DotNet Tutorial: Bind DropDownList using simple user defined method in ASP.Net

Introduction:

In this article i will explain how to bind DropDownList using simple user defined method in ASP.Net.

Objective:

Bind DropDownList using simple user defined method in ASP.Net
User defined method should accept collection (e.g: List<Student> or List<Department> or List<User> or List<Role> etc)
User defined method should accept DataTable as well.

In this article i created a class called Student.cs as shown below:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

public class Student
{
public int StudentID { get; set; }
public string StudentName { get; set; }

public static List<Student> GetStudents()
{
var lstStudent = new List<Student>{
new Student { StudentID = 1, StudentName = "Aditya Rao" },
new Student { StudentID = 2, StudentName = "Utpal Lade" },
new Student { StudentID = 3, StudentName = "Aditya Utpal" }
};
return lstStudent;
}
}

I created a class called Deptment.cs as shown below:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

public class Deptment
{
public int DeptmentID { get; set; }
public string DeptmentName { get; set; }

public static List<Deptment> GetDeptments()
{
var lstDeptment = new List<Deptment>{
new Deptment { DeptmentID = 1, DeptmentName = "MCA" },
new Deptment { DeptmentID = 2, DeptmentName = "MBA" },
new Deptment { DeptmentID = 3, DeptmentName = "BCA" }
};
return lstDeptment;
}
}

DropDownListDemo.aspx:-

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="dopdownlistdemostaticdata.aspx.cs" Inherits="dopdownlistdemostaticdata" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div align="center">
Department <asp:DropDownList ID="ddlDeptment" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ddlDeptment_SelectedIndexChanged"></asp:DropDownList><br/>

Student<asp:DropDownList ID="ddlStudent" runat="server"></asp:DropDownList>
</div>
</form>
</body>
</html>

DropDownListDemo.aspx.cs:-

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class dopdownlistdemostaticdata : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
CommonUI.FillDropDown(ddlDeptment, Deptment.GetDeptments(), "DeptmentName", "DeptmentID");

}
}
public class CommonUI
{

public static void FillDropDown<T>(DropDownList dropDownList, List<T> list, string DataTextField, string DataValueField)
{
if (list != null && list.Count > 0)
{
dropDownList.DataSource = list;
dropDownList.DataTextField = DataTextField;
dropDownList.DataValueField = DataValueField;
dropDownList.DataBind();
}
// Insert 'Select' option at '0' index.
dropDownList.Items.Insert(0, (new ListItem("Select", "-1")));
}
}
protected void ddlDeptment_SelectedIndexChanged(object sender, EventArgs e)
{
int ddl = ddlDeptment.SelectedIndex;
if (ddl == 1)
{
CommonUI.FillDropDown(ddlStudent, Student.GetStudents(), "StudentName", "StudentID");
}

}

}

FillDropDown method accepts 4 parameters:

dropDownList - DropDownList ID for which you are binding
list - It may be List<Student> or List<Department>, List<User>, List<Role>, etc.
dataTextField - Gets or sets the field of the data source that provides the text content of the list items.
dataValueField - Gets or sets the field of the data source that provides the value of each list item

Output:-

DotNet Tutorial

Bind DropDownList using simple user defined method in ASP.Net

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