Design Pattern Riddle #14

q. There once were two incompatible classes,
they were mismatched and unable to commune.
Then along came a extraordinary pattern,
that allowed them to sing the same tune.

a. Adapter

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Design Pattern Riddle #13

q. I'm all about creating families;
The kinds that have a common subject.
There is no need to provide specific details,
When using this conceptual mill project.

a. Abstract Factory

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Design Pattern Riddle #12

q. I flip through the Rolodex of objects;
You don't have to know how their made.
I give a way for each object to shine,
As they walk down the object parade.

a. Iterator

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Design Pattern Riddle #11

q. I'm in the business of procreation,
But I'm not the kind who likes to crow.
I gladly give power to those that inherit;
I'm the first to tell the object, "hello!"

a. Factory Method

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Design Pattern Riddle #10

q. I make a group of objects seem as one;
behind the scenes I resemble a deep rooted plant.
I contain a family of parents and children,
but no where in me can you find an aunt.

a. Composite

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Design Pattern Riddle #9

q. I let you take charge of the various implementations;
I am highly abstract, but generically planned.
A superclass can localize your common behavior,
but there is plenty of room for you to command.

a. Template Method

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jQuery Flexigrid Using C# 3.0 (.NET 3.5) & LINQ

When I developed my first ASP.NET MVC application, I was a little disappointed with my options for a rich grid. I initially used the grid that is part of the MVCContrib project, but it is pretty simple and there aren’t many features out of the box.

I was very pleased with the code of my MVC application, but the presentation was so 1990's. With all of this new technology I thought the presentation deserved something snappy. That is when I found Flexigrid.

As I mentioned in my last blog entry, I started to use jQuery. To my joy, Flexigrid is a jQuery plugin! Flexigrid uses jQuery to asynchronously populate the contents of the grid using either XML or JSON input.

The following is an example of what the grid looks like. It contains features to sort, page, search, move columns, resize, etc…



The User Interface portion was pretty straightforward to put together. You just need to define your columns, the data source, and some additional parameters (such as: search terms, size, etc…).

I wanted to use this opportunity to try out some new features of .NET 3.5, so I wanted to incorporate LINQ and JSON serialization.

To do this, I needed to setup some classes that the Flexigrid will recognize once serialized. Here is what I came up with.

   1: public class FlexigridViewData

   2: {

   3:     public int page;

   4:     public int total;

   5:     public List<FlexigridRow> rows = new List<FlexigridRow>();

   6: }

   7:  

   8: public class FlexigridRow

   9: {

  10:     public long id;

  11:     public List<string> cell;

  12: }

Now is the part where the fun begins. I had already retrieved the content I needed from the Middle Tier. I use LINQ to query the generic list to obtain the correct page subset and then use a helper extension method to serialize the contents to JSON.

   1: public void Page_Load()

   2: {

   3:     Response.Clear();

   4:     Response.ContentType = "text/x-json";

   5:     Response.Write(GetPagedContent());

   6:     Response.Flush();

   7:     Response.End();

   8: }

   9:  

  10: private string GetPagedContent()

  11: {

  12:     var pageIndex = Convert.ToInt32(Request.Params["page"]);

  13:     var itemsPerPage = Convert.ToInt32(Request.Params["rp"]);

  14:     var sortName = Request.Params["sortname"];

  15:     var sortOrder = Request.Params["sortorder"];

  16:     var query = Request.Params["query"];

  17:  

  18:     IEnumerable<Contact> pagedContacts;

  19:     if (string.IsNullOrEmpty(query))

  20:     {

  21:         pagedContacts = sortOrder.Equals("asc") ?

  22:             Contacts.OrderBy(contact => contact.GetPropertyValue<IComparable>(sortName)) :

  23:             Contacts.OrderByDescending(contact => contact.GetPropertyValue<IComparable>(sortName));                

  24:     }

  25:     else

  26:     {

  27:         Func<Contact, bool> whereClause = (contact => contact.GetPropertyValue<string>(sortName).Contains(query));

  28:         pagedContacts = sortOrder.Equals("asc", StringComparison.CurrentCultureIgnoreCase) ?

  29:             Contacts.Where(whereClause).OrderByDescending(contact => contact.GetPropertyValue<IComparable>(sortName)) :

  30:             Contacts.Where(whereClause).OrderBy(contact => contact.GetPropertyValue<IComparable>(sortName));

  31:     }

  32:     int count = pagedContacts.Count();

  33:     pagedContacts = pagedContacts.Skip((pageIndex - 1) * itemsPerPage).Take(itemsPerPage);

  34:  

  35:     const string imageLinkFormat = @"<a href=""{0}""><img src=""{1}"" border=""0"" /></a>";

  36:     const string imageFormat = @"<img src=""{0}"" border=""0"" />";

  37:     var flexigrid = new FlexigridViewData {page = pageIndex, total = count};

  38:     foreach (var contact in pagedContacts)

  39:     {

  40:         flexigrid.rows.Add(new FlexigridRow

  41:         {

  42:             id = contact.ID,

  43:             cell = new List<string> 

  44:             { 

  45:                 string.Format(imageLinkFormat, ResolveUrl("~/Contact.mvc/Detail/" + contact.ID), 

  46:                 ResolveUrl("~/Images/Detail.gif")), 

  47:                 contact.ID.ToString(), 

  48:                 contact.FirstName, 

  49:                 contact.LastName, 

  50:                 contact.DateOfBirth.ToShortDateString(), 

  51:             }

  52:         });

  53:     }

  54:  

  55:     return flexigrid.ToJson();    

  56: }

Here are some helper extension methods that I used to complete the above code snippets.

