SharePoint 2010: Visual Web Parts and LINQ

BANGALORE, INDIA: Web parts are one of the most important features of SharePoint. In SharePoint 2010 along with Visual Studio 2010, you get the ability to create new webparts visually rather than completely in code. We will take a look at doing this in this article. We will also explore the new LINQ to SharePoint capability — allowing developers to query SharePoint data using Language Integrated Query rather than writing failry obtuse CAML code.

Visual Web Parts

Visual Web Parts are a project type in Visual Studio 2010 that allow you to create Web parts quickly and easily. Open up VS2010 and create a new “Visual Web Part” solution. When prompted, enter the URL of the SharePoint site to which this Web Part will belong. Once the project is created, expand the “VisualWebPart1” element in Solution Explorer. Open the VisualWebPart1.webpart file. Change the Title property to “My LINQ Web Part” or something appropriate. Now open up the VisualWebPart1.ascx file, add some appropriate SharePoint or ASP.NET controls in it, add some code behind in the .cs file and compile the project. For instance, I added a SharePoint DateTimeControl and a label and added some code to display the selected date in the label every time.

Right click the solution in VS2010 and select “Deploy”. This will build the solution and deploy it to the SharePoint site you had configured in the beginning. Browse over to this site ,and on a page click the “Edit page” button on the Ribbon. Select your Webpart from the “Custom” folder and click the Add button. You will see the Web part showing up on the page. Simply save the page and then interact with your Web part. It should work just fine.

For instance in my Web Part, the .ascx file looks like this:

<%@ Assembly Name="$SharePoint.Project.AssemblyFullName$" %>

<%@ Assembly Name="Microsoft.Web.CommandUI, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>

<%@ Register Tagprefix="SharePoint" Namespace="Microsoft.SharePoint.WebControls" Assembly="Microsoft.SharePoint, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>

<%@ Register Tagprefix="Utilities" Namespace="Microsoft.SharePoint.Utilities" Assembly="Microsoft.SharePoint, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>

<%@ Register Tagprefix="asp" Namespace="System.Web.UI" Assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" %>

<%@ Import Namespace="Microsoft.SharePoint" %>

<%@ Register Tagprefix="WebPartPages" Namespace="Microsoft.SharePoint.WebPartPages" Assembly="Microsoft.SharePoint, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>

<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="VisualWebPart1UserControl.ascx.cs" Inherits="LinqVWP.VisualWeb Part1.VisualWebPart1UserControl" %>

asp:Label>

The last two lines are the ones that specify the SharePoint date time control and a label. The code behind for this looks like this:

protected void Page_Load(object sender, EventArgs e)

{ DateTime dt = DateTime.Now;

if (!String.IsNullOrEmpty(Request.QueryString<"date">))

dt = DateTime.Parse(Request.QueryString<"date">);

DateTimeControl1.SelectedDate = dt;

}

protected void Date_Changed(object sender, EventArgs e)

{

Label1.Text = DateTimeControl1.SelectedDate.ToString();

}

When this WebPart is run, it displays the selected Date and Time in the label.

{#PageBreak#}

LINQ To SharePoint

This is a new feature in SharePoint 2010 that allows developers to query data within SharePoint “elements” such as Lists and Libraries and manipulate them using the easy to learn and use LINQ. If you know LINQ, it becomes extremely easy to work with this. To try this out, first create a simple List — such as a Task list in the site where the above Web part was created. Now you need to create the LINQ to SharePoint classes to be used in the WebPart. For this open up a command prompt and type in the following commands:

set path=%path%;c:\program files\common files\microsoft shared\web server extensions\14\bin

spmetal.exe /web:http://Win08R2/Demo02 /namespace:LinqVWP.VisualWebPart1 /code:SPLinq.cs

 

An example of a simple VWP where the selected date and time is being displayed.

These commands will create a SPLinq.cs file that contains the entities for the objects in the site. Back in VS2010, add this file into the visual web part project created above. Open the VisualWebPart1.ascx file and replace the date control and the label with the following:

<%@ Import Namespace="Microsoft.SharePoint.WebControls" %>

SharePoint:SPBoundField>

SharePoint:SPBoundField>

SharePoint:SPBoundField>

Columns>

SharePoint:SPGridView>

This adds a SharePoint data grid to the webpart. Now in the code behind replace the existing code with this:

SPLinqDataContext dc = new SPLinqDataContext(SPContext. Current.Web.Url);

EntityList Tasks = dc.GetList("Tasks");

var tQuery = from task in Tasks

select new

{

task.Title,

task.StartDate,

task.Body

};

spGridView.DataSource = tQuery;

spGridView.DataBind();

A custom visual Web part using LINQ to SharePoint to display data.

You will need to add reference to the Microsoft.SharePoint.Linq  assembly as well as add these using statements:

using Microsoft.SharePoint;

using Microsoft.SharePoint.Linq;

using System.Linq;

Build and deploy the Web Part. Add some items to the Tasks list and see that they appear in the Datagrid as well. You can also add the DateTimeControl back and modify the WebPart to query only for the selected tasks for that day.

As you can see, creating Web parts and query data from the SharePoint 2010 installation is very easy with the new Visual Web Part and LINQ to SharePoint features of VS2010.