Connecting XPO to a Database Server (ASP.NET)
- 2 minutes to read
To access a database server using XPO, a data access layer needs to be created and provided with connection settings. To accomplish this in an ASP.NET application, place the construction code into the Application_Start event handler in the Global.asax module of your Web Site. For information on how to add the Global.asax module to the Web Site, see Tutorial 6 - A Simple Guestbook (ASP.NET).
void Application_Start(object sender, EventArgs e) {
// Code that runs on the application startup
// Specify the connection string, which is used to open a database.
// It's supposed that you've already created the Comments database
// within the App_Data folder.
string conn = DevExpress.Xpo.DB.AccessConnectionProvider.GetConnectionString(
Server.MapPath("~\\App_Data\\Comments.mdb"));
DevExpress.Xpo.Metadata.XPDictionary dict =
new DevExpress.Xpo.Metadata.ReflectionDictionary();
// Initialize the XPO dictionary.
dict.GetDataStoreSchema(typeof(Comment).Assembly);
DevExpress.Xpo.DB.IDataStore store = DevExpress.Xpo.XpoDefault.GetConnectionProvider(conn,
DevExpress.Xpo.DB.AutoCreateOption.SchemaAlreadyExists);
DevExpress.Xpo.XpoDefault.DataLayer = new DevExpress.Xpo.ThreadSafeDataLayer(dict, store);
DevExpress.Xpo.XpoDefault.Session = null;
}
Note
When designing ASP.NET applications, using the ThreadSafeDataLayer object is recommended.
Handle the Web form’s Page_Init event to create a session for the XpoDataSource component. The session must be linked to the Data Layer:
using DevExpress.Xpo;
Session session1;
protected void Page_Init(object sender, EventArgs e) {
session1 = new Session();
XpoDataSource1.Session = session1;
}
When designing multi-user ASP.NET applications based on XPO, it’s recommended to create an XPO session for each request. Create a new session for each page, and dispose of it by overriding the Page.Render method.
protected override void Render(HtmlTextWriter writer) {
base.Render(writer);
session1.Dispose();
}