Create a new page called Step1.aspx. Within the .aspx page
add a GridView control like so:
Listing 2
<%@ Page Language="C#" CodeFile="Step1.aspx.cs" Inherits="Step1" %>
<html>
<body>
<form id="form1"runat="server">
<div>
<h1>City Names</h1>
<asp:GridView ID="GridView1" runat="server">
</asp:GridView>
</div>
</form>
</body>
</html>
Within the code-behind file we’ll then write the canonical
“hello world” LINQ sample – which involves searching and ordering a list of
strings:
Listing 3
using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Query;
public partial class Step1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
string[] cities = { "London", "Amsterdam", "San Francisco", "Las Vegas",
"Boston", "Raleigh", "Chicago", "Charlestown",
"Helsinki", "Nice", "Dublin" };
GridView1.DataSource = from city in cities
where city.Length > 4
orderby city
select city.ToUpper();
GridView1.DataBind();
}
}In the above sample I’ve created an array of strings listing
the cities I’ve visited from Jan->May of this year. I’m then using a LINQ
query expression against the array. This query expression returns all cities
where the city name is greater than 4 characters, and orders the result in
alphabetical order and transforms those city names into upper case.
LINQ queries return results of type: IEnumerable<T> --
where <T> is determined by the object type of the “select” clause. In
the above sample “city” is a string, so the type-safe result is a generics
based collection like so:
Listing 4
IEnumerable<string> result = from city in cities
where city.Length > 4
orderby city
select city.ToUpper();
Because ASP.NET controls already support databinding to any
IEnumerable collection, we can easily assign this LINQ query result to the
GridView and call its DataBind() method to generate this page output result:
Figure 3
<img border=0 width=204 height=473src="/ArticleFiles/922/image003.jpg">
Note that instead of using the GridView control I could have
just as easily used the <asp:repeater>, <asp:datalist>,
<asp:dropdownlist>, or any other ASP.NET list control (both those
built-into the product or ones built by other developers). For the purposes of
these samples I’m just going to use the <asp:gridview> -- but again know
that you can use any.
