Bind (Populate) DropDownList using business class with Linq in ASP.Net

Hi nauna,

Check this example. Now please take its reference and correct your code.

Database

For this example i have used of Northwind database that you can download using the link given below.

Download Northwind Database

HTML

<asp:DropDownList runat="server" ID="ddlCustomers">
</asp:DropDownList>
<asp:Button Text="Save" runat="server" OnClick="OnSave" />

DataAccess

C#

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

public class DataAccess
{
    public List<ListItem> GetCustomers(string country)
    {
        NorthwindEntities entities = new NorthwindEntities();
        List<ListItem> items = (from c in entities.Customers
                                orderby c.ContactName
                                where c.Country == country
                                select new ListItem
                                {
                                    Text = c.ContactName,
                                    Value = c.CustomerID
                                }).ToList();
        items.Insert(0, new ListItem { Text = "Select", Value = "0" });
        return items;
    }
}

VB.Net

Imports Microsoft.VisualBasic
Imports System.Collections.Generic
Imports System.Web.UI.WebControls
Imports NorthwindModel

Public Class DataAccess
    Public Function GetCustomers(ByVal country As String) As List(Of ListItem)
        Dim entities As NorthwindEntities = New NorthwindEntities()
        Dim items As List(Of ListItem) = (From c In entities.Customers
                                          Order By c.ContactName
                                          Where c.Country = country
                                            Select New ListItem _
                                            With {.Text = c.ContactName, .Value = c.CustomerID}).ToList()
        items.Insert(0, New ListItem With {.Text = "Select", .Value = "0"})
        Return items
    End Function
End Class

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        DataAccess da = new DataAccess();
        ddlCustomers.DataSource = da.GetCustomers("USA");
        ddlCustomers.DataTextField = "Text";
        ddlCustomers.DataValueField = "Value";
        ddlCustomers.DataBind();
    }
}
protected void OnSave(object sender, EventArgs e)
{
    string id = ddlCustomers.SelectedValue.Trim();
    string name = ddlCustomers.SelectedItem.Text.Trim();
    ClientScript.RegisterClientScriptBlock(this.GetType(), "", "alert('Name : " + name + "\\nId : " + id + "')", true);
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not IsPostBack Then
        Dim da As DataAccess = New DataAccess()
        ddlCustomers.DataSource = da.GetCustomers("USA")
        ddlCustomers.DataTextField = "Text"
        ddlCustomers.DataValueField = "Value"
        ddlCustomers.DataBind()
    End If
End Sub

Protected Sub OnSave(ByVal sender As Object, ByVal e As EventArgs)
    Dim id As String = ddlCustomers.SelectedValue.Trim()
    Dim name As String = ddlCustomers.SelectedItem.Text.Trim()
    ClientScript.RegisterClientScriptBlock(Me.GetType(), "", "alert('Name : " & name & "\nId : " & id & "')", True)
End Sub

Screenshot