Most ASP.NET GridView control examples demonstrate using the GridView with a SQLDataSource. But in some cases, you may want to use your own business objects instead.
One way to achieve this goal is to use the ObjectDataSource as shown in MSDN here.
Another option is to simply bind the GridView directly to your business objects without using a DataSource control.
The example presented in this post uses business objects you build yourself. These "home made" business objects are often referred to as POCO, or "plain old CLR objects". Use the techniques presented in this post any time you want to use your business objects in a GridView without using a DataSource control.
Prerequisites
First, we need some business objects. This example uses a Customer class that defines a single customer, and a Customers (plural) class that returns a generic list of customers.
In C#:
public class Customer
{
public int CustomerId { get; set; }
public string LastName { get; set; }
public string FirstName { get; set; }
public string EmailAddress { get; set; }
}
public class Customers
{
public static List<Customer> Retrieve()
{
List<Customer> custList = new List<Customer>
{new Customer()
{ CustomerId = 1,
FirstName="Bilbo",
LastName = "Baggins",
EmailAddress = "bb@hob.me"},
new Customer()
{ CustomerId = 2,
FirstName="Frodo",
LastName = "Baggins",
EmailAddress = "fb@hob.me"},
new Customer()
{ CustomerId = 3,
FirstName="Samwise",
LastName = "Gamgee",
EmailAddress = "sg@hob.me"},
new Customer()
{ CustomerId = 4,
FirstName="Rosie",
LastName = "Cotton",
EmailAddress = "rc@hob.me"}};
return custList;
}
}
In VB:
Public Class Customer
Private _CustomerId As Integer
Public Property CustomerId() As Integer
Get
Return _CustomerId
End Get
Set(ByVal value As Integer)
_CustomerId = value
End Set
End Property
Private _FirstName As String
Public Property FirstName() As String
Get
Return _FirstName
End Get
Set(ByVal value As String)
_FirstName = value
End Set
End Property
Private _LastName As String
Public Property LastName() As String
Get
Return _LastName
End Get
Set(ByVal value As String)
_LastName = value
End Set
End Property
Private _EmailAddress As String
Public Property EmailAddress () As String
Get
Return _EmailAddress
End Get
Set(ByVal value As String)
_EmailAddress = value
End Set
End Property
End Class
Public Class Customers
Public Shared Function Retrieve() As List(Of Customer)
Dim custList As New List(Of Customer)
custList.Add(New Customer With {.CustomerId = 1, _
.LastName = "Baggins", _
.FirstName = "Bilbo", _
.EmailAddress = "bb@hob.me"})
custList.Add(New Customer With {.CustomerId = 2, _
.LastName = "Baggins", _
.FirstName = "Frodo", _
.EmailAddress = "fb@hob.me"})
custList.Add(New Customer With {.CustomerId = 3, _
.LastName = "Gamgee", _
.FirstName = "Samwise", _
.EmailAddress = "sg@hob.me"})
custList.Add(New Customer With {.CustomerId = 4, _
.LastName = "Cotton", _
.FirstName = "Rosie", _
.EmailAddress = "rc@hob.me"})
Return custList
End Function
End Class
The C# code here uses auto-implemented properties to shorten the property syntax. The VB code uses the full property syntax.
In a real application, the Retrieve method would collect the data from the database. This example uses hard-coded values to make it easier for you to try this code without having to set up data access.
NOTE: Since this example includes sorting and paging, you may want to add more test data to the lists to better see the sorting and paging in operation.
Define the GridView
The next step is to define the ASP.NET GridView control. This example creates the control using HTML, but you could create the control using code if desired.
In HTML:
<asp:GridView ID="CustomerGridView" runat="server"
AllowPaging="true" PageSize="3"
AllowSorting="true"
AutoGenerateColumns="false">
<Columns>
<asp:BoundField HeaderText="Last Name"
DataField="LastName" SortExpression="LastName" />
<asp:BoundField HeaderText="First Name"
DataField="FirstName" SortExpression="FirstName" />
<asp:BoundField HeaderText="Email"
DataField="EmailAddress" SortExpression="EmailAddress" />
</Columns>
</asp:GridView>
AllowPaging is set to true to demonstrate the paging feature. The PageSize is only set to 3 since this example includes such a small set of data. You can increase this number based on your user interface design.
