ASP .NET Dropdown not reflecting SelectedItem-CodePudding

I have an Asp:DropDownList like this:

                    <asp:DropDownList runat="server" ID="ReinsurerInput">
                    </asp:DropDownList>

Filled like this:

                'Fill dropdowns
                If dsReinsurers.Tables("Reinsurers").Rows.Count > 0 Then
                    For Each dr As DataRow In dsReinsurers.Tables("Reinsurers").Rows
                        ReinsurerInput.DataSource = dsReinsurers.Tables("Reinsurers")
                        ReinsurerInput.DataTextField = "ReinsurerName"
                        ReinsurerInput.DataValueField = "ReinsurerId"
                        ReinsurerInput.DataBind()
                    Next
                End If

Here is my dropdown: https://ibb.co/h9J4ssb

Here is the input object on the backend: https://ibb.co/ysd93t4

How do I make the object on the backend match what the view is doing?

CodePudding user response：

What does the page load event look like that loads up the dropdown list?

You need this in 99% of use cases this:

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

    If Not IsPostBack Then

        LoadGrid
        LoadCombo

    End If

End Sub

in other words, loading up of data like a gridview, or dropdown list?

You need to ONLY load it on the first REAL page load (IsPostBack = false).

If you don't do the above, then on any button click or anything that triggers a post-back (which is quite much every event stub), then re-loading the dropdown list each time means the users' selection each time will be re-set and lost.

so, ONLY load up the data on first page load. it also means of course your page will load faster/better, since you not re-pulling the data again each time a user clicks on some button or whatever.

So, keep in mind that page load will trigger each time a button or whatever is clicked on that page. and if this happens to be code that needs/wants/gets the dropdown list, then of course you can't (don't want) the code to load up the dropdown list to re-run each time, since as noted, it will re-set the selection made.

It possible that you already have the "correct" if/then block with a test for isPostback as per above, but , if not, then place your "loading data" code inside of that page load if not is postback block.