Delete Data - DbContext Generator Template

Vijay Prativadi
12y
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Article

Introduction

This article demonstrates one of the interesting and very useful concepts in Entity Framework.

Question: What is DbContext Generator?

In simple terms "It enables code to be generated with a template based upon an Entity".

Step 1: Create a new web application

Step 2: Adding New Entity Data Model Framework

Step 3: Add a new DbContext template

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

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="DbContextDeleteData.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">
    <center>
        <div>
            <table>
                <tr>
                    <td colspan="2" align="center">
                        <asp:Label ID="Label1" runat="server" Text="Delete Data - DbContext Template" Font-Bold="true"
                            Font-Size="Large" Font-Names="Verdana" ForeColor="Maroon"></asp:Label>
                    </td>
                </tr>
                <tr>
                    <td>
                        <asp:Label ID="Label2" runat="server" Text="Please Enter Employee Id" ForeColor="Brown"
                            Font-Bold="true" Font-Size="Medium" Font-Names="Verdana"></asp:Label>
                    </td>
                    <td>
                        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
                    </td>
                </tr>
                <tr>
                    <td colspan="2" align="center">
                        <asp:Button ID="Button1" runat="server" Text="Delete Data" Font-Names="Verdana" Width="213px"
                            BackColor="Orange" Font-Bold="True" OnClick="Button1_Click" />
                    </td>
                </tr>
                <tr>
                    <td colspan="2" align="center">
                        <asp:Label ID="Label3" runat="server" Font-Bold="true" Font-Size="Medium" Font-Names="Verdana"></asp:Label>
                    </td>
                </tr>
            </table>
        </div>
    </center>
    </form>
</body>
</html>

Step 5: The complete code of WebForm1.aspx.cs looks 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 DbContextDeleteData

{

public partial class WebForm1 : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

}

protected void Button1_Click(object sender, EventArgs e)

{

if (string.IsNullOrEmpty(TextBox1.Text))

{

Label3.Text = "Please Enter Some Values";

Label3.ForeColor = System.Drawing.Color.Red;

}

else

{

int id = int.Parse(TextBox1.Text);

var query = (from r in objEntities.tblEmployee where r.EmpId == id select r).Single();objEntities.tblEmployee.Remove(query);

objEntities.SaveChanges();

Label3.Text = "Data Deleted Successfully";

Label3.ForeColor = System.Drawing.Color.Green;

TextBox1.Text = string.Empty;

}

#region Instance MembersCompanyEntities objEntities = new CompanyEntities();

#endregion}

}

Step 6: The output of the application looks as in the following:

Step 7: The deleted data output of the application looks as in the following:

I hope this article was useful for you.