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LINQ to Objects – 5 Minute Overview

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Modified: 2008/04/24 23:15 by t_magennis – Categorized as: LINQ to Objects, Samples

» LINQ to Objects – 5 Minute Overview » LINQ to Objects

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(See also: Main LINQ to Objects Page)

Popular Pages

What is LINQ?
LINQ to Objects – 5 minute overview
LINQ to SQL – 5 minute overview
LINQ to XML- 5 minute overview
Writing LINQ Queries

LINQ to Objects allows .NET developers to write “queries” over collections of objects. Out of the box there is a large set of query operators that provide a similar depth of functionality to what we expect from any SQL language working with a relational database, and if what we need isn’t present out-of-the-box, we can add our own.

Traditionally, working with collections of objects meant writing a lot of looping code using for loops or foreach loops to iterate through a list carrying out filtering using if statements, and some action like keeping a running sum of a total property. LINQ frees you from having to write looping code; it allows you to write queries that filter a list or calculate aggregate functions on elements in a collection as a set.

We can write queries against any collection type that implements an interface called IEnumerable (and also a new interface called IQueryable, but more on that later). This is almost any collection type built into the .NET class libraries including simple arrays like string[], or int[], and any List<T> collection we define. Let us look at a few of the simplest examples to understand the basic syntax.

int[] nums = new int[] {0,4,2,6,3,8,3,1};

 
 
var result = from n in nums
             where n < 5
             orderby n
             select n;
 
 
foreach(int i in result)

    Console.WriteLine(i);
 
 
Output:
0
1
2
3
3	

4

An example of calculating the aggregate sum of all the elements would look like –

int[] nums = new int[] {0,4,2,6,3,8,3,1};

 
int result = nums.Sum();
Console.WriteLine(result);
 
Output:
27

LINQ to Objects extends any type that inherits from IEnumerable (which is almost every collection class in .NET, from simple Arrays to List<T>) to support query operations similar to those available in SQL. We can write queries using any of the built-in Standard Query Operators, or add our own operators if we need to. The standard operators cover a wide variety of categories, at present there are over fifty that form the backbone of LINQ. To get an idea of their scope, here is a list of those operators available to us -

Operator Type	Operator Name
Aggregation	Aggregate, Average, Count, LongCount, Max, Min, Sum
Conversion	Cast, OfType, ToArray, ToDictionary, ToList, ToLookup, ToSequence
Element	DefaultIfEmpty, ElementAt, ElementAtOrDefault, First, FirstOrDefault, Last, LastOrDefault, Single, SingleOrDefault
Equality	EqualAll
Generation	Empty, Range, Repeat
Grouping	GroupBy
Joining	GroupJoin, Join
Ordering	OrderBy, ThenBy, OrderByDescending, ThenByDescending, Reverse
Partitioning	Skip, SkipWhile, Take, TakeWhile
Quantifiers	All, Any, Contains
Restriction	Where
Selection	Select, SelectMany
Set	Concat, Distinct, Except, Intersect, Union

Most of the operators should be familiar if you have ever worked with a relational database writing queries in SQL. One important distinction between writing SQL queries and LINQ queries is that the operator order is reversed. If you are used to Select-From-Where-OrderBy, it might take some time to overcome the muscle memory and move to From-Where-OrderBy-Select.

To demonstrate some of LINQ’s query capabilities let us write a few queries over this data.

