asp.net dropdownlist doesn't accept text after databinding

Question

I have two dorpdownlists in my page. One is databound, and another has values added at the design time.

<asp:DropDownList ID="maritalStatus" runat="server" Width="180px">
        <asp:ListItem Value="-1">--SELECT--</asp:ListItem>
        <asp:ListItem>Single</asp:ListItem>
        <asp:ListItem>Divorced</asp:ListItem>
        <asp:ListItem>Married</asp:ListItem>
        <asp:ListItem>Widow(er)</asp:ListItem>
</asp:DropDownList>
<asp:DropDownList ID="country" runat="server" Width="180px">
</asp:DropDownList>

This is my Codebehind for filling the country dropDownList

using (SqlCommand com = new SqlCommand("SELECT CountryID,  CountryName FROM Country", con))
{
      SqlDataAdapter dad = new SqlDataAdapter(com);
      DataTable countryTab = new DataTable("Country");
      dad.Fill(countryTab);
      country.DataSource = countryTab;
      country.DataTextField = "CountryName";
      country.DataValueField = "CountryID";
      country.DataBind();
      country.Items.Insert(0, new ListItem("--SELECT--", "-1"));

}

But when I set "--SELECT--" to both dropDownLists, the maritalStatus dropDownList works fine; But, country dropdown shows this error

"'country' has a SelectedValue which is invalid because it does not exist in the list of items"

maritalStatus.Text = "--SELECT--";
country.Text = "--SELECT--";

If I set country Text as "-1", It will work fine. I don't understand why both dropDownLists are behaving in different way.

Did you look at this thread? http://stackoverflow.com/questions/14654220/has-a-selectedvalue-which-is-invalid-because-it-does-not-exist-in-the-list-of-it — demonplus, Apr 15 '15 at 10:53

Rahul Singh · Accepted Answer · 2015-04-15T11:02:25.583

Your problem is there is no Value like --SELECT-- in your dropdown therefore their is no match in the ListItem collection and hence the exception.

According to documentation of Dropdownlist Text property it:-

Gets or sets the SelectedValue property of the ListControl control.

Thus, when you are saying country.Text = "--SELECT--";, it is searching for a value of --SELECT-- which is not present in the collection but when you search for -1 it finds it and there is no exception.

Coming to the behavior difference in two dropdowns, it doesn't matter whether you bind it programmatically or declaratively both will behave the same and you will get the exception in both case.

Thanks :) I didn't get the exception for the first one. But it was not working. Now fixed... — Yesudass Moses, Apr 15 '15 at 11:22

score 1 · Answer 2 · answered Apr 15 '15 at 10:54

1

Just Replace

country.Items.Insert(0, new ListItem("--SELECT--", "-1"));

to

country.Items.Insert("0","--SELECT--");

this will solve issue

answered Apr 15 '15 at 10:54

sathish

71
6

score 0 · Answer 3 · answered Apr 15 '15 at 11:06

0

Just replace

country.Items.Insert(0, new ListItem("--SELECT--", "-1"));

To

country.Items.Insert(0, new ListItem("--SELECT--", "0"));

answered Apr 15 '15 at 11:06

Pradnya Bolli

1,915
1
19
37

asp.net dropdownlist doesn't accept text after databinding

3 Answers3