   1: public static class JsonHelper

   2: {

   3:     public static string ToJson(this object obj)

   4:     {

   5:         var serializer = new JavaScriptSerializer();

   6:  

   7:         return serializer.Serialize( obj );

   8:     }

   9:  

  10:     public static string ToJson(this object obj, int recursionDepth)

  11:     {

  12:         var serializer = new JavaScriptSerializer();

  13:  

  14:         serializer.RecursionLimit = recursionDepth;

  15:  

  16:         return serializer.Serialize( obj );

  17:     }

  18: }

   1: public static T GetPropertyValue<T>(this object component, string propertyName)

   2: {

   3:     return (T) TypeDescriptor.GetProperties(component)[propertyName].GetValue(component);

   4: }

As a side note, I did have to dive into the JavaScript and fix two issues that I came across, but other than that it works like a charm.
I would prefer if the developer of the product had a better system of tracking bugs and maintaining a forum, but in the meantime what is setup is sufficient.

Design Pattern Riddle #8

If you need one or more actions,
I can be your design of choice.
I can organize your requests
or back them out, it's your choice.

Each object has it's parameters
That tells them how to act.
I am made of generic components;
Each one defines their internal pact.

a. Command

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Design Pattern Riddle #7

q. I'm in some ways like a elaborate disguise;
a window dressing concealing something immense.
I offer an unified perspective to numerous systems;
I excel at making complex things make sense.

a. Façade

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jQuery

I have recently started using jQuery and I’ve been quite impressed. I found integrating jQuery most useful while I developed my first ASP.NET MVC Preview 3 application.

jQuery was able to simplify some of the things I would have had to write nasty looking View code otherwise.

For example, I wanted to alternate every other row in a table with a different color. To do this in the View I initially created a counter variable and did a mod 2 to apply the CSS class. Once I integrated jQuery I was able to remove that messy code throughout my entire View and just replace it with…

   1: <script type="text/javascript">

   2:     $(document).ready(function(){

   3:         $("#tblList tr:odd").addClass("alternatingRow");

   4:         $("#tblList tr:even").addClass("row");

   5:     });

   6: </script>    

After I got a little familiar with jQuery I branched out and used it to create an accordion navigation menu with little effort.

   1: $("#menu li div.subMenuItems").hide();            

   2: $("#menu li div.parentMenuItem").click(function()

   3: {            

   4:     $("#menu li div.subMenuItems:visible").slideUp("slow");                

   5:     $(this).next().slideDown("slow");

   6:     return false;

   7: });

There are several other helpful areas in my ASP.NET MVC application that I found jQuery to be very convenient, efficient, and resulted in a cleaner code base.

If you haven’t used jQuery before I highly recommend you check it out.

ASP.NET AJAX 4.0 CodePlex Preview 1

The new version of ASP.NET AJAX is now available as a preview release.

The future of ASP.NET AJAX can be found in the Roadmap document hosted on the CodePlex website.

The preview 1 release contains somewhat complete versions of the following features

• Client-side template rendering
• Declarative instantiation of behaviors and controls
• DataView control
• Markup extensions
• Bindings

Feel free to download the preview yourself and kick the tires.

.NET 3.5 Framework Poster

For those of you who like a visual representation of your commonly used types and namespaces, then you are in luck! Microsoft has conveniently created a nice poster highlighting Microsoft Framework 3.5.

Feel free to download the full copy from their website.

Design Pattern Riddle #6

q. You might think I am the real thing,
But I'm just a thin outer case.
I typically call methods on another machine,
which might make bug tracking hard to trace.

a. Proxy

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Design Pattern Riddle #5

q. Some say that I have schizophrenia;
I change my behavior depending on my mood.
You might think I am someone else,
But I’m just a class with an attitude!

a. State

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Design Pattern Riddle #4

q. When there are many way to do one thing,
And you need to switch from that to this.
Just abstract away those different pieces;
Then you’ll be living in encapsulated bliss.

a. Strategy

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Design Pattern Riddle #3

q. You might call me a herald of the news
I distribute it to those that subscribe
Some say I follow the Hollywood principle,
But I’ll tell you that c# delegates and I jibe.

a. Observer

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Design Pattern Riddle #2

q. If you find yourself needing more functionality,
And your needs are dynamic and versatile,
Then I’m a good alternative to subclassing.
You will find that using me quite worthwhile.

a. Decorator

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Design Pattern Riddle #1

q. You use me quite often as you code with care;
I’m accessible to you just about everywhere.
I’m a solitary class, only one of me is made;
When you need me the most, I’ll come to your aid.

a. Singleton

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Quality Grin

q. If you are looking for quality,
I am a good place to begin
You can find me in VS 2008;
All the green will make you grin.

a. MSTest

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Concise Description

q. I don’t require you to repeat yourself,
But you might need to describe something twice.
I am most useful when it comes to LINQ;
You will find using me to be very concise.

a. Implicitly Typed Local Variables

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Compiler Inferred

q. You need to know the Object Initializer,
if you want to play with me.
I am inferred and created by the compiler;
before you know it I will flee.

Intellisense can pick me up and see me;
I am only readable inside.
I am useful when using LINQ;
where will you use me? You decide.

a. Anonymous Types

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Complex Line

q. I can setup your complex object;
I can do it while you assign.
I am not an overloaded constructor;
You can write me in one line.

a. Object Initializer

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