First Name	Last Name	D.O.B.	Phone	State
Barney	Gottshall	19-Oct-1945	885 983 8858	CA
Armando	Valdes	9-Dec-1973	848 553 8487	WA
Adam	Gauwain	3-Oct-1959	115 999 1154	AK
Jeffery	Deane	16-Dec-1950	677 602 6774	CA
Collin	Zeeman	10-Feb-1935	603 303 6030	FL
Stewart	Kagel	20-Feb-1950	546 607 5462	WA
Chance	Lard	21-Oct-1951	278 918 2789	WA
Blaine	Reifsteck	18-May-1946	715 920 7157	TX
Mack	Kamph	17-Sep-1977	364 202 3644	TX
Ariel	Hazelgrove	23-May-1922	165 737 1656	OR

Sample Contact data

List<Contacts> contacts = Contacts.SampleData();

 
var q = from c in contacts
        where c.DateOfBirth.AddYears(35) > DateTime.Now
        orderby c.DateOfBirth descending
        select c.FirstName + " " + c.LastName +
               " b." + c.DateOfBirth.ToString("dd-MMM-yyyy");

 
foreach(string s in q)
    Console.WriteLine(s);
 
Output:
Mack Kamph b.17-Sep-1977

Armando Valdes b.09-Dec-1973

The previous example demonstrates how to get a list of contacts who are less than 35 years of age sorted in descending order by age. This query builds a list of formatted strings as the result, but any type can be returned, even an anonymous type (a type we haven’t explicitly defined that holds just our data, but more on that later). Figure 6 demonstrates grouping, which allows you to create a sub-collection of elements based on a value by using the group by construct.

List<Contacts> contacts = Contacts.SampleData();
 
var q = from c in contacts
        group c by c.State;

 
foreach(var group in q) {
    Console.WriteLine("State: " + group.Key);
        foreach(Contacts c in group)

            Console.WriteLine("  {0) {1}", c.FirstName, c.LastName);
}
 
Output:
State: CA
  Barney Gottshall
  Jeffery Deane
State: WA
  Armando Valdes
  Stewart Kagel
  Chance Lard
State: AK
  Adam Gauwain
State: FL
  Collin Zeeman
State: TX
  Blaine Reifsteck
  Mack Kamph
State: OR
  Ariel Hazelgrove

A key aspect of accessing relational data is the concept of joining. SQL languages have powerful join capabilities to allow queries to be written against normalized data which is a fancy term for not repeating data, by separating data across multiple tables linking by a common value. LINQ allows you to join multiple object collections together using syntax similar to SQL. To demonstrate, in addition to the data shown in Sample Contact data, also consider the following call log data.

Number	Duration (mins)	Incoming	Date	Time
885 983 8858	2	TRUE	7-Aug-2006	8:12
165 737 1656	15	TRUE	7-Aug-2006	9:23
364 202 3644	1	FALSE	7-Aug-2006	10:5
603 303 6030	2	FALSE	7-Aug-2006	10:35
546 607 5462	4	TRUE	7-Aug-2006	11:15
885 983 8858	15	FALSE	7-Aug-2006	13:12
885 983 8858	3	TRUE	7-Aug-2006	13:47
546 607 5462	1	FALSE	7-Aug-2006	20:34
546 607 5462	3	FALSE	8-Aug-2006	10:10
603 303 6030	23	FALSE	8-Aug-2006	10:40
848 553 8487	3	FALSE	8-Aug-2006	14:0
848 553 8487	7	TRUE	8-Aug-2006	14:37
278 918 2789	6	TRUE	8-Aug-2006	15:23
364 202 3644	20	TRUE	8-Aug-2006	17:12

Sample Call Log data

To join the call log data and retrieve the contact name that matches the phone number we would use the following query.

 
    List<Contacts> contacts = Contacts.SampleData();
    List<CallLog> callLog = CallLog.SampleData();
 
 
    var q = from call in callLog
            join contact in contacts on call.Number equals contact.Phone

            select new {contact.FirstName, contact.LastName,
                        call.When, call.Duration};

     foreach(var call in q)

         Console.WriteLine(“{0} – {1) {2) ({3}min)”,
                           call.When.ToString("ddMMM HH:m"),
                           call.FirstName, call.LastName, call.Duration);

 
Output:
07Aug 08:12 - Barney Gottshall (2min)
07Aug 09:23 - Ariel Hazelgrove (15min)

