aspnet-5334-components-grid-view-examples-how-to-hide-expand-buttons-for-master-rows-that-have-empty-details.md
This example uses the server-side DetailRowGetButtonVisibility event to hide the detail button for "empty" detail rows.
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<%@ Register Assembly="DevExpress.Web.v13.2, Version=13.2.13.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a"
Namespace="DevExpress.Web.ASPxGridView" TagPrefix="dx" %>
<%@ Register Assembly="DevExpress.Web.v13.2, Version=13.2.13.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a"
Namespace="DevExpress.Web.ASPxEditors" TagPrefix="dx" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>How to hide the detail button if the detail grid is empty</title>
</head>
<body>
<form id="form1" runat="server">
<div>
</div>
<dx:ASPxGridView ID="mainGrid" runat="server" AutoGenerateColumns="False" DataSourceID="masterDataSource"
KeyFieldName="CategoryID" OnDataBinding="masterGrid_DataBinding" OnDetailRowGetButtonVisibility="masterGrid_DetailRowGetButtonVisibility">
<Templates>
<DetailRow>
<dx:ASPxGridView ID="detailGrid" runat="server" AutoGenerateColumns="False" DataSourceID="dsDetail"
KeyFieldName="ProductID" OnBeforePerformDataSelect="detailGrid_BeforePerformDataSelect"
Width="100%">
<Styles>
<DetailRow HorizontalAlign="Justify">
</DetailRow>
</Styles>
<Columns>
<dx:GridViewDataTextColumn FieldName="ProductID" ReadOnly="True" VisibleIndex="0">
<EditFormSettings Visible="False" />
</dx:GridViewDataTextColumn>
<dx:GridViewDataTextColumn FieldName="ProductName" VisibleIndex="1">
</dx:GridViewDataTextColumn>
<dx:GridViewDataTextColumn FieldName="UnitPrice" VisibleIndex="2">
</dx:GridViewDataTextColumn>
</Columns>
</dx:ASPxGridView>
</DetailRow>
</Templates>
<Columns>
<dx:GridViewDataTextColumn FieldName="CategoryID" ReadOnly="True" VisibleIndex="0">
<EditFormSettings Visible="False" />
</dx:GridViewDataTextColumn>
<dx:GridViewDataTextColumn FieldName="CategoryName" VisibleIndex="1">
</dx:GridViewDataTextColumn>
<dx:GridViewDataTextColumn FieldName="Description" VisibleIndex="2">
</dx:GridViewDataTextColumn>
</Columns>
<SettingsDetail ShowDetailRow="True" />
</dx:ASPxGridView>
<asp:AccessDataSource ID="dsDetail" runat="server" DataFile="~/App_Data/nwind.mdb"
SelectCommand="SELECT [ProductID], [ProductName], [CategoryID], [UnitPrice] FROM [Products] WHERE ([CategoryID] = ?)">
<SelectParameters>
<asp:SessionParameter DefaultValue="CategoryID" Name="CategoryID" SessionField="CategoryID"
Type="Int32" />
</SelectParameters>
</asp:AccessDataSource>
<asp:AccessDataSource ID="masterDataSource" runat="server" DataFile="~/App_Data/nwind.mdb"
SelectCommand="SELECT * FROM [Categories]"></asp:AccessDataSource>
</form>
</body>
</html>
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using DevExpress.Web.ASPxGridView;
using DevExpress.Web.Data;
using System.Drawing;
using System.Collections;
using System.Data;
public partial class _Default : System.Web.UI.Page {
protected void masterGrid_DataBinding (object sender, EventArgs e) {
DoSelect(masterDataSource.DataFile);
}
private void DoSelect (string connectionString) {
DataView selectResult = new DataView();
string selectCommand = "select distinct [CategoryID] from [Products]";
using (AccessDataSource ds = new AccessDataSource(connectionString, selectCommand)) {
selectResult = (DataView)ds.Select(DataSourceSelectArguments.Empty);
}
ArrayList result = new ArrayList();
foreach (DataRow row in selectResult.Table.Rows)
result.Add(row["CategoryID"]);
Session["SelectResult"] = result;
}
protected void masterGrid_DetailRowGetButtonVisibility
(object sender, ASPxGridViewDetailRowButtonEventArgs e) {
if (!((ArrayList)Session["SelectResult"]).Contains(e.KeyValue))
e.ButtonState = GridViewDetailRowButtonState.Hidden;
}
protected void detailGrid_BeforePerformDataSelect (object sender, EventArgs e) {
Session["CategoryID"] = (sender as ASPxGridView).GetMasterRowKeyValue();
