Change binding of dropdown list based on another dropdownlist

Question

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I have 2 drop-down lists. One is populated manually. The other I would like to bind to a different table depending on the value selected in the first.

VB

Protected Sub ContactType_SelectedIndexChanged(sender As Object, e As System.EventArgs) Handles ContactType.SelectedIndexChanged
    Dim dc As New DataClassesDataContext()
    If ContactType.SelectedItem.Text = "Company" Then
        ContactRelationship.DataSource = dc.CompanyTypes
        ContactRelationship.DataTextField = "CompanyType"
        ContactRelationship.DataValueField = "CompanyTypeID"
        ContactRelationship.DataBind()
    ElseIf ContactType.SelectedItem.Text = "Employee" Then
        ContactRelationship.DataSource = dc.EmployeeTypes
        ContactRelationship.DataTextField = "EmployeeType"
        ContactRelationship.DataValueField = "EmployeeTypeID"
        ContactRelationship.DataBind()
    End If
End Sub

<asp:DropDownList ID="ContactType" runat="server" Width="200px" AutoPostBack="True">
<asp:ListItem Text="Company">
<asp:ListItem Text="Employee">
<asp:ListItem Text="Emergency Contact">
<asp:ListItem Text="Associates">

<asp:DropDownList ID="ContactRelationship" runat="server" Width="200px">

I know the code is barbaric, I'll clean it up after I find the solution.
I'm using asp.net 4.0, Linq to SQL, and Sql Server express 2008r2.

I'm getting an error after I try to change value in ddl1. It seem to me that ddl2 will not bind to another table until it is somehow unbound?

All I really need is a push in the right direction. Thank you for your help.

Posted 9-Sep-11 12:32pm

jfclark27

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hitech_s 10-Sep-11 1:13am

my suggestion is put your dropdownlists inside update panels it will help u

2 solutions

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srinivas vadepally · Answer 1 · 2011-09-10T00:19:00

Solution 1

Hi jfclrak27,
Go through the following link,
Click me[^]

Posted 10-Sep-11 0:19am

srinivas vadepally

jfclark27 · Answer 2 · 2011-09-10T05:37:00

I will look into that. Thank you. I worked on problem last night and came up with an alternate solution. I realized I didn't really need to bind ddl to table, just use linq to read it into a data set then bind to that.

If ContactType.SelectedItem.Text = "Company" Then
         Dim Types = From t In dc.CompanyTypes
             Select t.CompanyType
         ContactRelationship.DataSource = Types
         ContactRelationship.DataBind()

This is working great for me. Don't know why I got all wrapped around the axle trying to reinvent the wheel. I'm working on designing a wizard in a web app.