When Bundling Stylesheets in MVC 4

Microsoft released the newest version of the MVC framework as part of their Visual Studio 2012 release this week. One of the features of this release is the bundling and minification capabilities. Bundling allows you to combine many resources such as stylesheets and scripts so that fewer requests are made to the server. An example on using this feature is below:

public class BundleConfig {
    public static void RegisterBundles(BundleCollection bundles) {
        // combine all of the jquery ui scripts into one bundle
        bundles.Add(new ScriptBundle("~/bundles/jqueryui").Include(
                "~/Scripts/jquery-ui-{version}.js"));

        // combine all of the jquery ui scripts into one bundle
        bundles.Add(new StyleBundle("~/content/themes/base/jquery").Include(
                "~/Content/themes/base/jquery.ui.core.css",
                "~/Content/themes/base/jquery.ui.resizable.css",
                "~/Content/themes/base/jquery.ui.selectable.css",
                "~/Content/themes/base/jquery.ui.accordion.css",
                "~/Content/themes/base/jquery.ui.autocomplete.css",
                "~/Content/themes/base/jquery.ui.button.css",
                "~/Content/themes/base/jquery.ui.dialog.css",
                "~/Content/themes/base/jquery.ui.slider.css",
                "~/Content/themes/base/jquery.ui.tabs.css",
                "~/Content/themes/base/jquery.ui.datepicker.css",
                "~/Content/themes/base/jquery.ui.progressbar.css",
                “~/Content/themes/base/jquery.ui.theme.css"));
    }
}

The above code creates bundles for the jQuery UI scripts and stylesheets. In order to use them in your view you do the following:

@Scripts.Render("~/bundles/jqueryui")
@Styles.Render("~/content/themes/base/jquery")

One thing you might be tempted to do when bundling your stylesheets is use a shorter name for your bundle such as "~/css/jqueryui", but there is one thing you need to be aware of when you do this. It is common for stylesheets to include references to images relative to the stylesheet directory. For example, the default jQuery UI theme is installed in the ~/Content/themes/base/ directory. Inside of that directory is an images/ folder that contains many of the sprites that jQuery UI uses. If you create a CSS bundle called "~/css/jqueryui" then you might notice that none of the jQuery UI icons work any more. This is because the content is expected to be relative to the directory that the stylesheet is in. When creating the bundle as ~/css/jqueryui, the images are expected to be in ~/css/images.
Unless you are running with debug=”false”, you might not even notice the problem. This is because by default, when running with debug=”true”, the ASP.net runtime will still make separate requests for every resource in your bundle. When changing to debug=”false”, ASP.net will actually combine all of the files in your bundle and make a single request (per bundle). The request might look similar to:
<link href="/css/jqueryui?v=ps9Ga9601PrzNA2SK3sQXlYmNW3igUv5FOdOPWptyus1" rel="stylesheet"/>
Since the request is being made to /css/jqueryui, the server expects that any relative paths are going to be relative to the /css directory. To fix this, you need to make sure your CSS bundle names are similar to the physical directory structure of your application. When installing the jQuery UI nuget package, it will put your stylesheets in the directory /content/themes/base/ so you should name your bundle "~/content/themes/base/jqueryui" to make sure that everything works.

How do we define a lambda expression?

Lambda basic definition: Parameters => Executed code.

Simple example

n => n % 2 == 1

n is the input parameter 
n % 2 == 1 is the expression

You can read n => n % 2 == 1 like: "input parameter named n goes to anonymous function which returns true if the input is odd".


 Same example (now execute the lambda):


List<int> numbers = new List<int>{11,37,52};
List<int> oddNumbers = numbers.where(n => n % 2 == 1).ToList();
//Now oddNumbers is equal to 11 and 37

Why do we need lambda expressions? (Why would we need to write a method without a name?)

Convenience. It's a shorthand that allows you to write a method in the same place you are going to use it. Especially useful in places where a method is being used only once, and the method definition is short. It saves you the effort of declaring and writing a separate method to the containing class.
Benefits:

1. Reduced typing. No need to specify the name of the function, its return type, and its access modifier. 
2. When reading the code you don't need to look elsewhere for the method's definition. 

Lambda expressions should be short. A complex definition makes the calling code difficult to read. 

What is a Lambda Expression?

A lambda expression is an anonymous function and it is mostly used to create delegates in LINQ. Simply put, it's a method without a declaration, i.e., access modifier, return value declaration, and name. 

How to find the tables used in stored procedures ?

;WITH stored_procedures AS (
SELECT
o.name AS proc_name, oo.name AS table_name,
ROW_NUMBER() OVER(partition by o.name,oo.name ORDER BY o.name,oo.name) AS row
FROM sysdepends d
INNER JOIN sysobjects o ON o.id=d.id
INNER JOIN sysobjects oo ON oo.id=d.depid
WHERE o.xtype = 'P')
SELECT proc_name, table_name FROM stored_procedures
WHERE row = 1
ORDER BY proc_name,table_name

Difference between Set-Based approach and Cursor-Based approach in SQL Server ?

Think of it this way. If your wife wants you to fold the washing that's come out of the tumble dryer - she might well say 'can you please fold the washing?'. That's a set based approach - it's an operation over a collection of items.
The cursor based approach would be the equivalent of your wife asking you to fold a t-shirt, then when you had come back with that asking you to fold a pair of trousers, then when you had come back with that, asking if you could fold a jumper. No doubt, that would really hack you off. SQL Server doesn't fare much better, and really prefers to be asked to do things the set based way.

When working in T-SQL, try to tell the system what you want to do with the data, not how you want it done.

What are the benefits of using Exists ?

Many times you're required to write query to determine if a record exists. Typically you use this to determine whether to insert or update a records. Using the EXISTS keyword is a great way to accomplish this.
Here's a simple example from the pubs database using EXISTS:

if EXISTS (select *
 from authors
 where au_id = '172-32-1176')
  Print 'Record exits - Update'
ELSE
  Print 'Record doesn''t exist - Insert'

The EXISTS function takes one parameter which is a SQL statement. If any records exist that match the criteria it returns true, otherwise it returns false. This gives you a clean, efficient way to write a stored procedure that does either an insert or update.
The other benefit of EXISTS is that once it finds a single record that matches it stops processing. This doesn't have a huge impact if you're checking on a primary key. It does have a big impact if you're checking for existance based on another field. Consider the following two queries:

if exists (select *
 from authors
 where state = 'ca')
  Print 'Record exits'
ELSE
  Print 'Record doesn''t exist'

if (select count(*)
 from authors
 where state = '172-32-1176') > 0
  Print 'Record exits'
ELSE
  Print 'Record doesn''t exist'

In the pubs database there are only 23 records in the authors table.  
Even with that small number of records, the IF EXISTS version runs 4 
times faster than selecting a count.  This is because it stops as soon 
as it finds a single record that matches the criteria.  The second 
statement must process all the rows that match.