{"id":321,"date":"2011-05-16T18:18:44","date_gmt":"2011-05-16T10:18:44","guid":{"rendered":"http:\/\/www.sharepointboost.com\/blog\/?p=321"},"modified":"2023-07-31T11:41:02","modified_gmt":"2023-07-31T03:41:02","slug":"extend-sharepoint-object-model-with-c-3-0-extension-methods","status":"publish","type":"post","link":"https:\/\/www.boostsolutions.com\/blog\/extend-sharepoint-object-model-with-c-3-0-extension-methods\/","title":{"rendered":"Extend SharePoint Object Model with C# 3.0 Extension Methods"},"content":{"rendered":"
C# 3.0 and .Net Framework 3.5 in introduce several new features. One of them is extension methods. Extension methods enable you to “add” new methods to the existing types. Extension methods are a special kind of static methods, but they are called as same as the instance methods. In this blog I will show you how to extend SharePoint API by using extension methods.<\/div>\n
Here are my extension methods for “SPList” object.<\/div>\n
\n\n\n\n
using System;
\nusing Microsoft.SharePoint;
\nnamespace ConsoleApplication1.ExtensionMethods
\n{ <\/p>\n
\/\/ Extension methods must be defined in a static class.
\npublic static class SPListExtension
\n{<\/div>\n
\/\/ This is the extension method.
\n\/\/ The first parameter takes the \"this\" modifier.
\npublic static string GetFullUrl(this SPList list)
\n{<\/div>\n
return string.Format(\"{0}\/{1}\", list.ParentWeb.Url, list.RootFolder.Url);<\/div>\n
}
\npublic static bool HasView(this SPList list, string viewName)
\n{<\/div>\n
if (string.IsNullOrEmpty(viewName))
\n{<\/div>\n
return false;<\/div>\n
}
\nforeach (SPView view in list.Views)
\n{<\/div>\n
if (view.Title.Equals(viewName, StringComparison.InvariantCultureIgnoreCase))
\n{<\/div>\n
return true;<\/div>\n
}<\/div>\n
}
\nreturn false;<\/div>\n
}<\/div>\n
}<\/div>\n
}<\/div>\n

<\/code> <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

<\/div>\n
Application with the extension methods<\/div>\n
\n\n\n\n
 <\/p>\n
using System;
\nusing ConsoleApplication1.ExtensionMethods;
\nusing Microsoft.SharePoint;
\nnamespace ConsoleApplication1
\n{<\/div>\n
class Program
\n{<\/div>\n
static void Main(string[] args)
\n{<\/div>\n
using (SPSite site = new SPSite(\"http:\/\/localhost\"))
\n{<\/div>\n
using (SPWeb web = site.OpenWeb())
\n{<\/div>\n
SPList list = web.Lists[\"Tasks\"];
\nConsole.WriteLine(string.Format(\"The full url of Tasks is: {0}\", list.GetFullUrl()));\/\/ Call an extension mothod.
\nConsole.WriteLine();
\nstring viewName = \"My Tasks\";
\nConsole.WriteLine(\"View Name: My Tasks\");
\nConsole.WriteLine(list.HasView(viewName)); \/\/ Call an extension mothod.
\nConsole.WriteLine();
\nviewName = \"abc 123\";
\nConsole.WriteLine(\"View Name: abc 123\");
\nConsole.WriteLine(SPListExtension.HasView(list, viewName)); \/\/ Try calling the extension method as a static method.<\/div>\n
}<\/div>\n
}
\nConsole.Read();<\/div>\n
}<\/div>\n
}<\/div>\n
}<\/div>\n

<\/code> <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

You also can call the extension methods as static methods.<\/div>\n<\/div>\n
Output with the extension methods<\/div>\n
\"\"<\/a><\/div>\n
<\/a><\/div>\n
Extension methods in C# 2.0<\/strong><\/div>\n
As I stated in the introduction to this article, the extension methods is a new feature of C# 3.0, and the SharePoint 2007 API is based on .NET Framework 2.0. If you try to use extension methods in a project targeting .NET Framework 2.0, you will get a compiler error when compiling your code, the error text is “Cannot define a new extension method because the compiler required type ‘System.Runtime.CompilerServices.ExtensionAttribute’ cannot be found”. Seems the compiler just needs to resolve ‘System.Runtime.CompilerServices.ExtensionAttribute’ to compile extension methods. So you can introduce your own ‘System.Runtime.CompilerServices.ExtensionAttribute’ class, then it worked correctly!<\/div>\n
\n\n\n\n
 <\/p>\n
namespace System.Runtime.CompilerServices<\/div>\n
{<\/div>\n
[AttributeUsage(AttributeTargets.Method | AttributeTargets.Class | AttributeTargets.Assembly)]<\/div>\n
public sealed class ExtensionAttribute : Attribute<\/div>\n
{<\/div>\n
}<\/div>\n
}<\/div>\n

<\/code> <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

The brilliant workaround explained by Daniel Moth.<\/div>\n<\/div>\n
The syntax with extension methods is much more streamline and a lot easier to understand. It easier for developers to approach the object model without having to divide their attention between the SharePoint API and custom class libraries.<\/div>\n","protected":false},"excerpt":{"rendered":"

C# 3.0 and .Net Framework 3.5 in introduce several new features. One of them is extension methods. Extension methods enable you to “add” new methods to the existing types. Extension methods are a special kind of static methods, but they are called as same as the instance methods. In this blog I will show you […]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[125],"tags":[62,64,63,486,65,66,27],"_links":{"self":[{"href":"https:\/\/www.boostsolutions.com\/blog\/wp-json\/wp\/v2\/posts\/321"}],"collection":[{"href":"https:\/\/www.boostsolutions.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.boostsolutions.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.boostsolutions.com\/blog\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/www.boostsolutions.com\/blog\/wp-json\/wp\/v2\/comments?post=321"}],"version-history":[{"count":38,"href":"https:\/\/www.boostsolutions.com\/blog\/wp-json\/wp\/v2\/posts\/321\/revisions"}],"predecessor-version":[{"id":525,"href":"https:\/\/www.boostsolutions.com\/blog\/wp-json\/wp\/v2\/posts\/321\/revisions\/525"}],"wp:attachment":[{"href":"https:\/\/www.boostsolutions.com\/blog\/wp-json\/wp\/v2\/media?parent=321"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.boostsolutions.com\/blog\/wp-json\/wp\/v2\/categories?post=321"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.boostsolutions.com\/blog\/wp-json\/wp\/v2\/tags?post=321"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}