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8.0

DropDownList Databinding Problem

Asked by mcourt in Programming for ASP.NET, Visual Studio

Tags: ASP.NET, Visual Studio

I have a problem databinding a DropDownList to my GridView, I can Bind the data from one table (Using Stored Procedures) and present this in the required cell of the Gridview results. My problem is when I use edit and then update the value, I receive "Object reference not set to an instance of an object" runtime error. Code is in C# behind and I cannot figure out a way of binding the DropDownList to the Gridview data row, at least I think that is the problem.
Code as follows:

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             <asp:GridView ID="GridViewOwners" runat="server" AutoGenerateColumns="False" 
                AllowPaging="true" PageSize="2" CssClass="adgridtablestyle2" 
                OnPageIndexChanging="GridViewOwners_PageIndexChanging" DataKeyNames="DiagramID" 
                AutoGenerateEditButton="True" OnRowEditing="GridViewOwners_RowEditing" 
                OnRowCancelingEdit="GridViewOwners_RowCancelingEdit" OnRowUpdating="GridViewOwners_RowUpdating"
                 OnRowDataBound="bindDropOwners">
                <EditRowStyle BackColor="#F7F7F7" />
                <AlternatingRowStyle CssClass="adgridaltrowstyle2" />
                <HeaderStyle CssClass="adgridheaderstyle2" />
                <RowStyle CssClass="adgridrowstyle2" />
                <PagerStyle CssClass="pagerStyle" />
                <Columns>
                    <asp:TemplateField>
                        <HeaderTemplate>
                            <asp:Label ID="hdrDiagramID" runat="server" Visible="True" Text="Diagram ID"></asp:Label>
                        </HeaderTemplate>
                        <ItemTemplate>
                            <asp:Label ID="lblDiagramID" runat="server" Visible="True" Text='<%# Eval("DiagramID") %>'></asp:Label>
                        </ItemTemplate>
                    </asp:TemplateField>
                    <asp:TemplateField>
                        <HeaderTemplate>
                            <asp:Label ID="lblDiagramOwnerHeader" runat="server" Visible="True" Text="Diagram Owner"></asp:Label>
                        </HeaderTemplate>
                        <ItemTemplate>
                            <asp:Label ID="lblDiagramOwner" runat="server" Visible="True" Text='<%# Eval("Username") %>'></asp:Label>
                        </ItemTemplate>
                        <EditItemTemplate>
                            <asp:Label ID="lblDiagramOwner" runat="server" Visible="True" Text='<%# Eval("Createdby") %>'></asp:Label>
                            <asp:DropDownList ID="drpDiagramOwner" runat="server" AutoPostBack="true" 
                                AppendDataBoundItems="true" 
                                onselectedindexchanged="drpDiagramOwner_SelectedIndexChanged">
                            </asp:DropDownList>
                        </EditItemTemplate>
                    </asp:TemplateField>
                </Columns>
            </asp:GridView>
 
 
//Code Behind C#
 
    private void doOwnerSearch(int ModelID, int Owner)
    {
        APP1DAL.TypedDs.dsDiagramPermissionAdminTableAdapters.DiagramPermissionAdminTableAdapter ds = new APP1DAL.TypedDs.dsDiagramPermissionAdminTableAdapters.DiagramPermissionAdminTableAdapter();
        dtDiagrams = ds.GetDiagramPermission(ModelID, Owner);
        this.GridViewOwners.DataSource = dtDiagrams.DefaultView;
        this.GridViewOwners.DataBind();
        Session["BindView"] = dtDiagrams;
        int intStartRecord = (GridViewOwners.PageIndex * GridViewOwners.PageSize) + 1;
        int intEndRecord = (GridViewOwners.PageIndex * GridViewOwners.PageSize) + GridViewOwners.Rows.Count;
        int intCurrentPage = GridViewOwners.PageIndex + 1;
        int intTotalRecords = dtDiagrams.Rows.Count;
        if (intTotalRecords > 0)
 
        {
            this.lblTotalCountText.Visible = true;
            lblTotalCountText.Text = "Displaying records " + intStartRecord.ToString() +
                " through " + intEndRecord.ToString() + " of " + intTotalRecords.ToString()
                + " items found (page " + intCurrentPage.ToString() +
                " of " + GridViewOwners.PageCount.ToString() + ")!"; 
        }
        else
        {
            this.lblTotalCountText.Visible = true;
            this.lblTotalCountText.Text = "No Diagrams Found";
        }
        
    }
 
    public void bindDropOwners(object sender, GridViewRowEventArgs e)
    {
 
        APP1BLL.UserSecurity.UserSecurity uSec = new APP1BLL.UserSecurity.UserSecurity();
        APP1DAL.TypedDs.dsUserTable.UserTableDataTable dtUser =
            new APP1DAL.TypedDs.dsUserTable.UserTableDataTable();
        try
        {
            dtUser = uSec.GetAllActiveUsers();
            DropDownList drpDiagramOwner = (DropDownList)e.Row.FindControl("drpDiagramOwner");
            drpDiagramOwner.DataSource = dtUser;
            drpDiagramOwner.DataTextField = dtUser.UsernameColumn.ColumnName;
            drpDiagramOwner.DataValueField = dtUser.UserIDColumn.ColumnName;
            drpDiagramOwner.DataBind();
 
 
        }
        catch (Exception ex)
        {
            lblError.Text = ex.Message;
        }
 
    }
           
         

	Title
1	IDs and Databinding. Desperate for H…
2	How to connect DropDown Lists in Edit…

DropDownList Databinding Problem

Asked by mcourt in Programming for ASP.NET, Visual Studio

Tags: ASP.NET, Visual Studio

About this solution