Object reference not set to an instance of an object.

Question

User-1473011517 posted

Help

=>

protected void btn1_Click(object sender, EventArgs e)
{
HLable.Text= (DetailsView1.FindControl("DateS1") as TextBox).Text;
}

=>

<asp:TemplateField HeaderText="Subject I">
<ItemTemplate>English (02)
<asp:TextBox ID="DateS1" runat="server" Text="02/09/2016" TextMode="SingleLine"></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>

Error

=>

Object reference not set to an instance of an object.

Answer 1

User283571144 posted

Hi vijaypwr61,

vijaypwr61

Object reference not set to an instance of an object.

This error is caused by FindControl method don't find the control.

As far as I know, if you want to find the textbox in DetailsView1, you need know its row index.

Then you could use findcontrol method find the textbox in  DetailsView's row.

More details, you could refer to follow codes:

Html:

 <div>
            <asp:DetailsView ID="DetailsView1" runat="server" Height="50px" Width="125px" AutoGenerateRows="False" DataKeyNames="Id" DataSourceID="SqlDataSource1">
                <Fields>
                    <asp:BoundField DataField="Id" HeaderText="Id" ReadOnly="True" SortExpression="Id" />
                    <asp:TemplateField HeaderText="City" SortExpression="City">
                        <EditItemTemplate>
                            <asp:TextBox ID="TextBox1" runat="server" Text='<%# Bind("City") %>'></asp:TextBox>
                        </EditItemTemplate>
                        <InsertItemTemplate>
                            <asp:TextBox ID="TextBox1" runat="server" Text='<%# Bind("City") %>'></asp:TextBox>
                        </InsertItemTemplate>
                        <ItemTemplate>
                            <asp:Label ID="Label1" runat="server" Text='<%# Bind("City") %>'></asp:Label>

                        </ItemTemplate>
                    </asp:TemplateField>
                    <asp:TemplateField HeaderText="Subject I">
                        <ItemTemplate>
                            English (02)
                            <asp:TextBox ID="DateS1" runat="server" Text="02/09/2016" TextMode="SingleLine"></asp:TextBox>
                        </ItemTemplate>
                    </asp:TemplateField>
                </Fields>
            </asp:DetailsView>
            <br />
            <asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_Click" />
            <asp:Label ID="Label2" runat="server" Text="Label"></asp:Label>
            <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:MysqlConnectionString %>" SelectCommand="SELECT * FROM [City]"></asp:SqlDataSource>
        </div>

Code-behind:

   protected void Button1_Click(object sender, EventArgs e)
        {
            TextBox tex =(TextBox)DetailsView1.Rows[0].FindControl("DateS1");
            Label2.Text = tex.Text;
        }

Best Regards,

Brando

Answer 2

User-1473011517 posted

Thank you.