Bind Asp.Net DropDownList and Disable or make some items Unselectable based on Some condition

Introduction:

Sometime it is required to fill dropdown and disable its some of the items on the basis of some condtion. While working on one of my asp.net project I got the requirement to populate departments in DropDownList and disable some of them so that they can't be selected.

Suppose if Department Name is “HRM” then it got disable.

In this article, I have explained how to dynamically Fill Dropdown List from SQL
Server Database table and how to disable or making some items non-selectable based on condition.

Create a table in the SQL server database with the columns names and data type as shown below and name it "Dept_Master"

Columns Name	Data Type
Dept_Id_Pk	Int(Primary Key. Auto Increment)
Dept_Name	varchar(100)

And insert some department names in this table. 

Now In the Web.config file create the connection string as:

<connectionStrings>

 <add name="Empcon" connectionString="Data Source=localhost;Initial Catalog=test;Integrated Security=True"/>

 </connectionStrings>

• In the default. aspx page place a DropDownList controls as:

<fieldset style="width: 270px;">

            <legend>Fill DropDownList and Disable Items</legend>

            <asp:DropDownList ID="ddlDepartments" runat="server">

            </asp:DropDownList>

        </fieldset>

Asp.Net C# Code to Fill  DropDownList and Disable specified items

Include required namespaces

using System.Data;

using System.Data.SqlClient;

using System.Configuration;

Then write the code as:

    protected void Page_Load(object sender, EventArgs e)

    {

        if (!Page.IsPostBack)

        {

            FillDropDownListAndDisableItems();

        }

    }

    protected void FillDropDownListAndDisableItems()

    {

        SqlCommand cmd = new SqlCommand();

        SqlConnection con = new SqlConnection();

        SqlDataReader dr = null;

        try

        {

            con = new SqlConnection(ConfigurationManager.ConnectionStrings["Empcon"].ConnectionString);

            cmd = new SqlCommand("Select * from Dept_Table", con);

            if (con.State==ConnectionState.Closed)

            {

             con.Open();

            }           

            dr = cmd.ExecuteReader();

            if (dr.HasRows)

            {

                ddlDepartments.DataSource = dr;

                ddlDepartments.DataTextField = "Dept_Name";

                ddlDepartments.DataValueField = "Dept_Id_pk";

                ddlDepartments.DataBind();

                ddlDepartments.Items.Insert(0, new ListItem("--Select Department--", "-1"));      

                //Disable dropdownlist items based on condition

                foreach (ListItem item in ddlDepartments.Items)

                {

                    //Check by item value

                    //if (item.Value == "2" || item.Value == "4")

                    //OR Check by item text

                    if (item.Text == "HRM" || item.Text == "Test")

                    {

                        item.Attributes.Add("disabled", "disabled");

                    }

                }

            }

            else

            {

                ddlDepartments.Items.Insert(0, "--No Departments--");

            }

        }

        catch (Exception ex)

        {

            Response.Write(“Error occured:" + ex.Message.ToString());

        }

        finally

        {           

            con.Close();          

            cmd.Dispose();

            dr.Dispose();

        }

    }

Asp.Net VB Code to Fill/Bind/populate DropDownList and Disable specified items

Include required namespaces

Imports System.Data

Imports System.Data.SqlClient

Imports System.Configuration

Write the code as:

    Protected Sub Page_Load(sender As Object, e As System.EventArgs) Handles Me.Load

        If Not Page.IsPostBack Then

            FillDropDownListAndDisableItems()

        End If

    End Sub

    Protected Sub FillDropDownListAndDisableItems()

        Dim cmd As New SqlCommand()

        Dim con As New SqlConnection()

        Dim dr As SqlDataReader = Nothing

        Try

            con = New SqlConnection(ConfigurationManager.ConnectionStrings("EmpCon").ConnectionString)

            cmd = New SqlCommand("Select * from Dept_Table", con)

            If con.State = ConnectionState.Closed Then

                con.Open()

            End If

            dr = cmd.ExecuteReader()

            If dr.HasRows Then

                ddlDepartments.DataSource = dr

                ddlDepartments.DataTextField = "Dept_Name"

                ddlDepartments.DataValueField = "Dept_Id_pk"

                ddlDepartments.DataBind()

                ddlDepartments.Items.Insert(0, New ListItem("--Select Department--", "-1"))

                'Disable dropdownlist items based on condition

                For Each item As ListItem In ddlDepartments.Items

                    'Check by item value

                    'if (item.Value == "2" || item.Value == "4")

                    'OR Check by item text

                    If item.Text = "HRM" OrElse item.Text = "Testing" Then

                        item.Attributes.Add("disabled", "disabled")

                    End If

                Next

            Else

                ddlDepartments.Items.Insert(0, "--No Departments--")

            End If

        Catch ex As Exception

            Response.Write("Error occured:" & ex.Message.ToString())

        Finally

            con.Close()

            cmd.Dispose()

            dr.Dispose()

        End Try

    End Sub