AllowSorting is set to true to demonstrate the grid sorting feature. In addition, SortExpression was set for each BoundField.
AutoGenerateColumns is off so that the code can manually define the desired columns in the desired order.
Write the Code
Since there is no DataSource control in this example, you need to write code to perform the binding, sorting, and paging.
In this example, the Page_Load event calls the business object to obtain the data and performs the binding to that data.
ASP.NET generates the PageIndexChanging event when the grid is paging. So the code to handle the paging is in this event.
The Sorting event contains the code to handle the sorting. By default, the Sorting event will always request an ascending sort, so if you want your grid to sort both ascending and descending, you will need to handle that in the code. You can write the code so that when the user clicks on a column, the sort is ascending. If the user clicks on the same column again, the sort is descending. If the user clicks on a different column, the new column is sorted in ascending order.
In C#:
using System.Collections.Generic;
using System.Linq;
using System.Web.UI.WebControls;
using SampleBoCSharp;
namespace SampleWebCSharp
{
public partial class _Default : System.Web.UI.Page
{
public string LastSortKey
{
get { return ViewState["LastSortKey"].ToString(); }
set { ViewState["LastSortKey"] = value; }
}
public string LastSortDirection
{
get { return ViewState["LastSortDirection"].ToString(); }
set { ViewState["LastSortDirection"] = value; }
}
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
// Get the list of customers
List<Customer> customerList = Customers.Retrieve();
// Do the binding
CustomerGridView.DataSource = customerList;
CustomerGridView.DataBind();
// Store in a session variable
Session.Add("Customers", customerList);
// Set the sort info
LastSortDirection = string.Empty;
LastSortKey = string.Empty;
}
// Set up the events
CustomerGridView.PageIndexChanging +=
CustomerGridView_PageIndexChanging;
CustomerGridView.Sorting += CustomerGridView_Sorting;
}
private void CustomerGridView_PageIndexChanging(object sender,
GridViewPageEventArgs e)
{
// Get the list of customers from the session
List<Customer> customerList = default(List<Customer>);
customerList = Session["Customers"] as List<Customer>;
// Set the index
CustomerGridView.PageIndex = e.NewPageIndex;
// Rebind
CustomerGridView.DataSource = customerList;
CustomerGridView.DataBind();
}
private void CustomerGridView_Sorting(object sender,
GridViewSortEventArgs e)
{
// Get the list of customers from the session
List<Customer> customerList = default(List<Customer>);
customerList = Session["Customers"] as List<Customer>;
// Sort key is different, clear the last sort direction
if (LastSortKey != e.SortExpression) {
LastSortDirection = string.Empty;
}
// Perform the sort using Linq
switch (e.SortExpression) {
case "LastName":
customerList = Sort(customerList,
cust=> cust.LastName);
break;
case "FirstName":
customerList = Sort(customerList,
cust=> cust.FirstName);
break;
case "EmailAddress":
customerList = Sort(customerList,
cust => cust.EmailAddress);
break;
}
LastSortKey = e.SortExpression;
// Rebind
CustomerGridView.DataSource = customerList;
CustomerGridView.DataBind();
// Store in a session variable
Session.Add("Customers", customerList);
}
private List<Customer> Sort(List<Customer> list,
Func<Customer, string> sortKey)
{
if (LastSortDirection == "ASC") {
list = list.OrderByDescending(sortKey).ToList();
LastSortDirection = "DESC";
}
else {
list = list.OrderBy(sortKey).ToList();
LastSortDirection = "ASC";
}
return list;
}
}
}
In VB:
Partial Public Class _Default
Inherits System.Web.UI.Page
Public Property LastSortKey() As String
Get
Return ViewState("LastSortKey").ToString
End Get
Set(ByVal value As String)
ViewState("LastSortKey") = value
End Set
End Property
Public Property LastSortDirection() As String
Get
Return ViewState("LastSortDirection").ToString
End Get