}
}
Imports Microsoft.VisualBasic
Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports DevExpress.Web.ASPxGridView
Imports DevExpress.Web.Data
Imports System.Drawing
Imports System.Collections
Imports System.Data
Partial Public Class _Default
Inherits System.Web.UI.Page
Protected Sub masterGrid_DataBinding(ByVal sender As Object, ByVal e As EventArgs)
DoSelect(masterDataSource.DataFile)
End Sub
Private Sub DoSelect(ByVal connectionString As String)
Dim selectResult As New DataView()
Dim selectCommand As String = "select distinct [CategoryID] from [Products]"
Using ds As New AccessDataSource(connectionString, selectCommand)
selectResult = CType(ds.Select(DataSourceSelectArguments.Empty), DataView)
End Using
Dim result As New ArrayList()
For Each row As DataRow In selectResult.Table.Rows
result.Add(row("CategoryID"))
Next row
Session("SelectResult") = result
End Sub
Protected Sub masterGrid_DetailRowGetButtonVisibility(ByVal sender As Object, ByVal e As ASPxGridViewDetailRowButtonEventArgs)
If Not(CType(Session("SelectResult"), ArrayList)).Contains(e.KeyValue) Then
e.ButtonState = GridViewDetailRowButtonState.Hidden
End If
End Sub
Protected Sub detailGrid_BeforePerformDataSelect(ByVal sender As Object, ByVal e As EventArgs)
Session("CategoryID") = (TryCast(sender, ASPxGridView)).GetMasterRowKeyValue()
End Sub
End Class
<%@ Page Language="vb" AutoEventWireup="true" CodeFile="Default.aspx.vb" Inherits="_Default" %>
<%@ Register Assembly="DevExpress.Web.ASPxGridView.v10.1, Version=10.1.12.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a"
Namespace="DevExpress.Web.ASPxGridView" TagPrefix="dx" %>
<%@ Register Assembly="DevExpress.Web.ASPxEditors.v10.1, Version=10.1.12.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a"
Namespace="DevExpress.Web.ASPxEditors" TagPrefix="dx" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>How to hide the detail button if the detail grid is empty</title>
</head>
<body>
<form id="form1" runat="server">
<div>
</div>
<dx:ASPxGridView ID="mainGrid" runat="server" AutoGenerateColumns="False" DataSourceID="masterDataSource"
KeyFieldName="CategoryID" OnDataBinding="masterGrid_DataBinding" OnDetailRowGetButtonVisibility="masterGrid_DetailRowGetButtonVisibility">
<Templates>
<DetailRow>
<dx:ASPxGridView ID="detailGrid" runat="server" AutoGenerateColumns="False" DataSourceID="dsDetail"
KeyFieldName="ProductID" OnBeforePerformDataSelect="detailGrid_BeforePerformDataSelect"
Width="100%">
<Styles>
<DetailRow HorizontalAlign="Justify">
</DetailRow>
</Styles>
<Columns>
<dx:GridViewDataTextColumn FieldName="ProductID" ReadOnly="True" VisibleIndex="0">
<EditFormSettings Visible="False" />
</dx:GridViewDataTextColumn>
<dx:GridViewDataTextColumn FieldName="ProductName" VisibleIndex="1">
</dx:GridViewDataTextColumn>
<dx:GridViewDataTextColumn FieldName="UnitPrice" VisibleIndex="2">
</dx:GridViewDataTextColumn>
</Columns>
</dx:ASPxGridView>
</DetailRow>
</Templates>
<Columns>
<dx:GridViewDataTextColumn FieldName="CategoryID" ReadOnly="True" VisibleIndex="0">
<EditFormSettings Visible="False" />
</dx:GridViewDataTextColumn>
<dx:GridViewDataTextColumn FieldName="CategoryName" VisibleIndex="1">
</dx:GridViewDataTextColumn>
<dx:GridViewDataTextColumn FieldName="Description" VisibleIndex="2">
</dx:GridViewDataTextColumn>
</Columns>
<SettingsDetail ShowDetailRow="True" />
</dx:ASPxGridView>
<asp:AccessDataSource ID="dsDetail" runat="server" DataFile="~/App_Data/nwind.mdb"
SelectCommand="SELECT [ProductID], [ProductName], [CategoryID], [UnitPrice] FROM [Products] WHERE ([CategoryID] = ?)">
<SelectParameters>
<asp:SessionParameter DefaultValue="CategoryID" Name="CategoryID" SessionField="CategoryID"
Type="Int32" />
</SelectParameters>
</asp:AccessDataSource>
<asp:AccessDataSource ID="masterDataSource" runat="server" DataFile="~/App_Data/nwind.mdb"
SelectCommand="SELECT * FROM [Categories]"></asp:AccessDataSource>
</form>
</body>
</html>