'DropDownList1' has a SelectedValue which is invalid because it does not exist in the list of items

Question

User-1907931422 posted

Hello, I know that this is a notorious issue and there are many disscussion online but they are not fit for my case. Therefore I open this thread, hopefully I can get an advice.

I have a dropdown list

 <asp:DropDownList ID="DropDownList1" runat="server" AppendDataBoundItems="true">
          </asp:DropDownList>

In the code behind, I filled the dataset as below:

cmd.CommandText = "SELECT [FirstName], [LastName], [Degree], [Organization], [Phone],[Ext]  FROM [User_ExtraInfo] WHERE [UserID] = @UserID";
                string UserID = user.ProviderUserKey.ToString();
                cmd.Parameters.Add("@UserID", SqlDbType.VarChar).Value = UserID;
                DataTable dt = new DataTable();

                using (SqlDataAdapter da = new SqlDataAdapter(cmd))
                {
                    da.Fill(dt);
                }
 if (dt.Rows[0]["Organization"].ToString() == null || dt.Rows[0]["Organization"].ToString() == "")
                    DropDownList1.SelectedValue = "Please Select";
                else
                DropDownList1.SelectedValue = dt.Rows[0]["Organization"].ToString();

When I stepped through the code, I found the value of dt.Rows[0]["Organization"].ToString() is not null or empty but DropDownList1.SelectedValue is null.

Finally I got an error:

'DropDownList1' has a SelectedValue which is invalid because it does not exist in the list of items

Thanks.

Answer 1

User2053451246 posted

You are trying to set it to "Please Select" but you don't have that as a choice on the list.  Change your ddl code to this:

<asp:DropDownList ID="DropDownList1" runat="server" AppendDataBoundItems="true">
<asp:ListItem>Please Select</asp:ListItem>
 </asp:DropDownList>

Answer 2

User1459882081 posted

Could you show us some more code? Like how you fill your ddl?

Answer 3

User-1907931422 posted

You are right, but I want to assign  dt.Rows[0]["Organization"].ToString() to DropDownList1.SelectedValue directly why no lucky?

I added

<asp:ListItem>Please Select</asp:ListItem>

Now only one item "Please Select" in the dropdown menu.

More code:

SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["MembershipDB"].ConnectionString);
                con.Open();
                SqlCommand cmd = new SqlCommand();
                cmd.Connection = con;
                cmd.CommandText = "SELECT [FirstName], [LastName], [Degree], [Organization], [Phone],[Ext]  FROM [User_ExtraInfo] WHERE [UserID] = @UserID";
                string UserID = user.ProviderUserKey.ToString();
                cmd.Parameters.Add("@UserID", SqlDbType.VarChar).Value = UserID;
                DataTable dt = new DataTable();

                using (SqlDataAdapter da = new SqlDataAdapter(cmd))
                {
                    da.Fill(dt);
                }

                TextFirstName.Text = dt.Rows[0]["FirstName"].ToString();
                TextLastName.Text = dt.Rows[0]["LastName"].ToString();
                TextDegree.Text = dt.Rows[0]["Degree"].ToString();
                if (dt.Rows[0]["Organization"].ToString() == null || dt.Rows[0]["Organization"].ToString() == "")
                    DropDownList1.SelectedValue = "Please Select";
                else
                DropDownList1.SelectedValue = dt.Rows[0]["Organization"].ToString();
                TextPhone.Text = dt.Rows[0]["Phone"].ToString();
                TextExt.Text = dt.Rows[0]["Ext"].ToString();

 

Answer 4

User1459882081 posted

You can only select the value that already is existing in the ddl. First make sure how you populate the ddl and it has the value you want to select.

Answer 5

User2053451246 posted

else
DropDownList1.Items.Add(dt.Rows[0]["Organization"].ToString())  <-- add this line
DropDownList1.SelectedValue = dt.Rows[0]["Organization"].ToString();

Answer 6

User1459882081 posted

Is it working now?

Answer 7

User-1907931422 posted

It works out, let me double check.

Answer 8

User-1907931422 posted

It only add the first row, how can I add all rows? I removed where clause in the command.

In my code I used Rows[0], there are other rows such as Rows[1], Rows[2]....etc.

Answer 9

User1459882081 posted

Ideally you should use this...

ddl.Items.Clear();
ddl.Items.Add(new ListItem("<Select an item>", "-1"));
ddl.AppendDataBoundItems = true;
ddl.DataSource = //Assign your datatable here            

ddl.DataTextField = "What you want to display in ddl";
ddl.DataValueField = "ID for the item";
ddl.DataBind();

Answer 10

User2053451246 posted

Put inside a loop:

DataRow dr = null;
foreach (DataRow dr in dt.Rows()) {
	DropDownList1.Items.Add(dr["Organization"].ToString());
}


I'm a VB programmer.  Hopefully my code converted to C# correctly for you. :)

Answer 11

User-1907931422 posted

I mean that can I use foreach? But how to extract the specific column?

foreach(item in dt.Rows)
{
       DropDownList1.Items.Add(item)
}

Answer 12

User1459882081 posted

Like...

item["Organization"].ToString(); 

But ideally you should not need to use loop.