How to Hide a Column (Gridview) But Still Access Its Value

How to hide a column (GridView) but still access its value?

If I am not mistaken, GridView does not hold the values of BoundColumns that have the attribute visible="false". Two things you may do here, one (as explained in the answer from V4Vendetta) to use Datakeys. Or you can change your BoundColumn to a TemplateField. And in the ItemTemplate, add a control like Label, make its visibility false and give your value to that Label.

GridView - Hide Column but Use Value

Here's a general overview of what you can do. It's not complicated. You databind as usual, but while doing that you find the index of the ID column. Then you use that index to hide the column on the RowCreated event. If you search for how to hide a column using auto-generated columns, you'll run into several answers following the method I'm using for hiding.

Private IDColumnIndex As Integer      //Class scope - we need to use it in multiple methods

Public Sub PageLoad() Handles Me.Load //or wherever your databind is happening
    Dim source As New DataTable()
    IDColumnIndex = source.Columns("id").Ordinal   //Gets column index of "ID" column

    view.DataSource = source
    view.DataBind()
End Sub

//Hide our "ID" auto-generated column.
Public Sub view_RowCreated(ByVal sender As Object, ByVal e As GridViewRowEventArgs) Handles view.RowCreated
    e.Row.Cells(IDColumnIndex).Visible = False
End Sub

How to hide a column but still access its value?

Set this code after you've binded the data. To get this functionality I do this:

MyGridView.Columns[0].visible = true;
MyGridView.DataBind();
MyGridView.Columns[0].visible = false;

With this the first column is hidden, but you should be able to acces it's value.

Getting cell value from hidden column

Instead of hiding that cell, use a TemplateField that contains an ASP.NET HiddenField control, like this:

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

Now in your code-behind, you can find the hidden field control, like this:

protected void hoursReportGridView_OnRowDataBound(Object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        HiddenField theHiddenField = e.Row.FindControl("HiddenFieldDifferentUsers") as HiddenField;

        // Check that we successfully found hidden field before using it
        if(theHiddenField != null)
        {
            // Do something with hidden field here if you need to
        }
    }
}

Hide BoundField's but still be able to get values with C#

Trevor is correct, you need to set your DataKeyNames like this in your DataGrid markup:

<asp:GridView ID="GridView1" runat="server" 
        DataKeyNames="PK_DailyTaskHours,PK_NonScrumStory"

Once you have done this you can get the values back as strings like this:

        protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
    {
        string dailyTaskHoursPK = GridView1.DataKeys[0].Values["PK_DailyTaskHours"].ToString();
        string nonScrumStoryPK = GridView1.DataKeys[0].Values["PK_NonScrumStory"].ToString();
    }

how to hide a column in gridview based on a condition?

You can hide columns in code behind.

if (User.IsInRole("Admin") == false)
{
    GridView1.Columns[0].Visible = false;
}

Or as one-liner.

GridView1.Columns[0].Visible = !User.IsInRole("Admin");

Get the value of hidden column in Gridview

One way I have gotten values from Invisible GridView Columns is using the DataKeyNames attribute.

<asp:GridView runat="server" ID="GridView" DataKeyNames="ColName1, ColName2">
</asp:GridView>

then to access the data

var data = GridView.DataKeys[RowIndex].Values[KeyIndex]

Make Gridview column invisible, but still access its data

Wherever you want to use the column value just use <%# Eval("ColumnName") %> inside the GridView.

All the datasource (dataset in your case) values are available in the DataBinder within the context of the GridView.

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