Application model entity localisation in Asp.net MVC

If you are an Asp.net MVC developer and live in non English speaking country, then you've faced the challenge of application localisation. Although frameworks these days support localisation it's usually not a straightforward process. Especially when it comes to web applications. There's always a dilemma how to implement localisation and how to choose request locale. Should it follow browser language settings or user preference? Either way there's an underlying base foundation that can be used to implement each.

This post is not about localisation in general but rather just about application model classes and their property names localisation when presented in Asp.net MVC views by means of Html.LabelFor() extension methods. There already is a class DisplayNameAttribute but it lacks capabilities we need.

This blog post is related to .net framework 3.5 and older because there's a new attribute provided by the .net framework 4 and newer. It's called DisplayAttribute which has even more capabilities than those implemented below.

jQuery UI slider extension that enhances range capabilities

I'm going to provide you with the code that makes it possible to set bounds to range slider handles (minimum and maximum) and some more sugar along with it.

I needed to create a range slider that is a bit smarter than the one provided by jQuery UI library that only allows to set minimum and maximum values for the whole slider, but I needed to set a few things more. I had to provide a range slider that would allow users to select time range between midnight and midday the next day (36 hours all together). These were my requirements:

• Lower handle can only move to midnight the next day (so it can move between 00:00 and 1d 00:00) - this simply means that time range must start today
• Selected range must be at least 1 hour wide
• Selected range can't be wider than 24 hours all together

These were my requirements and although I like jQuery UI plugins/widgets and even though it comes with a slider it doesn't work as expected. I could of course put it all in my slide handler, but tha wouldn't be reusable and it would also not allow me to do some additional things I implemented along. Want to know which ones?

BLToolkit MapResultSet builder

or How I refactored my seemingly identical methods with generic type parameters

As I've written in the past I'm using BLToolkit lightweight ORM on one of my projects. But some parts of it seem very silly actually and I can't really see why did they decide to do certain parts the way that they did. One of them being the configuration for multiple result sets. You know those where you write TSQL query that returns more than one result. BLToolkit has this nice DbManager mapping method called ExecuteResultSet() that takes an array of MapResultSet objects. And these you have to prepare yourself first so mapper will actually populate your object lists. Their example looks like this (just the relevant code):

   1:  List<Parent> parents = new List<Parent>();

   2:  MapResultSet[] sets = new MapResultSet[3];

   3:   

   4:  sets[0] = new MapResultSet(typeof(Parent), parents);

   5:  sets[1] = new MapResultSet(typeof(Child));

   6:  sets[2] = new MapResultSet(typeof(Grandchild));

   7:  // and so on and so forth for each result set

   8:   

   9:  using (DbManager db = new DbManager())

  10:  {

  11:      db

  12:          .SetCommand(TestQuery)

  13:          .ExecuteResultSet(sets);

  14:  }

As you can see you have to create an array of MapResultSet objects of the correct size (using a magic value - and you know I don't like them) and then set an instance to each (again using magic values). Seems tedious? I thought so as well. Hence I've done it differently.

Cross browser headers with vertical rotated text

You've probably come across the problem of displaying these kind of tables:

• many columns
• header column at the top
• content cells display narrow data - flags (yes/no, true/false, y/n, on/off, finite states like yes/no/maybe etc.) or just icons that denote some sort of state as in feature list tables where each cell displays either a check-mark or nothing or green and empty cirles or similar...
• header cells contain much wider data than content cells - more words that take much valuable horizontal space

If you had to display these kind of tables you've probably been thinking how could you make header cells narrower but not clip their content so headers still make sense... The idea is to display header cells as tall cells with vertically displayed text so columns can stay narrow as their content cells need. This way our tables get horizontally usable and don't take much space. It's true that header row becomes higher (depending on the amount fo text that you'd like to display, but hey there's just one header row in the whole table.

Anyway. So if you did struggle with this and also wanted it to display approximately the same on all three major nowadays browsers than you did spend some time solving it. If you didn't but you think you may in the future, then just use the code I'll provide here and off you go.

Use CSS floats to flow data in columns rather than rows with jQuery .transpose() plugin

I know we have CSS3 multi-column layout that makes HTML content flow in columns dead simple but the problem is that only the most modern browsers (as of July 2011) support this CSS3 capability. As you might have guessed this means tough luck for Internet Explorer users. Microsoft decided that CSS3 column layout is not something developers or better web designers would need so IE still doesn't support it. Not even in version 9 that is.

Even though CSS3 multi-column support got supported recently we have been displaying data in pseudo columns for some time. We either displayed tables when we had tabular data or used CSS floats or CSS inline-blocks when displaying lists and we didn't want the list to be long and narrow which makes it hard to use. The nice thing about floating is that elements take as much horizontal space as they can inside container and when individual items are set a fixed width this means that they will display in column-like layout. The problem is though that floated items run in rows meaning that when you have alphabetic text (or numbers) list items they won't flow in columns as we're used to ie. in phonebooks. No. Items flow in rows. This makes these kind of lists hard to read and search through. But I have a solution for you. jQuery plugin that re-arranges your items into columns to improve their usability.

