my Linux skills and look for spare RAM to add to this machine before I upgrade to Ubuntu 12.04.  The recommended minimum requirements for Ubuntu 12.04 are as follows; [For installing] The minimum memory requirement for Ubuntu 12.04 is 384 MB of memory for Ubuntu Desktop. Note that some of your system's memory may be unavailable due to being used by the graphics card. If your computer has only the minimum amount of memory, the installation process will take longer than normal; however, it will complete successfully, and the system will perform adequately once installed. [For upgrading] While the minimum memory requirement for 32bit is 384 MB, a minimum of 512 MB is needed for the 64bit installation. On systems with only the bare minimum amount of memory, it is also strongly recommended to use the "Install Ubuntu" option as it uses less memory than the full live session. Ubuntu Desktop System Requirements for 12.04 LTS What's with all the aPtitude? As much as I love aptitude, I'm quite annoyed by the time it takes for source repositories to list packages as "stable".  I understand that this has nothing to do with the package manager itself and that the Ubuntu version carries more of the blame, even so, I wanted to simply apt-get install mono-complete, I would be stuck with mono 2.4.  Since I wanted to use   some newer functionality, I had some planning to do.  The overall process went a little something like this; Find a bash script that compiles all of the mono packages that I needed to get the job done. Execute the script and watch some T.V while I waited for the massive compile to complete. Move the Apache mono module configuration into the "available modules" folder to enable mod-mono under Apache. I needed to create an Apache virtual host configuration file with the mod-mono specific settings that are required. I had to prepare my file system to serve my ASP.NET applications (c:\inetpub\wwwroot\ for all you Windows natives). I needed to provide a simple solution to publish ASP.NET applications from Visual Studio on my Windows 7 machine to my Ubuntu web server. Finally I needed to restart apache2, publish a web application and test the fruits of my labor. BASHing mono into shape As I stated before, I wasn't going to apt-get install my way into the wonderful world of mono with all of the specific details that my target installation required.  Luckily, I found this post http://www.integratedwebsystems.com/2011/02/mono-2-10-install-script-for-ubuntu-fedora/  in which someone created a BASH script that would download all of the specific packages and compile the sources to produce the exact environment that I was after.  I'm sure  if I had used a modern PC it wouldn't have taken so long, never the less, the compilation was quite a time consuming task indeed!  The script was authored very well in that if there was an error detected, the script would break execution to make it easier for you to find what went wrong.  Fortunately, my compilation completed without a hitch!   Enabling mod_mono in Apache The BASH script had installed created the mod_mono.conf configuration file but I had to find it and copy it to the enabled modules directory so that Apache would recognize it. Here is the command that I executed from a terminal to copy the file to the proper location sudo cp mod_mono.conf /etc/apache2/mods-enabled Of course I had to find the configuration file before I could copy it sudo find -name mod_mono.conf With the configuration file in place, I restarted Apache to make sure all was well sudo service apache2 restart The service restarted successfully so I felt OK with what had been done so far. Creating the mono virtual host configuration file There is a webiste that will require you to fill in some input fields and click a button to generate this file the virtual host configuration with mono specific settings.  I merely had to modify one line of the file. The website is http://go-mono.com/config-mod-mono/ I simply used localhost as my server name and it generated the physical path of /srv/www/localhost. I used nano to edit the file and I modified the MonoDirectory line to point to the correct path of my mono_server4 binary's path which I was able to search and find to be /opt/mono-2.10/bin . Creating wwwroot, or /svr/www ... It was now time to prepare my file system to setup a home for my site hosting.  This basically involved creating some folders, setting permissions and creating an alias link or two. Create the directories sudo mkdir /srv/www sudo mkdir /srv/www/localhost Assign a root group to the folder sudo chown root:www-data /srv/www/localhost -R Change the directory attributes sudo chmod 775 /srv/www/localhost -R I then moved the virtual host site generated file to the appropriate path mv ~/Desktop/localhost.conf /etc/apache2/sites-available I then created a symbol link so I could refer to the vhost configuration file with leading zeros (Apache loads the configurations alphabetically). sudo ln -s ../sites-available/localhost.conf "000-localhost.conf" I restarted Apache, fired up firefox, browsed http://localhost and that's all it took...  I hope you enjoyed reading this article and I hope this helps someone configure ASP.NET MVC under Apache on Ubuntu using mono.  Until next time.. ~/Buddy James   kick it on DotNetKicks.com  


The mono project. The state of .NET on non Microsoft platforms.

Ubuntu too I've recently decided that I wanted to install linux on an older PC in my home.  Many moons ago, before most linux distributions could auto detect and configure your hardware, I had cut my teeth on Debian.  I've had a soft spot ever since for the aptitude package manager.  Naturally I wanted to use a distro that was based on Debian so I went with Ubuntu.  The Ubuntu CD that I have is dated (version 8.04) so I did some research and decided to upgrade to version 10.04.  I fired up a terminal and executed 'sudo do-release-upgrade -d' to apply an upgrade to my system. Watching LED dry The upgrade was a pretty long process, and I found myself watching the terminal window as all of the packages were added, upgraded, and removed.  As I watched, I noticed that quite to my surprise, there were many packages that relied on mono assemblies.  As a .NET consultant, of course this had sparked my curiosity.  I've followed the mono project, from a distance, for a while now but I knew that there was a following, however, I had no idea that mono had made it's way into the heart of the packages that make up an Ubuntu installation.   The current state of things I've decided to take a 1,000 feet view of the current state of the mono project.  As stated by the official website; The easiest way to describe what Mono currently supports is:Everything in .NET 4.0 except WPF, EntityFramework and WF, limited WCF.   That's quite a lot of functionality!  I had no idea that there had been so much work done on the project.  I can write a .NET 4.0 application, an ASP.NET MVC 2 web application and host it on a linux based Apache server.  Well at least that's what the website has told me. Perhaps I'll try to accomplish just that and write about how smooth the whole process actually is. Here are some links for those who are interested. The official mono homepage http://www.mono-project.com/Main_Page The mono project compatability http://www.mono-project.com/Compatibility The mono migration analyzer MoMA http://www.mono-project.com/MoMA Design apps for your iPhone or iPad using monoTouch http://xamarin.com/monotouch Design apps for your android device using mono for android http://xamarin.com/monoforandroid I hope you found something of interest.  Until next time.. ~/Buddy James   kick it on DotNetKicks.com  


About the author

My name is Buddy James.  I'm a Microsoft Certified Solutions Developer from the Nashville, TN area.  I'm a Software Engineer, an author, a blogger (http://www.refactorthis.net), a mentor, a thought leader, a technologist, a data scientist, and a husband.  I enjoy working with design patterns, data mining, c#, WPF, Silverlight, WinRT, XAML, ASP.NET, python, CouchDB, RavenDB, Hadoop, Android(MonoDroid), iOS (MonoTouch), and Machine Learning. I love technology and I love to develop software, collect data, analyze the data, and learn from the data.  When I'm not coding,  I'm determined to make a difference in the world by using data and machine learning techniques. (follow me at @budbjames).  

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