Get text box value from grid view Header

Question

I have grid with text box for filter data on header.I have button outside the grid.I am using this gridview for filtering the grid by some columns. When I click on button I want to get value from text box and dropdownlist on codebehind.cs, below is my webform.aspx code of gridview,

<asp:Button ID="btngetLocationDate" runat="server" Text="Get Filtered Data" OnClick="getTextBoxValue"></asp:Button>

<asp:GridView ID="TrackerGrid" runat="server" BackColor="#CCCCCC" AllowPaging="True" AutoGenerateColumns="false">
    <AlternatingRowStyle HorizontalAlign="Center" VerticalAlign="Middle" />

    <Columns>
        <asp:TemplateField HeaderText="User ID" SortExpression="User ID">
            <ItemTemplate>
                <asp:Label ID="lbluserid" runat="server" Text='<%# Eval("User ID") %>'></asp:Label>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Customer Name">
            <HeaderTemplate>
                Full Name:
               <asp:DropDownList ID="ddlfullName" runat="server" AutoPostBack="true" OnSelectedIndexChanged="onselectDropdown">
                   <asp:ListItem Text="ALL" Value="ALL" Selected="True"></asp:ListItem>
               </asp:DropDownList>
            </HeaderTemplate>

            <ItemTemplate>
                <asp:Label ID="lblname" runat="server" Text='<%# Eval("Full Name") %>'></asp:Label>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Mobile Number">
            <HeaderTemplate>
                Mobile Number:
               <asp:TextBox ID="txtMobilenumber" runat="server" AutoPostBack="true"></asp:TextBox>

            </HeaderTemplate>
            <ItemTemplate>
                <asp:Label ID="lblmobile" runat="server" Text='<%# Eval("Mobile Phone") %>'></asp:Label>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Email Address">
            <HeaderTemplate>
                Email Id:
                          <asp:TextBox ID="txtemail" runat="server" AutoPostBack="true"></asp:TextBox>
            </HeaderTemplate>
            <ItemTemplate>
                <asp:Label ID="lblemail" runat="server" Text='<%# Eval("Email ID") %>'></asp:Label>
            </ItemTemplate>
        </asp:TemplateField>

        <asp:TemplateField HeaderText="Longitude">
            <HeaderTemplate>
                <asp:Label ID="lbllng" runat="server" Text="Longitude"></asp:Label>

            </HeaderTemplate>
            <ItemTemplate>
                <asp:Label ID="lbllongi" runat="server" Text='<%# Eval("Longitude") %>' Width="70"></asp:Label>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Lattitude">
            <HeaderTemplate>
                <asp:Label ID="lbllat" runat="server" Text="Lattitude"></asp:Label>

            </HeaderTemplate>
            <ItemTemplate>
                <asp:Label ID="lbllatti" runat="server" Text='<%# Eval("Lattitude") %>' Width="70"></asp:Label>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Activated On">
            <HeaderTemplate>
                <asp:Label ID="lbldevices" runat="server" Text="Activated On"></asp:Label></br>

            </HeaderTemplate>
            <ItemTemplate>
                <asp:Label ID="lbldevice" runat="server" Text='<%# Eval("Activated On") %>'></asp:Label>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Location DateTime" SortExpression="Location DateTime">
            <HeaderTemplate>
                <asp:Label ID="Label1" runat="server" Text="Location DateTime"></asp:Label></br>
                   <asp:Label ID="lblStartDate" runat="server" AssociatedControlID="txtStartDate" Text="Start Date"></asp:Label>
                <asp:TextBox ID="txtStartDate" runat="server"></asp:TextBox>
                <cc1:calendarextender id="CalendarStartDate" runat="server" format="dd/MM/yyyy" targetcontrolid="txtStartDate" popupbuttonid="imgPopup1"></cc1:calendarextender>

                <asp:ImageButton ID="imgPopup1" runat="server" ImageUrl="https://cdn4.iconfinder.com/data/icons/small-n-flat/24/calendar-alt-512.png" Height="20px" Width="30px" />
                </br>
                <asp:Label ID="lblEndDate" runat="server" Text="End Date" AssociatedControlID="txtEndDate"></asp:Label>
                &nbsp;&nbsp;<asp:TextBox ID="txtEndDate" runat="server"></asp:TextBox>
                <cc1:calendarextender id="CalendarEndDate" runat="server" format="dd/MM/yyyy" targetcontrolid="txtEndDate" popupbuttonid="imgPopup2"></cc1:calendarextender>

                <asp:ImageButton ID="imgPopup2" runat="server" ImageUrl="https://cdn4.iconfinder.com/data/icons/small-n-flat/24/calendar-alt-512.png" Height="20px" Width="30px" />

            </HeaderTemplate>
            <ItemTemplate>
                <asp:Label ID="lblDatetime" runat="server" Text='<%# Eval("Location DateTime") %>'></asp:Label>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

and I am getting texbox value in codebehind code.

protected void getTextBoxValue(object sender, EventArgs e)
{
    DropDownList ddlfullname = (TrackerGrid.HeaderRow.FindControl("ddlfullName") as DropDownList);
    string selectedValue = ddlfullname.SelectedItem.Text;

    TextBox mobilenumber = (TrackerGrid.HeaderRow.FindControl("txtMobilenumber") as TextBox);
    string mobile = mobilenumber.Text;


    TextBox email = TrackerGrid.HeaderRow.FindControl("txtemail") as TextBox;
    string emailid = email.Text;


    TextBox staloc = TrackerGrid.HeaderRow.FindControl("txtStartDate") as TextBox;
    string startlocatdate = staloc.Text;
    TextBox endloc = TrackerGrid.HeaderRow.FindControl("txtEndDate") as TextBox;
    string endlocadate = endloc.Text;
}

I am getting empty value when I debugging this code.I think my code is correct but how i am not getting value of textboxes, i don't understand. Please help me for solving my issue.

Thanks in advance.

Answer 1

You probably did not wrap the DataBind() of the Gridview inside an IspostBack check. If you do not then the values will be rested by the DataBind instead of being saved with ViewState.

protected void Page_Load(object sender, EventArgs e)
{
    //not here
    TrackerGrid.DataSource = source;
    TrackerGrid.DataBind();

    if (IsPostBack == false)
    {
        //but inside an ispostback check
        TrackerGrid.DataSource = source;
        TrackerGrid.DataBind();
    }
}