Removing route values from links/URLs in Asp.net MVC

I didn't really know how to properly title this post to make it easily searchable by those who bump into routing-related issue. Words like arbitrary, ambient, unwanted, unneeded, extra, unrelated etc route values popped into my mind, but I decided to title it as it is now.

One of the main pillars of Asp.net MVC is routing. Many applications can just use default route definition to cover all their scenarios but some applications require it to be a bit more complex. Look at this example:

   1:  routes.MapRoute(

   2:      "CustomerSpecific",

   3:      "Customers/{customerId}/{controller}/{action}/{id}"

   4:      new { controller = "Customers", action = "Index", id = UrlParameter.Optional },

   5:      new { customerId = @"\d+" }

   6:  );

   7:   

   8:  routes.MapRoute(

   9:      "Default",

  10:      "{controller}/{action}/{id}",

  11:      new { controller = "Home", action = "Index", id = UrlParameter.Optional }

  12:  );

Seems fine? Well it does and it works, but you will have problems when you'll be anywhere in http://www.domain.com/Customers/n/... and would like to also generate links to parts of your application that are covered by default route definition (second route). Let me show you why.

Improving Asp.net MVC maintainability and RESTful conformance

I've used Asp.net MVC for a few years now but this issue I've stumbled upon just a few days ago seems something everydayish and I wonder how come I've never bumped into it. It has to do with Asp.net MVC routing and action method selection. First of all think of default route definition that looks like this:

   1:  // default application route

   2:  routes.MapRoute(

   3:      "Default",

   4:      "{controller}/{action}/{id}",

   5:      new { controller = "Home", action = "Index", id = UrlParameter.Optional }

   6:  );

Mind that id route value is optional? Yes optional. So it should be perfectly feasible to have two action methods: one with the id parameter and one without it: public ActionResult Index() { ... } and public ActionResult Index(int id) { ... } But you've probably guessed it? This doesn't work out of the box. You'll get a runtime error stating that there are two matching action methods for the current request. A bit strange? I thought so as well. So let's try and accomplish just that!

jQuery animated "scroll into view" plugin (with additional ":scrollable" selector filter)

Sometimes our pages have to deal with long(er) unpaged lists of data. Long enough to fall off the viewable browser window estate. Actually you don't even have to deal with lists at all. Let me re-define the problem: when you have a scrollable element on your page (may be the very body of it) and you need to programmatically scroll to its out-scrolled child element, then this jQuery plugin is just for you. Now let's see when we have to do this and what could go wrong.

How to correctly use IHttpModule to handle Application_OnStart event

In one of my previous blog posts (Writing a custom IHttpModule that handles Application_OnStart event) I've been talking about using IHttpModule to also handle application start event which is a non-documented feature. Sure it works, but you may see some strange behaviour of duplicated (or even multiplicated) functionality being executed. You probably won't see this with your applications in development, because your local IIS isn't really heavy duty workhorse, but in production environment you may see this strange behaviour. Investigating it is even a bit more complicated because of the running application serving live traffic. Let me help you. So I will point you in the right direction and more importantly show you a solution that makes things work reliably even on a heavy load IIS.

Custom Asp.net MVC route class with catch-all segment anywhere in the URL

Asp.net MVC routing does a fine job with routes that have a finite number of segments. We define them with route URL pattern string. The default provided by the Asp.net MVC project template being {controller}/{action}/{id}. Most web applications can do everything using only this single route definition and many developers don't even think beyond this standard. But sometimes this single route just isn't enough or it's just not acceptable.

A real world example

Think of a web site you're building that has hierarchically organised categories. Like Amazon. We have books, music, electronics, etc. And every top category has sub categories. And so on and so forth. Using default route definition we would access a particular (sub)category simply by: www.domain.com/categories/index/647 That's fine, but it's definitely not human friendly. If we'd change our route URL definition to {controller}/{action}/{id}/{name} this would already be much friendlier: www.domain.com/categories/index/647/web-development That's something similar (not the same, because we're still using action names here) to what Stackoverflow does with it's questions.

But now think of this super human readable web address: www.domain.com/books/computer-internet/web-development/latest This one would display latest web development books. As we can see it defines categories in hierarchical order similar to breadcrumbs. All in human readable format. Doing this kind of routing isn't supported out of the box (because we have an action at the end), but I think we could do better. Let's try and create a route that supports this.

Generate enum from a database lookup table using T4

This is something rather common. You're building an application that uses database storage in the background. If your database isn't completely trivial and you're not fatally in love with magic values/numbers, then you probably also use lookup tables to gain referential integrity when it comes to certain types, codes and similar data. But to follow the DRY software development principle we want to use these values defined in database on upper layers as well without manually writing any additional code. Because as mentioned magic values are evil regardless of where they're used.