07Aug 10:5 - Mack Kamph (1min)
07Aug 10:35 - Collin Zeeman (2min)
07Aug 11:15 - Stewart Kagel (4min)

07Aug 13:12 - Barney Gottshall (15min)
07Aug 13:47 - Barney Gottshall (3min)
07Aug 20:34 - Stewart Kagel (1min)

08Aug 10:10 - Stewart Kagel (3min)
08Aug 10:40 - Collin Zeeman (23min)
08Aug 14:0 - Armando Valdes (3min)

08Aug 14:37 - Armando Valdes (7min)
08Aug 15:23 - Chance Lard (6min)
08Aug 17:12 - Mack Kamph (20min)

This query joins call records with contact data via the phone number.

Going one step further and summarizing data from multiple collections by combining filtering, grouping, joining and aggregate functions all in one query expression, we can demonstrate the power of Query Expressions on in-memory data. The following example show incoming call records from each contact and the aggregate call statistics.

    List<Contacts> contacts = Contacts.SampleData();
    List<CallLog> callLog = CallLog.SampleData();
 

    var q = from call in callLog
            where call.Incoming == true
            group call by call.Number into g
            join contact in contacts on g.Key equals contact.Phone

            orderby contact.FirstName, contact.LastName
            select new { contact.FirstName, contact.LastName,
                         Count = g.Count(),
                         Avg   = g.Average( c => c.Duration ),
                         Total = g.Sum( c => c.Duration )};

    foreach(var call in q)

        Console.WriteLine("{0} {1} - Calls:{2}, Time:{3}mins, Avg:{4}mins",
            call.FirstName, call.LastName,
            call.Count, call.Total, Math.Round(call.Avg, 2));

 
Output:
Ariel Hazelgrove - Calls:1, Time:15mins, Avg:15mins
Armando Valdes - Calls:1, Time:7mins, Avg:7mins
Barney Gottshall - Calls:2, Time:5mins, Avg:2.5mins
Chance Lard - Calls:1, Time:6mins, Avg:6mins
Mack Kamph - Calls:1, Time:20mins, Avg:20mins
Stewart Kagel - Calls:1, Time:4mins, Avg:4mins

This example shows filtering, ordering, grouping, joining and selection using aggregate values.

(See also: Main LINQ to Objects Page)

Popular Pages
What is LINQ?
LINQ to Objects – 5 minute overview
LINQ to SQL – 5 minute overview
LINQ to XML- 5 minute overview
Writing LINQ Queries

LINQ to Object – 5 Minute Overview is Copyright © Troy Magennis.

