DropDownList:
The DropDownList is one of my favorite contols. It takes up a small space on your
page and allows the user to select from a list of items. You can either hand-type
this list in manually or you can create a DataSource of information and then "bind"
the control to the DataSource. (Choose from Access Database,
SQL Database, XML file, etc. then Select a DataField to display then Select a Value
for the Data)
How to detect which item was selected from the dropdownlist
When you have many controls on a page, you may not want to get the selected
answer immediately but instead wait until a submit button is clicked. In this
scenerio, you add the code to the button event. But when you do want an
immediate answer, add AutoPostBack="True" to the dropdownlist See the results of
this in the dropdown list shown here:
This ddl was created using the Edit Items:
ASP.NET
<asp:dropdownlist id="ddlFruitList" runat="server" AutoPostBack="true" />
VB.NET
Protected Sub ddlFruit_SelectedIndexChanged(ByVal sender As Object,
ByVal e As System.EventArgs) Handles ddlFruit.SelectedIndexChanged
Dim YourFruit As String = ddlFruitList.SelectedValue
lblFruit.Text = "You picked " + YourFruit
End Sub
<asp:dropdownlist id="ddlFruitList" runat="server" AutoPostBack="true" />
Build your DropDownList
You have several options for adding the text into the dropdownlist properties.
Listed below are just 3 of the many options you have available.
OPTION 1: Type the name for each list item directly
into the dropdownlist in your ASP.NET web page.
<asp:dropdownlist id="myFirstList" runat="server" />
OPTION 2: Type the list in code-behind (VB.NET or C#)
using an array
DropDownList1.Items.Clear()
Dim months() As String {"January","February","March","April","May","June",
"July", "August", "September", "October", "November", "December"}
DropDownList1.DataSource = months
DropDownList1.DataBind()
OPTION 3: Get your list from a datasource (ie.
database, etc.) and bind it to a DataSource control.
<asp:dropdownlist id="myFirstList" runat="server"
DataSourceId="srcMovies" DataTextField="Title" />
<asp:SqlDataSource id=srcMovies" ConnectionString="Data Source=.\SQLExpress;
AttachDbFilename=|DataDirectory| MyMovieDatabase.mdf;
Integrated Security=True; User Instance=True"
SelectCommand="SELECT Title FROM Movies" runat="server" />
*Notice the ID of the SqlDataSource is the same as the DataSourceId of the
dropdownlist.