IObjectSpace.GetObjects(Type, CriteriaOperator) Method

Returns an IList collection of objects of the specified type, retrieved to the current Object Space and filtered according to the specified criteria.

Namespace: DevExpress.ExpressApp

Assembly: DevExpress.ExpressApp.v24.2.dll

NuGet Package: DevExpress.ExpressApp

Declaration

C#

IList GetObjects(
    Type type,
    CriteriaOperator criteria
)

VB.NET

Function GetObjects(
    type As Type,
    criteria As CriteriaOperator
) As IList

Parameters

Name	Type	Description
type	Type	The type of objects that are retrieved.
criteria	CriteriaOperator	A CriteriaOperator which specifies the criteria for object selection.

Returns

Type	Description
IList	A IList collection that contains the persistent objects of the specified type. Only objects that satisfy the specified criteria will be retrieved to this collection.

Remarks

The following example uses a Parametrized Action to search for a Person by LastName, and then assigns all deferred tasks to that person.

C#

using System.Collections;
using DevExpress.Data.Filtering;
using DevExpress.ExpressApp;
using DevExpress.ExpressApp.Actions;
using DevExpress.Persistent.Base;
using DevExpress.Persistent.Base.General;
using DevExpress.Persistent.BaseImpl;
// ...
public class AssignTasksController : ObjectViewController<ListView, MainDemo.Module.BusinessObjects.DemoTask> {
    public AssignTasksController() {
        ParametrizedAction assignTasksAction = new ParametrizedAction(
            this, "AssignTasks", PredefinedCategory.Edit, typeof(string));
        assignTasksAction.Execute += AssignTasksAction_Execute;
    }
    private void AssignTasksAction_Execute(object sender, ParametrizedActionExecuteEventArgs e) {
        IObjectSpace objectSpace = View.ObjectSpace;
        string personParamValue = e.ParameterCurrentValue as string;
        Person person = objectSpace.FirstOrDefault<Person>(p => p.LastName.Contains(personParamValue));
        if(person != null) {
            CriteriaOperator taskCriteria = CriteriaOperator.Parse("[Status] = ?", TaskStatus.Deferred);
            IList tasks = objectSpace.GetObjects(
                typeof(MainDemo.Module.BusinessObjects.DemoTask), taskCriteria);
            foreach(MainDemo.Module.BusinessObjects.DemoTask task in tasks) {
                task.AssignedTo = person;
            }
        }
    }
}

VB.NET

Imports System.Collections
Imports DevExpress.Data.Filtering
Imports DevExpress.ExpressApp
Imports DevExpress.ExpressApp.Actions
Imports DevExpress.Persistent.Base
Imports DevExpress.Persistent.Base.General
Imports DevExpress.Persistent.BaseImpl

Public Class AssignTasksController
    Inherits ObjectViewController(Of ListView, MainDemo.Module.BusinessObjects.DemoTask)
    Public Sub New()
        Dim assignTasksAction As New ParametrizedAction(Me, "AssignTasks", PredefinedCategory.Edit, GetType(String))
        AddHandler assignTasksAction.Execute, AddressOf AssignTasksAction_Execute
    End Sub
    Private Sub AssignTasksAction_Execute(ByVal sender As Object, ByVal e As ParametrizedActionExecuteEventArgs)
        Dim objectSpace As IObjectSpace = View.ObjectSpace
        Dim personParamValue As String = TryCast(e.ParameterCurrentValue, String)
        Dim person As Person = objectSpace.FirstOrDefault(Function (p as Person) p.LastName.Contains(personParamValue))
        If person IsNot Nothing Then
            Dim taskCriteria As CriteriaOperator = CriteriaOperator.Parse("[Status] = ?", TaskStatus.Deferred)
            Dim tasks As IList = objectSpace.GetObjects( _
                GetType(MainDemo.Module.BusinessObjects.DemoTask), taskCriteria)
            For Each task As MainDemo.Module.BusinessObjects.DemoTask In tasks
                task.AssignedTo = person
            Next task
        End If
    End Sub
End Class

When implementing the IObjectSpace interface in the BaseObjectSpace class’s descendant, don’t implement the GetObjects method. It’s implemented in the BaseObjectSpace class. To get the specified objects, the BaseObjectSpace.GetObjects(Type type, CriteriaOperator criteria) method invokes a protected virtual CreateCollection method that does nothing and returns null. So, you should override the CreateCollection method in your descendant.