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1. Webform Uses the ‘Page Controller’ pattern. Each page has a code-behind class that acts as a controller and is responsible for rendering the layout. MVC Uses the ‘Front Controller’ pattern. There is a single central controller for all pages to process web application requests and facilitates a rich routing architecture.
2. Webform Uses an architecture that combines the Controller (code behind) and the View (.aspx). Thus the Controller has a dependency on the View. Due to this, testing and maintainability becomes an issue. MVC enforces a “separation of concerns”. The Model does not know anything about the View. The View does not know there’s a Controller. This makes MVC applications easier to test and maintain.
3. In Webform the view is called before the controller, while in MVC Controller renders View based on actions as a result of the User Interactions on the UI.
4. At Webforms core, you ‘cannot’ test your controller without instantiating a View. There are ways to get around it using tools. While ASP.NET MVC was designed to make test-driven development easier. You ‘can’ test your Controller without instantiating a View and carry out unit-tests without having to run the controllers in an ASP.NET process.
5. WebForms manage state by using Viewstate and server-based controls. While MVC does not maintain state information by using Viewstate.
6. WebForms support an event-driven programming style that is like Windows applications and is abstracted from the user. The State management is made transparent by using sessions, Viewstate etc… In the process, the HTML output is not clean making it difficult to manage later. The ViewState also increases your page size. In ASP.NET MVC, the output is clean and you have full control over the rendered HTML. The orientation is towards building standard compliant pages and provides full control over the behavior of an application.
7. Deep understanding of HTML, CSS and JavaScript is not required to a large extent since the WebForm model abstracts a lot of these details and provides automatic plumbing. While abstracting details to provide ease of use, sometimes a solution is overcomplicated, than it needs to be. In MVC, A thorough understanding of how HTML, CSS and JavaScript work together is required. The advantage is you can do a lot of jQuery and AJAX stuff in an efficient and simple manner than you would do in an ASP.NET application.
8. WebForms can drastically reduce time while building up intranet and internet applications that use a lot of controls (drag and drop model). Although this is true for development, a lot of time is spent later to code around limitations. In MVC, You lose the ‘drag and drop’ quick model of building your web applications. The focus is on control over the application behavior and test-driven development. The model is extensible and you do not have to spend time working around limitations.
9. Relatively simple to learn and pickup. Works very well for developers who initially have trouble with the HTTP/HTML model and are coming from a similar WinForms oriented event model. In MVC, There is a learning curve to understand the why, when and how of ASP.NET MVC.
10. Lesser amount of code is required to build Webapps since a lot of components are integrated and provided out of the box. You can also use a lot of data controls provided out of the box that rely on ViewState. In MVC, since the application tasks are separated into different components, amount of code required is more. Since ASP.NET MVC does not use ViewState, you cannot use Data controls like GridView, Repeater.
11. Webforms works very well for small teams where focus is on rapid application development. MVC works well for large projects where focus in on testability and maintainability.

Say you’re building a web application and you want, against your better judgment perhaps, to allow end users to easily customize the look and feel – a common scenario within a blog engine or any hosted application.

With ASP.NET, view code tends to be some complex declarative markup stuck in a file on disk which gets compiled by ASP.NET into an assembly. Most system administrators would first pluck out their own toenail rather than allow an end user permission to modify such files.

It’s possible to store such files in the database and use a VirtualPathProvider to load them, but that requires your application (and thus their views) to run in full trust. Is there a way you could safely store such views in the database in an application running in medium trust where the code in the view is approachable?

At the ALT.NET conference a little while back, Jimmy Schementi and John Lam gave a talk about the pattern of hosting a scripting language within a larger application. For example, many modern 3-D Games have their high performance core engine written in C++ and Assembly. However, these games often use a scripting language, such as Lua, to write the scripts for the behaviors of characters and objects.

An example that might be more familiar to more people is the use of VBA to write macros for Excel. In both of these cases, the larger application hosts a scripting environment that allow end users to customize the application using a simpler lighter weight language than the one the core app is written in.

A long while back, I wrote a blog post about defining ASP.NET MVC Views in IronRuby followed by a full IronRuby ASP.NET MVC stack. While there was some passionate interest by a few, in general, I was met with the thunderous sound of crickets. Why the huge lack of interest? Probably because I didn’t really sell the benefit and the explain the pain it solves. I’m sure many of you were asking, Why bother? What’s in it for me?

After thinking about it some more, I realized that my prototypes appeared to suggest that if you want to take advantage of IronRuby, you would need to make some sort of wholesale switch to a new foreign language, not something to be undertaken lightly.

This is why I really like Jimmy and John’s recent efforts to focus on showing the benefits of hosting the DLR for scripting scenarios like the ones mentioned above. It makes total sense to me when I look at it in this perspective. The way I see it, most developers spend a huge bulk of their time in a single core language, typically their “language of choice”. For me, I spend the bulk of my time writing C# code.

However, I don’t think twice about the fact that I also write tons of JavaScript when I do web development, and I’ll write the occasional VB code when I need a new Macro for Visual Studio or Excel. I also write SQL when I need to. I’m happy to pick up and use a new language when it will enable me to do the job at hand more efficiently and naturally than C# does. I imagine many developers feel this way. The occasional use of a scripting languages is fine when it gets the job done and I can still spend most of my time in my favorite language.

