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User1754860325 posted

I get the following error:

'DropDownList1' has a SelectedValue which is invalid because it does not exist in the list of items. Parameter name: value

aspx.cs code

MembershipUser currentUser = Membership.GetUser();
        Guid customerId = (Guid)currentUser.ProviderUserKey;
 
        DataTable dt = new DataTable();

 Page.DataBind(); 

        SqlConnection conn = new SqlConnection(@"Data Source=GMBOAT-PC\EMS_AFRICA;Integrated Security=True; User ID=xxxx; password=xxxx");
        SqlCommand sqlCmd = new SqlCommand("SELECT * FROM Staff WHERE Userid = @username", conn);
        SqlDataAdapter sqlDa = new SqlDataAdapter(sqlCmd);
 
        sqlCmd.Parameters.AddWithValue("@username", customerId);
        sqlDa.Fill(dt);
 
        if (dt.Rows.Count > 0)
        {
            TitleDropDownList.SelectedValue = dt.Rows[0]["Title"].ToString();
            txtSurname.Text = dt.Rows[0]["Firstname"].ToString();
            txtFirstname.Text = dt.Rows[0]["Surname"].ToString();
            txtIDNum.Text = dt.Rows[0]["IDNum"].ToString();
            DropDownList1.SelectedValue = dt.Rows[0]["ESSID"].ToString();
            txtStaffNum.Text = dt.Rows[0]["ESNumber"].ToString();
 
        }

In my aspx page I have a few dropdownlists and when ever I change one of the dropdowns it gives me the above 
error message.

Tuesday, July 30, 2013 6:30 PM

Answers

User1143442848 posted

I get the following error:

'DropDownList1' has a SelectedValue which is invalid because it does not exist in the list of items. Parameter name: value

Hi gmboat,

The reason of the error is that the value given to DropDownList1.SelectedValue is not in the ListItem of the DropDownList.

So please try to check the

TitleDropDownList.SelectedValue = dt.Rows[0]["Title"].ToString();

and

DropDownList1.SelectedValue = dt.Rows[0]["ESSID"].ToString();

Here is an example about how to set the SelectedValue and it works well in my local machine.

Code in .aspx

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
        <div>
            <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="true" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
                    </asp:DropDownList>           
        </div>
    </form>
</body>
</html>

code in .cs

protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                DropDownList ddlName =
                            (DropDownList)this.FindControl("DropDownList1");
                ddlName.Items.Add("1234");
                ddlName.Items.Add("Lisa");
                ddlName.Items.Add("Zhang");
                ddlName.SelectedValue = "1234";
            }
        }
             
        protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
        {
            DropDownList ddlName = (DropDownList)this.FindControl("DropDownList1");     
            ddlName.SelectedValue = "Zhang";                                 
        }

Best Regards,

Lisa Zhang

Marked as answer by Anonymous Thursday, October 7, 2021 12:00 AM

Thursday, August 1, 2013 4:07 AM

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User653228039 posted

Well, based on the wording of the error, I would assume that you are setting DropDownList1.SelectedValue to an invalid value because it doesn't exist in the list of items...

Possibly this line:

DropDownList1.SelectedValue = dt.Rows[0]["ESSID"].ToString();

Are you sure that the values you are getting from the ESSID column of that table are in the DropDownList1's list of items? Value, not Text...
Tuesday, July 30, 2013 6:39 PM
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User1754860325 posted

Yes I am sure. It gave no errors when I only had the top 2 rows of dropdowns and text boxes to display info of person who is loged in.

The rest of the page which I had done after testing the top 2 rows is for measurments of the user that I am working on now is now giving the error once I click on the save button.

Tuesday, July 30, 2013 6:43 PM
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User653228039 posted

Where do you populate the DropDownList with items? I know I used to have problems with getting their value (even though it appears you are trying to set its value) in events until I realized Page_Load executes before every event handler.

Tuesday, July 30, 2013 7:13 PM

User1143442848 posted

I get the following error:

'DropDownList1' has a SelectedValue which is invalid because it does not exist in the list of items. Parameter name: value

Hi gmboat,

The reason of the error is that the value given to DropDownList1.SelectedValue is not in the ListItem of the DropDownList.

So please try to check the

TitleDropDownList.SelectedValue = dt.Rows[0]["Title"].ToString();

and

DropDownList1.SelectedValue = dt.Rows[0]["ESSID"].ToString();

Here is an example about how to set the SelectedValue and it works well in my local machine.

Code in .aspx

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
        <div>
            <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="true" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
                    </asp:DropDownList>           
        </div>
    </form>
</body>
</html>

code in .cs

protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                DropDownList ddlName =
                            (DropDownList)this.FindControl("DropDownList1");
                ddlName.Items.Add("1234");
                ddlName.Items.Add("Lisa");
                ddlName.Items.Add("Zhang");
                ddlName.SelectedValue = "1234";
            }
        }
             
        protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
        {
            DropDownList ddlName = (DropDownList)this.FindControl("DropDownList1");     
            ddlName.SelectedValue = "Zhang";                                 
        }

Best Regards,

Lisa Zhang

Marked as answer by Anonymous Thursday, October 7, 2021 12:00 AM

Thursday, August 1, 2013 4:07 AM

User-1091252720 posted

This error occurs when you assign value to SelectedValue property which doen't exist either of value property of ListItems in DropDownList. In order to resolve this, I think that you should create static extension or any useful method to handle checking the existence. Here you can try static extension as following code:

public static void SetSelectedValue(this DropDownList dropDownList, string selectedValue)
{
	if (dropDownList != null)
	{
		var listItem = dropDownList.Items.FindByValue(selectedValue ?? String.Empty);
		if (listItem != null)
		{
			/*****************************************
			 * Should clear selection first to prevent error "Multple Selection" can occur
			 *****************************************/
			dropDownList.ClearSelection();
			listItem.Selected = true;
		}
	}
}

Then, use it in your code as follows:

if(dt.Rows[0]["Title"] != null)
{
    TitleDropDownList.SetSelectedValue(dt.Rows[0]["Title"].ToString());
}
if(dt.Rows[0]["ESSID"] != null)
{
    DropDownList1.SetSelectedValue(dt.Rows[0]["ESSID"].ToString());
}

Hope this will help you!!

Thursday, August 1, 2013 6:10 AM

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