CODEWITHSUNDEEP
c#htmlasp.net
Rashid Abib
Rashid Abib

Reputation: 189

SelectedValue & SelectedItem From Drop Down List

I am attempting to write the selected values to two separate text boxes named this.txtTextSelected.Text = text; and this.txtValueSelected.Text = value;

My issue is that the values are not written to the two text boxes, and when an option is selected my page refreshes and doesn't actually store the selected value which makes me think
1) Either my HTML for the drop down list is incorrect
2) I have added un-needed syntax for something
But I am scratching my head as to what the real deal is.

This is my HTML for the drop down list

<asp:DropDownList ID="dropdownlist1" CssClass="DropDownLists" 
runat="server" Width="90px"
AutoPostBack="true" 
OnSelectedIndexChanged="dropdownlist1_SelectedIndexChanged">
</asp:DropDownList>



And this is my C# code behind for the page

protected void dropdownlist1_SelectedIndexChanged(object sender, EventArgs e)
{
    string value = dropdownlist1.SelectedValue;
    string text = dropdownlist1.SelectedItem.Text;
    this.txtValueSelected.Text = value;
    this.txtTextSelected.Text = text;
}



EDIT Will this remedy my problem (basing this off @David comment below)

if (!IsPostBack)
{
    BindDropDownList();
}

Upvotes: 0

Views: 81

Answers (1)

David
David

Reputation: 218960

(In response to comments and the question edit...)

Unlike WinForms, WebForms "form" objects don't persist in memory. Web applications are designed to be inherently stateless. So every request results in re-instantiating the targeted form object, which invokes all of the start-up stuff that happens in a form.

This includes Page_Load.

So any time you click a button or do anything that involves posting the page back to the server, Page_Load (and other initialization events) happen again, before any event handlers or custom logic.

This means that if you're binding your controls in Page_Load, you're going to re-bind them before you try to use them. In WebForms, the standard fix for this is to wrap them in a conditional when binding:

if (!IsPostBack)
{
    // bind your controls
}

This will bind the controls when initially loading a page, but not when re-submitting the page's form to the page (posting back).

Upvotes: 1

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