Get Hidden Field Value

Question

I have a GridView defined as follows:

<asp:GridView ID="myGridView" AutoGenerateColumns="false" runat="server"
OnLoad="myGridView_Load" OnRowCommand="myGridView_Command" OnRowEditing="myGridView_RowEditing" OnRowDeleting="myGridView_RowDeleting" DataKeyNames="ID" > 
  <Columns>
    <asp:BoundField DataField="ID" Visible="false" />
    <asp:BoundField DataField="BirthDate" Visible="false" />
    <asp:BoundField DataField="FirstName" HeaderText="First Name" />
    <asp:BoundField DataField="LastName" HeaderText="Last Name" />
    <asp:TemplateField HeaderText="Other">
      <ItemTemplate>
        <asp:LinkButton ID="editLB" runat="server" Text="edit" CommandName="Edit" />
        <asp:LinkButton ID="deleteLB" runat="server" Text="delete" CommandName="Delete" />
      </ItemTemplate>
    </asp:TemplateField>
  </Columns>   
</asp:GridView>

When a user clicks the edit button, I need to get the value of the BirthDate column. To attempt this, I have tried the following:

protected void myGridView_RowEditing(object sender, GridViewEditEventArgs e)
{
  GridViewRow row = gvUsers.Rows[e.NewEditIndex];
  DateTime birthDate = (DateTime)(row.Cells[1].Text);

  // Does not work
}

I know it has something to do with the fact that the column is not visible. The column must be hidden. But I need to get that value— how can I do this?

Answer 1

The problem is that when the Visibility property of the BoundField is set to false the column isn't rendered to the client. A work around would be to use a HiddenField within a TemplateField instead.

<asp:TemplateField>
    <ItemTemplate>
        <asp:HiddenField ID="HiddenField1" runat="server" 
                         Value='<%# Eval("BirthDate") %>' />
    </ItemTemplate>
    <EditItemTemplate>
        <asp:HiddenField ID="HiddenField1" runat="server" 
                         Value='<%# Eval("BirthDate") %>' />
    </EditItemTemplate>
</asp:TemplateField>

protected void GridView_RowEditing(object sender, GridViewEditEventArgs e)
{
    GridViewRow row = GridView.Rows[e.NewEditIndex];     
    HiddenField  hidden = (HiddenField)row.Cells[0].FindControl("HiddenField1");
    DateTime birthDate = Convert.ToDateTime(hidden.Value);
}

EDIT

The above method still renders the column in the table, so you end up with an empty column. It works but not the best solution, here's a way the hide the BirthDate field but still get its value in the RowEditing event handler. Just keep in mind that the BirthDate is still rendered to the client, just not displayed.

<style type="text/css">
    .hide
    {
        display:none;
    }
</style>

<asp:BoundField DataField="BirthDate">
    <ItemStyle CssClass="hide"/>
</asp:BoundField>

protected void GridView_RowEditing(object sender, GridViewEditEventArgs e)
{
    GridViewRow row = GridView1.Rows[e.NewEditIndex];
    DateTime birthDate = Convert.ToDateTime(row.Cells[1].Text);
}

Answer 2

To hide the content as well as the Header in the Grid use the below code: and access the column as usual. GridView.SelectedRow.Cells[index].Text;

<style type="text/css">
.hide
{
    display:none;
}

<asp:BoundField DataField="MailRoomID" HeaderText="Mailroom ID" ItemStyle-HorizontalAlign="Center" ShowHeader="false" ><ItemStyle CssClass="hide" /><HeaderStyle CssClass="hide"/></asp:BoundField>

Answer 3

I have done something like this (adapting to your example):

string[] keyList = new string[1];   
keyList[0] = "BirthDate";  
myGridView.DataKeyNames = keyList;

I then bound the GridView with a DataTable that has a column named "BirthDate". The data under this column would be stored under the DataKeyName specified above.

To get the desired value, I would do something like this:

protected void myGridView_RowEditing(object sender, GridViewEditEventArgs e)  
{   
  DataKeyArray keyList = myGridView.DataKeys as DataKeyArray;
  if (keyList != null)       
    DateTime birthDate = keyList[e.NewEditIndex];    
}

I realize that this doesn't involve hidden fields, however.

Answer 4

Check out the following article that shows how to access GridView invisible columns:

http://www.highoncoding.com/Articles/178_Access_GridView_Invisible_Columns.aspx

The idea is to basically use a TemplateField column instead of a BoundColumn.