View.ObjectSpace Property

Provides access to the object space within which a View was created.

Namespace: DevExpress.ExpressApp

Assembly: DevExpress.ExpressApp.v23.2.dll

NuGet Package: DevExpress.ExpressApp

Declaration

C#

public virtual IObjectSpace ObjectSpace { get; }

VB.NET

Public Overridable ReadOnly Property ObjectSpace As IObjectSpace

Property Value

Type	Description
IObjectSpace	An IObjectSpace object representing the current View’s Object Space.

Remarks

An Object Space (see BaseObjectSpace) represents an instrument that allows managing a cache with persistent objects that are currently used in a View. Via an Object Space, a particular objects set is retrieved from the database to a data set. This allows making changes to objects within this data set, and canceling changes. This does not influence the general database. Use this property to access the current View’s Object Space.

Note

Do not use a root View’s Object Space for the creation of another root View in it. Instead, create a new Object Space via the XafApplication.CreateObjectSpace method for the new root View.

Note

The ObjectSpace property is not supposed to be used in scenarios where a large amount of data is processed, created or deleted. Instead, use an independent Object Space which is not used by a View. Such an Object Space can be instantiated via the XafApplication.CreateObjectSpace method.

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.Generic;
using DevExpress.Data.Filtering;
using DevExpress.ExpressApp;
using DevExpress.ExpressApp.Actions;
using DevExpress.Persistent.Base;
using DevExpress.Persistent.Base.General;
using DevExpress.Persistent.BaseImpl;
using MainDemo.Module.BusinessObjects;
// ...
public class AssignTasksController : ObjectViewController<ListView, 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<DemoTask> tasks = objectSpace.GetObjects<DemoTask>(taskCriteria);
            foreach(DemoTask task in tasks) {
                task.AssignedTo = person;
            }
        }
    }
}

VB.NET

Imports System.Collections.Generic
Imports DevExpress.Data.Filtering
Imports DevExpress.ExpressApp
Imports DevExpress.ExpressApp.Actions
Imports DevExpress.Persistent.Base
Imports DevExpress.Persistent.Base.General
Imports DevExpress.Persistent.BaseImpl
Imports MainDemo.Module.BusinessObjects

Public Class AssignTasksController
    Inherits ObjectViewController(Of ListView, 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(Of DemoTask) = objectSpace.GetObjects(Of DemoTask)(taskCriteria)
            For Each task As DemoTask In tasks
                task.AssignedTo = person
            Next task
        End If
    End Sub
End Class

Related GitHub Examples

The following code snippets (auto-collected from DevExpress Examples) contain references to the ObjectSpace property.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

C#

XAF_Non-Persistent-Objects-Nested-In-Persistent-Objects-Demo/CS/NonPersistentObjectsDemo.Win/WinApplication.cs#L71

    objectType == typeof(NonPersistentObjectsDemo.Module.BusinessObjects.Agent)) {
    return sourceFrame.View.ObjectSpace;
}

xaf-how-to-highlight-invalid-properties-when-a-view-is-activated/CS/DXSample.Module/ImmediateValidationController.cs#L48

    ImmediateValidationTargetObjectsSelector objectsSelector = new ImmediateValidationTargetObjectsSelector();
    ValidateObjects(objectsSelector.GetObjectsToValidate(View.ObjectSpace, View.CurrentObject));
}

VB.NET

XAF_Non-Persistent-Objects-Nested-In-Persistent-Objects-Demo/VB/NonPersistentObjectsDemo.Win/WinApplication.vb#L66

If TypeOf sourceFrame.View Is ListView AndAlso sourceFrame.View.ObjectTypeInfo.Type Is GetType(NonPersistentObjectsDemo.Module.BusinessObjects.Agent) AndAlso objectType Is GetType(NonPersistentObjectsDemo.Module.BusinessObjects.Agent) Then
    Return sourceFrame.View.ObjectSpace
End If

xaf-how-to-highlight-invalid-properties-when-a-view-is-activated/VB/DXSample.Module/ImmediateValidationController.vb#L53

    Dim objectsSelector As ImmediateValidationTargetObjectsSelector = New ImmediateValidationTargetObjectsSelector()
    ValidateObjects(objectsSelector.GetObjectsToValidate(View.ObjectSpace, View.CurrentObject))
End If