Select Data - Eager Loading

Vijay Prativadi
11y
2.9k
0
0
100
Article

Introduction

This working demonstrates an interesting and very useful concept in Entity Framework.

Question: What is eager loading?

In simple terms "when the loop is started, each of the objects that you have specified will be pulled from the database and built into a gigantic in-memory data structure. This will be a very expensive operation, pulling an enormous amount of data from your database. However, it will all happen in one database round trip, with a single SQL query execution".

Step 1: Create a new web application

Step 2: Adding a new Entity Data Model Framework

Step 3: The complete code of WebForm1.aspx is as in the following:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="SelectDataEagerLoadingApp.WebForm1" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
     <title></title>
</head>
<body>
     <form id="form1" runat="server">
         <div>
             <center>
                 <div>
                     <table>
                         <tr>
                             <td colspan="2" align="center">
                                 <asp:Label ID="Label1" runat="server" Text="Select Data - Eager Loading" Font-Bold="true" Font-Size="Large" Font-Names="Verdana"
ForeColor="Maroon"></asp:Label></td>
                         </tr>
                         <tr>
                             <td colspan="2" align="center">
                                 <asp:Button ID="Button1" runat="server" Text="Select Data" Font-Names="Verdana" Width="213px" BackColor="Orange" Font-Bold="True" OnClick="Button1_Click"
/></td>
                         </tr>
                         <tr>
                             <td colspan="2" align="center">
                                 <asp:GridView ID="GridView1" runat="server" CssClass="grid" BackColor="LightGoldenrodYellow" BorderColor="Tan" BorderWidth="1px" CellPadding="2"
ForeColor="Black" GridLines="None">
                                     <AlternatingRowStyle BackColor="PaleGoldenrod" />
                                     <FooterStyle BackColor="Tan" />
                                     <HeaderStyle BackColor="Tan" Font-Bold="True" />
                                     <PagerStyle BackColor="PaleGoldenrod" ForeColor="DarkSlateBlue" HorizontalAlign="Center" />
                                     <SelectedRowStyle BackColor="DarkSlateBlue" ForeColor="GhostWhite" />
                                     <SortedAscendingCellStyle BackColor="#FAFAE7" />
                                     <SortedAscendingHeaderStyle BackColor="#DAC09E" />
                                     <SortedDescendingCellStyle BackColor="#E1DB9C" />
                                     <SortedDescendingHeaderStyle BackColor="#C2A47B" />
                                     <EmptyDataTemplate>No Records Found!</EmptyDataTemplate>
                                 </asp:GridView>
                             </td>
                         </tr>
                     </table>
                 </div>
             </center>
         </div>
     </form>
</body>
</html>

Step 4: The complete code of WebForm1.aspx.cs is as in the following:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace SelectDataEagerLoadingApp
{
     public partial class WebForm1 : System.Web.UI.Page
     {
         protected void Page_Load(object sender, EventArgs e) { }
         protected void Button1_Click(object sender, EventArgs e)
         {
             using (CompanyEntities objEntities = new CompanyEntities())
             {
                 objEntities.ContextOptions.LazyLoadingEnabled = false;
                 GridView1.DataSource = objEntities.tblEmployee.Take(15).ToList();
                 GridView1.DataBind();
             }
         }
     }
}

Step 5: The output of the application is as in the following:

Step 6: The select data output of the application is as in the following:

I hope this working was useful for you. I look forward for your comments and feedback. Thanks Vijay.

Up Next

Ebook Download

View all

The SOLID Principles

Read by 7.1k people

Download Now!

Learn

View all

MVC Corporation

MVC Corporation is consulting and IT services based company.