So I started thinking about how that might work in a web application. What if you could write all your business logic and controller logic in your language of choice, but have your views written in a light weight scripting language. If my web application were to host a scripting engine, I could actually store the code in any medium I want, such as the database. Having them in the database makes it very easy for end users to modify it since it wouldn’t require file upload permissions into the web root.

This is where hosting the DLR is a nice fit. I put together a proof of concept for these ideas. This is just a prototype intended to show how such a workflow might work. In this prototype, you go about creating your models and controllers the way you normally would.

For example, here’s a controller that returns some structured data to the view in the form of an anonymous type.

public ActionResult FunWithScripting()
{
var someData = new {
salutation = "Are you having fun with scripting yet?",
theDate = DateTime.Now,
numbers = new int[] { 1, 2, 3, 4 }
};
return View(someData);
}

Once you write your controller, but before you create your view, you compile the app and then go visit the URL.

We haven’t created the view yet, so let’s follow the instructions and login. Afterwards, we this:

Since the view doesn’t exist, I hooked in and provided a temporary view for the controller action which contains a view editor. Notice that at the bottom of the screen, you can see the current property names and values being passed to the view. For example, there’s an enumeration of integers as one property, so I was able to use the Ruby each method to print them out in the view.

The sweet little browser based source code editor is named Edit Area created by Christophe Dolivet. Unfortunately, at the time I write this, it doesn’t yet have support for ERB style syntax highlighting schemes. That’s why the <% and %> aren’t highlighted in yellow.

When I click Create View, I get taken back to the request for the same action, but now I can see the view I just created (click to enlarge).

In the future, I should be able to host C# views in this way. Mono already has a tool for dynamically compiling C# code passed in as a string which I could try and incorporate.

I’m seriously thinking of making this the approach for building skins in a future version of Subtext. That would make skin installation drop dead simple and not require any file directory access. Let me know if you make use of this technique in your applications.

If you try and run this prototype, please note that there are some quirky caching issues with editing existing views in the prototype. It’ll seem like your view is not being edited, but it’s a result of how views are being cached. It might take a bit of time before your edits show up. I’m sure there are other bugs I’m still in the process of fixing. But for the most part, the general principle is sound.

You can download the prototype here.
]]> http://jenifertrinh.wordpress.com/2009/09/11/scripting-asp-net-mvc-views-stored-in-the-database/feed/ 0 jenifertrinh View does not exist view view editor Fun with scripting view http://jenifertrinh.wordpress.com/2009/09/11/bin-deploying-asp-net-mvc/ http://jenifertrinh.wordpress.com/2009/09/11/bin-deploying-asp-net-mvc/#comments Fri, 11 Sep 2009 23:17:28 +0000 jenifertrinh http://jenifertrinh.wordpress.com/?p=9 ]]> With the release of ASP.NET MVC Beta, the assemblies distributed with ASP.NET MVC are automatically installed into the GAC.

• System.Web.Mvc
• System.Web.Routing
• System.Web.Abstractions

While developing an application locally, this isn’t a problem. But when you are ready to deploy your application to a hosting provider, this might well be a problem if the hoster does not have the ASP.NET MVC assemblies installed in the GAC.

Fortunately, ASP.NET MVC is still bin-deployable. If your hosting provider has ASP.NET 3.5 SP1 installed, then you’ll only need to include the MVC DLL. If your hosting provider is still on ASP.NET 3.5, then you’ll need to deploy all three. It turns out that it’s really easy to do so.

Also, ASP.NET MVC runs in Medium Trust, so it should work with most hosting providers’ Medium Trust policies. It’s always possible that a hosting provider customizes their Medium Trust policy to be draconian.

