Lets look at an example.

void Main()
{

//Create a list of strings
List<string> cars = new List<string>
{
"Toyota",
"Lexus",
"Mercedes Benz",
"Bentley",
"BMW",
"Acura"
};
//Generate Lookup Structure based on length of string
var carList = cars.ToLookup (c => c.Length);

foreach (var car in carList[6])
{
Console.WriteLine(car);
}

}

Output:

Toyota
Bentley

In this example the ToLookup method receives a Func delegate which is specified as a lambda expression. A data structure is created which is indexed on the length of characters for each. One or more cars can have the same length (thus making it a lookup)

WebRoles & WorkerRoles:

Every Azure application consists of roles in the form of either WebRoles or WorkerRoles.Web roles are synonymous with ‘web applications’ while Worker roles are synonymous with ‘Windows services’.

Your typical web role would be a  ASP.NET web application which a user would typically interact with.The web role is designed for code that directly interacts with web browsers or other HTTP clients. It depends on IIS, Microsoft’s web server.

A worker role on the other hand is designed to be running all the time (just like a windows service). It starts up and is running all the time. It’s best use is typically for some kind of background processing.

Service Definition (CSDEF) file

Service Configuration (CSCFG) file

using System;
using System.Linq;
using System.Web.UI.WebControls;

public partial class Controls_DepartmentSelectorControl : System.Web.UI.UserControl
{

	private string selecteddepartment = string.Empty;
	public string SelectedDepartment
	{
		get { return selecteddepartment; }
		set
		{
			selecteddepartment = value;
			selecteddepartment = uxDepartments.SelectedItem.Text;
		}
	}

	//Create eventhandler to be consumed by the host page
	public event EventHandler SelectDepartment;

	protected void Page_Load(object sender, EventArgs e)
	{
		using (var context = new AdventureWorksEntities())
		{

			var departments = context.Departments.Select(p => new Department
			{
				DepartmentID = p.DepartmentID,
				GroupName = p.GroupName,
				Name = p.Name,
				ModifiedDate = p.ModifiedDate
			});
			foreach (var department in departments)
			{
				var dItem = new ListItem { Text = department.Name, Value = department.DepartmentID.ToString() };
				uxDepartments.Items.Add(dItem);
			}

		}

	}

	protected void uxDepartments_SelectedIndexChanged(object sender, EventArgs e)
	{
		//Set the member variable to what the user has selected
		selecteddepartment = uxDepartments.SelectedItem.Text;
		if(SelectDepartment != null)
		{
			//Event is raised and corresponding eventhandler is called to respond to the event
			SelectDepartment(this, new EventArgs());
		}

	}
}

Kentico CMS allows you to use a custom control called CMSEditableRegion. There are times when you might need to check the contents of this region and perform some checks to implement business rules.

Solution : Check for the EditableRegion property on the Current document

Each document has a property called EditableRegions which is basically a key value pair. If an editable region is on the page then the name (in lower case) is stored as a key in Editable Regions.

if (CMSContext.CurrentDocument.DocumentContent.EditableRegions.ContainsKey("uxpagetitle"))
{
         content = CMSContext.CurrentDocument.DocumentContent.EditableRegions["uxpagetitle"].ToString();
}

The iCalendar file is a fairly common feature which most developers add to enable  users to add events to their personalized calendars via a custom calendar application

Solution : Create a web handler which will create a plain text file with the ‘ics’ extension.

using System;
using System.Web;
namespace MyNamespace
{
 public class iCalendar: IHttpHandler
 {

  public bool IsReusable
  {
   get
   {
    return true;
   }
  }

  string DateFormat
  {
    get
    {
      return "yyyyMMddTHHmmssZ"; // 20060215T092000Z
    }
  }

  public void ProcessRequest(HttpContext context)
  {
   DateTime startDate = DateTime.Now.AddDays(5);
   DateTime endDate = startDate.AddMinutes(35);
   string organizer = "foo@bar.com";
   string location = "My House";
   string summary = "My Event";
   string description = "Please come to\\nMy House";

   context.Response.ContentType="text/calendar";
   context.Response.AddHeader("Content-disposition", "attachment; filename=appointment.ics");

   context.Response.Write("BEGIN:VCALENDAR");
   context.Response.Write("\nVERSION:2.0");
   context.Response.Write("\nMETHOD:PUBLISH");
   context.Response.Write("\nBEGIN:VEVENT");
   context.Response.Write("\nORGANIZER:MAILTO:" + organizer);
   context.Response.Write("\nDTSTART:" + startDate.ToUniversalTime().ToString(DateFormat));
   context.Response.Write("\nDTEND:" + endDate.ToUniversalTime().ToString(DateFormat));
   context.Response.Write("\nLOCATION:" + location);
   context.Response.Write("\nUID:" + DateTime.Now.ToUniversalTime().ToString(DateFormat) + "@mysite.com");
   context.Response.Write("\nDTSTAMP:" + DateTime.Now.ToUniversalTime().ToString(DateFormat));
   context.Response.Write("\nSUMMARY:" + summary);
   context.Response.Write("\nDESCRIPTION:" + description);
   context.Response.Write("\nPRIORITY:5");
   context.Response.Write("\nCLASS:PUBLIC");
   context.Response.Write("\nEND:VEVENT");
   context.Response.Write("\nEND:VCALENDAR");
   context.Response.End();
  }
 }
}

At this point Feature 1 is complete and we are ready to deploy to our sharepoint environment. You should have a solution explorer similar to this:

After you deploy, you can verify that everything worked by doing the following. Navigate to Site Actions -> Site Settings -> Site Collection Administration -> Site Collection Features. Search for the feature you deployed. You should find that it’s activated and working as expected.

