ASP.NET MVC – Creating a DropDownList

I’ve been looking at the ASP.NET MVC framework for the past two weeks, and it has occurred to me that some of the simple things we may want to do when creating a web application may seem confusing to someone new to ASP.NET MVC – for example the task of creating a DropDownList control on a form. ASP.NET MVC provides a number of ‘HTML Helpers’ which we can easily use to construct the form items. ‘DropDownList’ is one of these HTML helpers we can use.

Let’s create a simple example form using some of these HTML helpers. To begin a form, we can use a helper, we just need to add this code to our View:


<% using (Html.BeginForm()){ %>

// Form data will go here

<% } %>

This creates the basic form code for us – no need to explicitly write any HTML code. Before adding the DropDownList control, we need to decide where we want to get the data which will bind to the list. We can either hard code the items, or use LINQ to SQL to grab them from a database at runtime.

Method 1 – Hardcoding the form items

With this approach, we just add the items to a list, and pass this list to ViewData, so we can access it from the View:


List items = new List();
items.Add(new SelectListItem
{
Text = "Apple",
Value = "1"
});
items.Add(new SelectListItem
{
Text = "Banana",
Value = "2",
Selected = true
});
items.Add(new SelectListItem
{
Text = "Orange",
Value = "3"
});

ViewData["DDLItems"] = items;
return ViewData;

Then, to actually display the DropDownList, we’d just need to add a single line to our View code, utilizing the DropDownList HTML helper:


<%= Html.DropDownList("DDLItems") %>

Method 2 – Using LINQ to SQL to get the data at runtime

We could also retrieve the list data from a database table at runtime using LINQ to SQL. In order for this approach to work, you will need to have generated LINQ to SQL classes for your database using the wizard in Visual Studio. Then we can easily write the code to retrieve the data:


// Get the list of supported languages (for example) from the DB
var db = new TransDBDataContext();
IEnumerable languages = db.trans_SupportedLanguages
.Select(c => new SelectListItem
{
Value = Convert.ToString(c.ID),
Text = c.Name.ToString()
});

ViewData["SupportedLanguages"] = languages;
return View();

Again, to display the DropDownList, we’d just need to add a single line of code to the View:


<%= Html.DropDownList("SupportedLanguages") %>

From the above, you can see how easy it is to render form items using the HTML helpers provided by ASP.NET MVC.

For a full list of the helpers, check out the MSDN documentation here.

Windows Phone 7 Development – First Impressions

Since my Christmas leave from work has begun, I’ve had some time to really look at Windows Phone 7 development over the last 2 days, and have gotten really excited about it all. I’ve been meaning to do this for ages (since WP7 was released actually), but have always either been too busy or suffered procrastination (thanks Zen Habits!).

Some positives:

  • Development Environment – I think Microsoft has done an excellent job on Visual Studio 2010, and the WP7 development tools plug in seamlessly. If you don’t already have Visual Studio 2010, Microsoft is offering a special Express Editon for Windows Phone.
  • Developer Resources – There are a huge amount of resources available on Microsoft’s App Hub (often called ‘MarketPlace’ – the equivalent of Apple’s ‘App Store’), ranging from tutorials, walkthroughs of some key concepts and full application code examples.
  • The Windows Phone Emulator – This is installed as part of the developer tools, and it really is state of the art. I haven’t purchased an actual device running WP7, but have been using the emulator to test my inital application effort. There are some obvious things that won’t work on the emulator, for example anything to do with the accellerometers (the emulator assumes it is lying on a flat surface), but it’s perfect for testing your inital Windows Phone 7 applications.
  • Familiarity – If you’ve ever developed using C# on the Windows platform, you already have a huge start in WP7 development.
  • Developer Subscription – The cost of a yearly developers subscription, a mere 99 Euro, can easily be covered with very little downloads of your applications (should you even be bothered about it).

The only ‘negative’ I’ve found so far is that I’ve had to purchase a (long overdue) brand new Dell running Windows 7 in order to create my development environment. My previous machine, running Windows XP, is not supported by the Windows Phone 7 development tools, which seems strange to me, since XP is not scheduled to be EOL’d until 2014. It seems to be another move by Microsoft to push people to move to Windows 7 or (shudder) Windows Vista.

Windows Phone 7 development is one of the three areas I want to become proficient with in the first half of 2011. I had initially focused on the iOS platform, but when I thought about it, it didn’t make much sense, since I’m already familiar with C# and didn’t feel I’d gain any real advantage by learning Objective C. Also, rumours began to circulate this week regarding Microsoft getting into bed with Nokia, so WP7 will surely gain more momentum in the first half of 2011.

My first application, (well under way!), will be a simple Twitter client. The reason I chose this is that it will encompass many of the key concepts I’ll need to learn, such as designing user interfaces for WP7, storing information locally on a WP7 device, and accessing external information via API’s. I plan to complete this over Christmas – screenshots to follow once it is.

Aside: If you’re interested in getting into developing on the Windows Phone 7 platform, check out Jeff Blankenburg’s 31 Days of Windows Phone, it’s the best introductory article series I’ve found so far.

What to learn next?

I’ve been a bit all over the place recently in terms of what to learn next. The main languages I’m proficient in at the moment are C#, and web programming languages like PHP. (Aside: If I hear one more person refer to HTML as a programming language I may get angry). The thing about the software industry is that something you spend a long time mastering may be obsolete in 5 years. If you’re not continuously learning, you can fall behind very fast.

Over the next 6 months to 1 year, I’ve decided to focus on certain technologies/areas in an effort to become someway proficient in them.