What I like to do is use the Publish feature of Visual Studio to publish to a local directory and then upload the files to my hosting provider. If your hosting provider supports FTP, you can often skip this intermediate step and publish directly to the FTP site.

The first thing I do in preparation is to go to my MVC web application project and expand the References node in the project tree. Select the aforementioned three assemblies and in the Properties dialog, set Copy Local to True.

Now just right click on your application and select Publish.

This brings up the following Publish wizard.

Notice that in this example, I selected a local directory. When I hit Publish, all the files needed to deploy my app are available in the directory I chose, including the assemblies that were in the GAC.

Now I am ready to XCOPY the application to my host, but before I do that, I really should test the application as a bin deployed app to be on the safe side.

Ideally, I would deploy this to some staging server, or a virtual machine that does not have ASP.NET MVC installed. Otherwise, I’m forced to uninstall ASP.NET MVC on the current machine and then test the application.

You might be wondering, as I did, why I can’t just use gacutil to temporarily unregister the assembly, test the app, then use it again to register the assembly. Because it was installed using an MSI, Windows won’t let you unregister it. Here’s a command prompt window that shows what I got when I tried.

Notice that it says that “assembly is required by one or more applications”. In general, there shouldn’t be any difference between running your application with MVC gac’d and it ungac’d. But I wouldn’t trust me saying this, I’d test it out to be sure.

Bài 1:  ASP.NET MVC Framework

Một hạn chế của framework ASP.NET từ trước đến nay là không hỗ trợ các lập trình viên sử dụng kiến trúc MVC để phát triển các ứng dụng, và nhiều người vẫn đang mong chờ sự xuất hiện của kiến trúc lâu năm này trong bộ framework.

Tuần trước, tại hội nghị Alt.NET ở Austin, tôi đã có một bài thuyết minh về một framework MVC mới cho ASP.NET mà nhóm của chúng tôi đang thực hiện. Bạn có thể xem đoạn video về bài thuyết trình của tôi ở trang nhật ký của Scott Hanselman.

Chúng tôi sẽ phát hành bản preview của framework MVC ASP.NET cho mọi người vào cuối năm nay. Dự kiến chúng tôi sẽ cho ra đời bản chính thức và được hỗ trợ đầy đủ vào nửa đầu của năm 2009.

Model View Controller (MVC) là gì ?

MCV là tên một phương pháp chia nhỏ một ứng dụng thành ba thành phần để cài đặt, mỗi thành phần đóng một vai trò khác nhau và ảnh hưởng lẫn nhau, đó là models, views, và controllers. Models trong các ứng dụng dựa trên MVC là những thành phần có nhiệm vụ lưu trữ thông tin, trạng thái của các đối tượng, thông thường nó là một lớp được ánh xạ từ một bảng trong CSDL. Lấy ví dụ, chúng ta có lớp Product được sử dụng để mô tả dữ liệu từ bảng Products trong SQL, bao gồm ProductID, OrderDate… Còn đối với Views, nó chính là các thành phần chịu trách nhiệm hiển thị các thông tin lên cho người dùng thông qua giao diện. Thông thường, các thông tin cần hiển thị được lấy từ thành phần Models. Ví dụ, đối tượng Product có một “Edit” view bao gồm các textboxes, các dropdowns và checkboxes để chỉnh sửa các thuộc tính của sản phẩm; có một “Display” view gồm 2 dòng, cột dòng là ProductID, dòng sau là OrderDate… để xem thông tin về sản phẩm. Cuối cùng, Controllers trong các ứng dụng kiểu MVC chịu trách nhiệm xử lý các tác động về mặt giao diện, các thao tác đối với models, và cuối cùng là chọn một view thích hợp để hiển thị ra màn hình. Trong kiến trúc MVC, view chỉ có tác dụng hiển thị giao diện mà thôi, còn điều kiển dòng nhập xuất của người dùng vẫn do Controllers đảm trách.