The second thing we need to check is whether our master page was deployed or not. Navigate to  http://[RootSite]/_catalogs/master/Forms/AllItems.aspx in your browser. You should find that Test.master (or whatever the name you gave) is now visible and approved in our master page list.

At this point we have feature 1 fully working. We won’t stop here because we want this master page to be applied whenever a new site collection is provisioned. So we have to create our Stapler (Feature2) which will associate Feature1 with the site definition of My sites.

Step 3: Create Stapler Feature to associate Feature1 with a site Definition

Follows the same steps above to create another Feature called Feature 2. The scope of this feature should be set to Farm level.

Next add an empty element item called Elements.

Your Solution explorer should like this now

The next task is the most important since this involves associating feature with a site definition.

We will need the GUID from Feature1 . You can find this in the manifest.

<?xml version="1.0" encoding="utf-8"?>
<Elements xmlns="http://schemas.microsoft.com/sharepoint/">
<FeatureSiteTemplateAssociation TemplateName="SPSMSITEHOST#0" Id="493a82e4-f05b-4244-91df-c99ba69db085"></FeatureSiteTemplateAssociation>
<FeatureSiteTemplateAssociation TemplateName="SPSPERS#0" Id="493a82e4-f05b-4244-91df-c99ba69db085"></FeatureSiteTemplateAssociation>

</Elements>

Two lines of code were added to make the association between feature and site defintion. The site definition id is encapsulated in the templatename [SPSMITEHOST#0 & SPSPERS#0].

We’ve now successfully created our feature and stapler. Deploy this to your SharePoint instance to see this in action.

using (SPWeb spweb = SPContext.Current.Web) {
SPUser oUser = spweb.CurrentUser;
string Username = oUser.LoginName;
}

SPUser represents a user in SharePoint services. A new object (oUser) is created from the spweb property, currentUser. We can now access various other properties like LoginName, Name etc.

• CAML Builder from U2U (http://www.u2u.be/Res/Tools/CamlQueryBuilder.aspx): Build and test your CAML queries and paste into your code.
• CKS (Community Kit for SharePoint, Tools Edition) (http://cksdev.codeplex.com/ ): Makes the SharePoint development cycle tolerable (almost). Version 2 was released May 2011.
• ULS Viewer (http://archive.msdn.microsoft.com/ULSViewer ) In my opinion, the best.
• SharePoint Manager (http://spm.codeplex.com/). Invaluable for browsing a SharePoint farm, viewing and changing parameters and option.
• SharePoint Diagnostic Studio (http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=20022) is a great tool to help administer and manage SharePoint.

• SharePoint 2010 exposes list data through a REST service that you can consume in your projects.
• The WCF data service SharePoint exposes is ListData.svc. eg http://sp2010dev/_vti_bin/listdata.svc 
• You will need the ADO.NET client runtime installed on your machine
• In order to use the objects returned by listdata.svc service, we’ll need to generate entity classes for the list of objects returned by that service. You can do this by using SPMetal or adding a service reference to your project.

After adding a service reference , include the ff references in your project:

using System.Net;
using Microsoft.SharePoint.Linq

You’re now ready to write a simple program. We want to create a webpart which will display a list of events only created by a particular user.

In the page_Load of our visual webpart we create a new data context by specifiying a URI and credentials by which we will be connecting to the list data.

protected void Page_Load(object sender, EventArgs e)
		{

			var builder = new StringBuilder();
			var context = new POPDataContext(new Uri("http://sp2010dev/_vti_bin/listdata.svc"))
							  {
								  Credentials = CredentialCache.DefaultCredentials

							  };

Next we retrieve the username of the current user and strip away some default characters in the string. The query below then simple selects all events which were created by that user. We loop through all the results and assign them to a string which we display in our label.

SPUser currentUser = SPContext.Current.Web.CurrentUser;
			String activeDirectoryUsername = currentUser.LoginName;

			activeDirectoryUsername = activeDirectoryUsername.Substring(3);

var users =context.PopEvents.Where(b => b.CreatedBy.UserName.Equals(activeDirectoryUsername))
                                                .Select(b => new { b.Title,
                                                                   Username = b. CreatedBy.UserName
                                                                  });

foreach (var userInformationListItem in users)
			{
				builder.AppendFormat("{0} posted by {1}", userInformationListItem.Title,
									 userInformationListItem.Username);
				builder.AppendFormat("<br />");
			}

			uxVacationRequests.Text = builder.ToString();

		}

 Output:

Sharepoint: Cannot convert type ‘Microsoft.SharePoint.WebControls.ScriptLink’
to ‘System.Web.UI.IAttributeAccessor’

Whenever you copy a master page from one site to another in SharePoint designer, it converts certain tags to script. The solution is to cut and paste your code into a new masterpage file.

Source: http://www.hexanes.com/?p=448