.NET Framework 4.5.2+
.NET Framework 4.5.2+
.NET Standard 2.0+

XPInstantFeedbackSource.ResolveSession Event

Occurs when the XPInstantFeedbackSource needs a Session, to retrieve objects from the data store.

Namespace: DevExpress.Xpo

Assembly: DevExpress.Xpo.v21.1.dll

Declaration

public event EventHandler<ResolveSessionEventArgs> ResolveSession

Event Data

The ResolveSession event's data class is ResolveSessionEventArgs. The following properties provide information specific to this event:

Property Description
Session Specifies the session to be used to load and save persistent objects.

Remarks

Handle this event, to supply a Session connected to the required data store to the XPInstantFeedbackSource. You should also handle the XPInstantFeedbackSource.DismissSession event, to dispose of the created session, if required. If the ResolveSession event is not handled, the XPInstantFeedbackSource instantiates a Session using the parameterless constructor (see Session.DefaultSession).

The ResolveSessionEventArgs class exposes the ResolveSessionEventArgs.Tag field which you can use to specify an arbitrary object. This object will be passed along with the Session property to the DismissSession event handler.

Example

This example demonstrates how to initialize a XPInstantFeedbackSource, to retrieve data from a “Person.Contact” data table (included in the AdventureWorks database shipped with MS SQL Server). The Person_Contact persistent class is declared, and mapped to the “Person.Contact” data table, using the PersistentAttribute attribute. Then, this class is used as a parameter in the XPInstantFeedbackSource constructor.

using DevExpress.Xpo;
using DevExpress.Xpo.DB;
using DevExpress.Data.Filtering;

// The persistent class describing the "Person.Contact" table 
// from the AdventureWorks SQL database
[Persistent("Person.Contact")]
public class Person_Contact : XPLiteObject {        
    [Key]
    public System.Int32 ContactID {
        get { return fContactID; }
        set { SetPropertyValue(nameof(ContactID), ref fContactID, value); }
    }
    System.Int32 fContactID;

    public string FirstName {
        get { return fFirstName; }
        set { SetPropertyValue(nameof(FirstName), ref fFirstName, value); }
    }
    string fFirstName;

    public string LastName {
        get { return fLastName; }
        set { SetPropertyValue(nameof(LastName), ref fLastName, value); }
    }
    string fLastName;

    //...
}
public partial class Form1 : Form {
    //...
    public Form1() {
        // ...
        // Create a filter that selects records where last names start with 'A'     
        CriteriaOperator criteria = CriteriaOperator.Parse("[LastName] LIKE ?", "A%");
        // Specify the properties that will be available for binding
        string displayableProperties = "FirstName;LastName";    
        // Initialize an XPInstantFeedbackSource data source 
        // supplying data from the Person.Contact data table     
        XPInstantFeedbackSource instantDS = new XPInstantFeedbackSource(
            typeof(Person_Contact), displayableProperties, criteria);
        // Handle the ResolveSession event, 
        // to provide a Session to the XPInstantFeedbackSource
        instantDS.ResolveSession += instantDS_ResolveSession;
        // Handle the DismissSession event, to dispose of the Session
        instantDS.DismissSession += instantDS_DismissSession;
        //...
    }
    void instantDS_ResolveSession(object sender, ResolveSessionEventArgs e) {
        Session session = new Session();
        session.ConnectionString = @"Integrated Security=SSPI;Pooling=false;
            Data Source=.\SQLEXPRESS;Initial Catalog=MyDatabase";
        session.Connect();
        e.Session = session;
    }
    void instantDS_DismissSession(object sender, ResolveSessionEventArgs e) {
        IDisposable session = e.Session as IDisposable;
        if(session != null) {
            session.Dispose();
        }
    }
}
See Also