How to fix "ddlclass" has a selectedvalue which is invalid because it does not exist in the list of items dropdownlist

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I have gridview class and I am trying to display student with their marks.
But when I do I am getting the error -  "ddlclass" has a selectedvalue which is invalid because it does not exist in the list of items dropdownlist.

Class.aspx
<asp:GridView ID="Gridviewclass" runat="server" >
      <Columns>
            <asp:TemplateField HeaderText="Myclass">
                <ItemTemplate>
                    <asp:DropDownList ID="ddlclass" runat="server" DataTextField="Name" DataValueField="classID"
SelectedValue='<%# Bind("classID") %>' >
                    </asp:DropDownList>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Marks" SortExpression="Marks">
                <ItemTemplate>
                    <asp:TextBox ID="txtMarks" runat="server" Text='<%# Bind("Marks") %>' ></asp:TextBox>
                </ItemTemplate>
            </asp:TemplateField>
        </Columns>
    </asp:GridView>



Class.aspx.cs
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
 Gridviewclass.DataSource = mainclass
            Gridviewclass.DataBind()
End Sub

Posted 8-Sep-15 7:10am

apr1234

Updated 8-Sep-15 7:19am

v2

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F-ES Sitecore 8-Sep-15 13:17pm

That happens when you give a dropdown a SelectedValue that does not match anything it has in its Items collection. Can't say what the issue is from what you've posted though. Would need to post where you set the selected value, how your dropdowns are populated, what you mean by "dynamically" etc.

apr1234 8-Sep-15 14:00pm

Updated code:

Class.aspx
<asp:GridView ID="Gridviewclass" runat="server" >
<columns>
<asp:TemplateField HeaderText="Myclass">
<itemtemplate>
<asp:DropDownList ID="ddlclass" runat="server" DataTextField="Name" DataValueField="classID" DataSource='<%# dtclass %>'
SelectedValue='<%# Bind("classID") %>' >

<asp:TemplateField HeaderText="Marks" SortExpression="Marks">
<itemtemplate>
<asp:TextBox ID="txtMarks" runat="server" Text='<%# Bind("Marks") %>' >

Class.aspx.cs

Public dtclass As New DataTable
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
GetclassDataTable()
Gridviewclass.DataSource = mainclass
Gridviewclass.DataBind()
End Sub

Private Function GetclassDataTable() As DataTable

If Cache.Item("class") Is Nothing Then
dtclass.Columns.Add(New DataColumn("Name"))
dtclass.Columns.Add(New DataColumn("ID"))
dtclass = classes.Getclass()
Return dtAttorneys
Else
Return DirectCast(Cache.Item("class"), DataTable)
End If

End Function

2 solutions

Solution 2

I think you must be binding the dropdownlist inside the GridView rowdatabound event.

Now you just need to check if the classid for the row is present as a value of the dropdownlist. Seems like for some row the classid is not matching in the list of drop down values.

Posted 8-Sep-15 8:37am

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ)

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Manas_Kumar · Accepted Answer · 2015-09-08T07:49:00

You are getting error because no listitem is not set in dropdown when a selected value is set. So in below code I added demo ListItem in dropdown control(you can change it as per your requirement).

XML

<asp:GridView ID="Gridviewclass" runat="server" >
      <Columns>
            <asp:TemplateField HeaderText="Myclass">
                <ItemTemplate>
                    <asp:DropDownList ID="ddlclass" runat="server" DataTextField="Name" DataValueField="classID"
SelectedValue='<%# Bind("classID") %>' >
                        <asp:ListItem>1</asp:ListItem>
                        <asp:ListItem>2</asp:ListItem>
                        <asp:ListItem>3</asp:ListItem>
                        <asp:ListItem>4</asp:ListItem>
                    </asp:DropDownList>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Marks" SortExpression="Marks">
                <ItemTemplate>
                    <asp:TextBox ID="txtMarks" runat="server" Text='<%# Bind("Marks") %>' ></asp:TextBox>
                </ItemTemplate>
            </asp:TemplateField>
        </Columns>
    </asp:GridView>

Note: If you want to bind data to dropdown from database then you need to use OnRowDataBound property of gridview. Please use below link for reference.

http://www.aspsnippets.com/Articles/How-to-populate-DropDownList-in-GridView-in-ASPNet.aspx[^]