by May 1, 2010 0 comments



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.

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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.

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.

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