I’ve decided on:

  • C++ – The expert consensus is that this will not be replaced in the next 50 years.
  • Mobile Development – But I’m unsure of which platform. iOS development interests me as I own an iPhone, but it has the extra added learning curve of Objective C, of which I have little experience. I’m thinking Android or Windows Phone 7 (should it be accepted by the masses), since I’m familiar with both Java and C#.
  • ‘Newer’ Microsoft technologies such as Silverlight, WPF etc. from the last few years that I haven’t looked at.

I feel if I apply myself I can certainly become proficient in the above areas in less than a year. By ‘proficient’ I mean be able to develop applications from the ground up as I can do in C# at the moment, not ‘master’. I’m fully aware that languages like C++ take thousands of hours to learn and many years of hands on experience to fully master.

No doubt I’ll be posting here of my experiences learning each.

Retrieve settings from COM+ components via C#

Recently, I had a requirement to be able to retrieve settings information from a number of COM+ components running on a server, such as the Constructor String etc. The idea behind this was to give us a snapshot of a servers configuration, and also allow easy comparisons between different servers in the event of issues. This is tedious and time consuming to do manually, especially if you’ve got a large number of components within each COM+ application, so I resolved to write a small C# program to do this for me and write the data to a file.

COM+ provides an administration object model that exposes all of the functionality of the Component Services administrative tool, so by adding a reference to the necessary library, you can achieve anything you can do through the graphical administrative tool, programmatically. To get started, you’ll need to add a reference to the necessary library – ‘COM + 1.0 Admin Type Library’. This can be found under the ‘COM’ tab when you go to add a reference to your project in Visual Studio.

You’ll need to add the following import also:


using COMAdmin;

First, we’ll need to create an Object to store the catalog of COM+ components installed on the machine. Here’s the code to create this catalog, and also retrieve a list of all the COM+ applications it contains:


COMAdminCatalog catalog;
COMAdminCatalogCollection applications;

// Get the catalog
catalog = new COMAdminCatalog();

// Get the list of all COM+ applications contained within this catalog
applications = (COMAdminCatalogCollection)catalog.GetCollection("Applications");
applications.Populate();

Now we have an Object above, ‘applications’, which contains all the data regarding what COM+ applications are installed on this machine. To go a little deeper, and see which components each application contains, it’s just as easy:


foreach (COMAdminCatalogObject application in applications)
{
COMAdminCatalogCollection components;
components = (COMAdminCatalogCollection)
components = (COMAdminCatalogCollection)applications.GetCollection ("Components", Application.Key);
components.Populate();

foreach (COMAdminCatalogObject component in components)
{
Console.WriteLine("Component: " + component.Name);
}
}

The above code shows you how to get a list of COM+ applications and their components, but what about retrieving or setting the values of specific component settings like the Constructor String of a component?

Here’s how:


// Set the value of a constructor string
component.set_Value("ConstructorString", "127.0.0.1");
// Get the value of a constructor string
component.get_Value("ConstructorString"));

That’s a quick overview, I leave it as an exercise to the reader to explore the other functionality of the ‘COMAdmin’ library, but if you just need to retrieve values of settings from specific components, the above will get you started.

As per normal, MSDN has some great documentation here.

iPhone Application Development

I’m currently learning the application development process for the iPhone OS. A book that caught my eye recently while browsing Amazon was “Building iPhone Apps with HTML, CSS, and JavaScript: Making App Store Apps Without Objective-C or Cocoa” by Jonathan Stark. Since I don’t own a Mac currently, and don’t really feel I’d get any value from learning Objective-C, this sounded like the perfect place to start.

First off, I think the title is perhaps a little misleading. The author advocates building iPhone applications as web applications, rather than native iPhone OS applications. This has all the obvious advantages of any web application, (faster development cycles, real-time bug fixes etc.), but has a few unique advantages from the iPhone developers perspective. First off, you dont need to register (and pay!) to become an Apple developer. Secondly, your web application will not need to through Apple’s approval process as you will not need to submit it to the App Store in order to deploy it to your users.

Obviously, there are also some serious challenges to overcome if you make your application web based, with the main one being you will need to implement your own payment system if you wish to charge for your application.

The book contains many good tips for optimizing your web based application for the iPhone OS specifically. In Chapter 6, there’s also information on how to convert your web based application to a native iPhone app, using PhoneGap, although you do need a Mac to do this. Then your application will have to go through the Apple approval process in order to be made available on the App Store. It may be refused – but while you work on this and make any modifications necessary etc, your web based version is still available.

I’ve found this book a great starting point, now all I need to do is get the time to complete my app! I’ll be posting a release note here once I do, so stay tuned…

12 Steps to Better Code

The ‘Joel Test’ has been around a long time (Joel Spolsky originally wrote the article in 2000), but having only discovered Joel’s blog in the last year, and reading every article back this far, I think this particular post is amazing.

For those not familiar, the ‘Joel Test’ is Joel Spolsky’s 12 simple steps to better code and a better software development process. Lately, I’ve been trying to adhere to these steps in some personal projects, and some development projects I’m involved in at my day job.

Here are the questions to ask yourself when rating the software team you work in:

1. Do you use source control?
2. Can you make a build in one step?
3. Do you make daily builds?
4. Do you have a bug database?
5. Do you fix bugs before writing new code?
6. Do you have an up-to-date schedule?
7. Do you have a spec?
8. Do programmers have quiet working conditions?
9. Do you use the best tools money can buy?
10. Do you have testers?
11. Do new candidates write code during their interview?
12. Do you do hallway usability testing?

Read Joel’s full article here, I think it’s great!