EntityInstantFeedbackSource.GetQueryable Event

Occurs when the EntityInstantFeedbackSource needs a queryable source, to retrieve objects from the data store.

Namespace: DevExpress.Data.Linq

Assembly: DevExpress.Data.v20.2.dll

Declaration

public event EventHandler<GetQueryableEventArgs> GetQueryable
Public Event GetQueryable As EventHandler(Of GetQueryableEventArgs)

Event Data

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

Property Description
AreSourceRowsThreadSafe Specifies whether elements retrieved by the LinqInstantFeedbackSource's queryable source are thread-safe.
KeyExpression Gets or sets the name of the key property.
QueryableSource Gets or sets the queryable data source.
Tag Gets or sets an arbitrary object associated with a queryable source.

Remarks

Handle this event, to supply a queryable source connected to the required data service. The GetQueryableEventArgs class exposes the GetQueryableEventArgs.Tag property, which you can use to specify an arbitrary object. This object will be passed along with the GetQueryableEventArgs.QueryableSource property to the EntityInstantFeedbackSource.DismissQueryable event handler.

public partial class Form1 : Form {
    private void Form1_Load(object sender, EventArgs e) {
        efInstantFeedbackSource1.KeyExpression = "EmployeeID";
        efInstantFeedbackSource1.GetQueryable += efInstantFeedbackSource1_GetQueryable;
        efInstantFeedbackSource1.DismissQueryable += efInstantFeedbackSource1_DismissQueryable;
        gridControl1.DataSource = efInstantFeedbackSource1;
    }
    void efInstantFeedbackSource1_GetQueryable(object sender, GetQueryableEventArgs e) {
        NorthwindEntities objectContext = new NorthwindEntities();
        e.QueryableSource = objectContext.Employees;
        e.Tag = objectContext;            
    }
    void efInstantFeedbackSource1_DismissQueryable(object sender, GetQueryableEventArgs e) {
        ((NorthwindEntities)e.Tag).Dispose();         
    }
}
See Also