Mega Code Archive
Concurrency and the ObjectDataSource Control, ConflictDetection
<![CDATA[
<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<script runat="server">
protected void srcProducts_Updated(object sender, ObjectDataSourceStatusEventArgs e)
{
if (e.Exception != null)
{
e.ExceptionHandled = true;
lblError.Text = "Could not update record";
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>Show Conflict Detection</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Label
id="lblError"
EnableViewState="false"
CssClass="error"
Runat="server" />
<asp:GridView
id="grdProducts"
DataSourceID="srcProducts"
DataKeyNames="Id"
AutoGenerateEditButton="true"
Runat="server" />
<asp:ObjectDataSource
id="srcProducts"
ConflictDetection="CompareAllValues"
OldValuesParameterFormatString="original_{0}"
TypeName="ConflictedProducts"
SelectMethod="GetProducts"
UpdateMethod="UpdateProduct"
OnUpdated="srcProducts_Updated"
Runat="server" />
</div>
</form>
</body>
</html>
File: ConflictedProducts.cs
using System;
using System.Data;
using System.Data.SqlClient;
using System.Web.Configuration;
public class ConflictedProducts
{
private static readonly string _conString;
public static SqlDataReader GetProducts()
{
SqlConnection con = new SqlConnection(_conString);
SqlCommand cmd = new SqlCommand();
cmd.Connection = con;
cmd.CommandText = "SELECT Id,Title,Director FROM Products";
con.Open();
return cmd.ExecuteReader(CommandBehavior.CloseConnection);
}
public static void UpdateProduct(string title, string director, string original_title, string original_director, int original_id)
{
SqlConnection con = new SqlConnection(_conString);
SqlCommand cmd = new SqlCommand();
cmd.Connection = con;
cmd.CommandText = "UPDATE Products SET Title=@Title,Director=@Director"
+ " WHERE Id=@original_Id AND Title=@original_Title AND Director=@original_Director";
cmd.Parameters.AddWithValue("@Title", title);
cmd.Parameters.AddWithValue("@Director", director);
cmd.Parameters.AddWithValue("@original_Id", original_id);
cmd.Parameters.AddWithValue("@original_Title", original_title);
cmd.Parameters.AddWithValue("@original_Director", original_director);
using (con)
{
con.Open();
int rowsAffected = cmd.ExecuteNonQuery();
if (rowsAffected == 0)
throw new Exception("Could not update Product record");
}
}
static ConflictedProducts()
{
_conString = WebConfigurationManager.ConnectionStrings["Products"]. ConnectionString;
}
}
File: Web.config
<configuration>
<connectionStrings>
<add name="Products"
connectionString="Data Source=.\SQLEXPRESS;
AttachDbFilename=|DataDirectory|MyDatabase.mdf;Integrated Security=True;User Instance=True" />
</connectionStrings>
</configuration>
]]>