Set(ByVal value As String)
ViewState("LastSortDirection") = value
End Set
End Property
Protected Sub Page_Load(ByVal sender As Object, _
ByVal e As System.EventArgs) Handles Me.Load
If Not IsPostBack Then
‘ Get the list of customers
Dim customerList As List(Of Customer)
customerList = Customers.Retrieve()
‘ Do the binding
CustomerGridView.DataSource = customerList
CustomerGridView.DataBind()
‘ Store in a session variable
Session.Add("Customers", customerList)
‘ Set the sort info
LastSortDirection = String.Empty
LastSortKey = String.Empty
End If
End Sub
Private Sub CustomerGridView_PageIndexChanging(ByVal sender As Object, ByVal e As GridViewPageEventArgs) Handles CustomerGridView.PageIndexChanging
‘ Get the list of customers from the session
Dim customerList As List(Of Customer)
customerList = TryCast(Session("Customers"),
List(Of Customer))
‘ Set the index
CustomerGridView.PageIndex = e.NewPageIndex
‘ Rebind
CustomerGridView.DataSource = customerList
CustomerGridView.DataBind()
End Sub
Private Sub CustomerGridView_Sorting(ByVal sender As Object,
ByVal e As GridViewSortEventArgs)
Handles CustomerGridView.Sorting
‘ Get the list of customers from the session
Dim customerList As List(Of Customer)
customerList = TryCast(Session("Customers"),
List(Of Customer))
‘ If the sort key is different, clear the last sort direction
If LastSortKey <> e.SortExpression Then
LastSortDirection = String.Empty
End If
‘ Perform the sort using Linq
Select Case e.SortExpression
Case "LastName"
customerList = Sort(customerList,
Function(cust) cust.LastName)
Case "FirstName"
customerList = Sort(customerList,
Function(cust) cust.FirstName)
Case "EmailAddress"
customerList = Sort(customerList,
Function(cust) cust.EmailAddress)
End Select
LastSortKey = e.SortExpression
‘ Rebind
CustomerGridView.DataSource = customerList
CustomerGridView.DataBind()
‘ Store in a session variable
Session.Add("Customers", customerList)
End Sub
Private Function Sort(ByVal list As List(Of Customer), _
ByVal sortKey As Func(Of Customer, String)) As List(Of Customer)
If LastSortDirection = "ASC" Then
list = list.OrderByDescending(sortKey).ToList()
LastSortDirection = "DESC"
Else
list = list.OrderBy(sortKey).ToList()
LastSortDirection = "ASC"
End If
Return list
End Function
End Class
The LastSortKey and LastSortDirection properties retain the sort criteria so that you can sort ascending or descending. The values are stored in the ViewState so they can be retained with the other page data.
The Page_Load event calls the Retrieve method on the Customers object to retrieve the list of customers. It then sets the DataSource property of the GridView and binds it.
NOTE: For the paging to work correctly, the GridView must be bound to a List.
The code then stores the customer list in a session variable. This is not necessary if you want to ensure that the data is fresh each time that it is sorted or paged.
Finally, it sets a default value into the LastSortKey and LastSortDirection properties so they are not null.
The PageIndexChanged event retrieves the list of customers from the session variable, sets the GridView PageIndex, and rebinds to the list.
NOTE: If you re-retrieve the customer list instead of storing/retrieving it from the session, you will need to resort it before rebinding because it will have lost any sorting.
The Sorting event retrieves the list of customers from the session variable. It then checks the last sort key and clears the LastSortDirection if the user clicked on a different column. It then performs the sort using a lambda expression.
Finally, it rebinds the GridView to the list and stores the sorted list back to the session variable.
The Sort method defined in this example takes the list and a lambda expression in as parameters, performs the sort, and returns the sorted list.
The result looks like this:
You can then style the grid to match your user interface design. And adding an image to show whether the column was sorted ascending or descending would also be nice.
Enjoy!