Một lợi điểm của phương pháp MVC là nó bắt buộc phải tạo ra một sự rành mạch trong liên kết giữa 3 thành phần models, views và controllers trong ứng dụng. Duy trì được mối quan hệ rành mạch rõ ràng này khiến việc kiểm tra ứng dụng trở nên dễ dàng hơn, đồng thời trách nhiệm của từng thành phần được định nghĩa rõ ràng và cả ba đều làm việc ăn ý với nhau.

Pattern MVC cũng cho phép thực hiện red/green test driven development (TDD), cài đặt các unit tests tự động, xác định và kiểm tra lại các yêu cầu trước khi bắt tay vào viết code.
*** Test-Driven Development (TDD) is a software development technique consisting of short iterations where new test cases covering the desired improvement or new functionality are written first, then the production code necessary to pass the tests is implemented, and finally the software is refactored to accommodate changes.

Một vài chi tiết mà tôi có thể hé lộ vào thời điểm hiện tại, đó là:

- Cho phép sự chia tách rành mạch giữa các thành phần, mỗi thành phần đều có khả năng được test riêng biệt và mặc định hỗ trợ TDD. Tất cả các mối liên hệ chính yếu trong MVC đều có giao diện để hiển thị và đều có thể xây dựng thành các mô hình, và bao gồm interface-based IHttpRequest/IHttpResponse. Bạn có thể chạy unit test cho ứng dụng mà không phải chạy các Controllers trong ASP.NET process, điều này làm unit test chạy nhanh hơn. Bạn có thể sử dụng unit testing framework nào cũng được, kể cả NUnit, MBUnit, MS Test…

- Được thiết kế để có thể dễ mở rộng và tiện dụng, tất cả mọi thứ trong MVC framework đều có thể nhanh chóng được thay đổi, tùy chọn hóa. Ví dụ bạn có thể viết một View và sử dụng cho nhiều ứng dụng khác nhau, đây là tính pluggable.

- Bao gồm thành phần ánh xạ URL cho phép bạn xây dựng các ứng dụng thân thiện với bộ máy tìm kiếm và với người dùng. Lấy ví dụ tôi có thể ánh xạ URL /products/edit/4 là một trang cho phép chỉnh sửa thông tin về các sản phẩm, hoặc là /Blogs/scottgu/10-10-2007/SomeTopic/  để xem các thông tin.

- MVC framework hỗ trợ sử dụng các các tập tin .ASPX, .ASCX và .Master như là thành phần View, điều đó có nghĩa là bạn vẫn có thể sử dụng các tính năng của ASP.NET như master pages, <%= %> snippets, server controls, templates, data-binding, localization… Tuy nhiên nó không sử dụng mô hình post-back từ giao diện gửi đến server nữa, thay vào đó, bạn có thể chủ động đưa những post-back từ giao diện đó đến thẳng lớp Controller. Tóm lại, không còn viewstate hay là page lifecycle còn tồn tại trong mô hình MVC.

- Vẫn tiếp tục hỗ trợ các tính năng ASP.NET như là forms/windows authentication, URL authorization, membership/roles, output and data caching, session/profile state management, health monitoring, configuration system, the provider architecture…

Tổng kết

Nếu bạn đang tìm kiếm một phương pháp xây dựng các ứng dụng web theo hướng MVC, tôi nghĩ ASP.NET MVC Framework mới ra này sẽ là một lựa chọn tốt, rất rành mạch và dễ sử dụng. Nó cho phép bạn dễ dàng bảo trì sự phân tách giữa các thành phần trong ứng dụng, đồng thời cũng rất tốt trong công việc testing và TDD.

Tôi sẽ viết nhiều bài hướng dẫn hơn trong những tuần sắp đến để mô tả cách thức làm việc của MVC, để cho bạn có thể nhận ra những ưu điểm và thuận lợi khi sử dụng công nghệ này.

Hy vọng những điều tôi viết nãy giờ là có ích
Scott