XafApplication.CreateCustomModelCacheManager Event

Occurs when the object used to manage saving and loading the Application Model cache is created.

Namespace: DevExpress.ExpressApp

Assembly: DevExpress.ExpressApp.v24.1.dll

NuGet Package: DevExpress.ExpressApp

Declaration

C#

public event EventHandler<CreateCustomModelCacheManagerEventArgs> CreateCustomModelCacheManager

VB.NET

Public Event CreateCustomModelCacheManager As EventHandler(Of CreateCustomModelCacheManagerEventArgs)

Event Data

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

Property	Description
ModelCacheManager	Specifies the object that manages the Application Model cache.

Remarks

By default, the Application Model content is cached to the Model.Cache.xafml file when the XafApplication.EnableModelCache property is set to true. To use a custom storage for the cache, handle the CreateCustomModelCacheManager event and pass a custom ModelCacheManager object to the CreateCustomModelCacheManagerEventArgs.ModelCacheManager parameter.

Tip

To change the cache file location, override the XafApplication.GetModelCacheFileLocationPath method instead of using this event.

The following example demonstrates the custom ModelCacheManager implementation.

C#

using System.Collections.Generic;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;
// ...
public class MyModelCacheManager : ModelCacheManager {
    string fileName = "MyCacheFile.bin";
    public MyModelCacheManager() : base(null, AppDomain.CurrentDomain.SetupInformation.ApplicationBase) { }
    public MyModelCacheManager(Stream stream, string modelCacheFileLocationPath)
        : base(stream, modelCacheFileLocationPath) {
    }
    protected override bool CanLoadModelCache() {
        return File.Exists(fileName);
    }
    protected override IDictionary<string, string> LoadCore() {
        Dictionary<string, string> serializedModel = null;
        using (FileStream loadStream = new FileStream(fileName, FileMode.Open, FileAccess.Read)) {
            BinaryFormatter bf = new BinaryFormatter();
            serializedModel = bf.Deserialize(loadStream) as Dictionary<string, string>;
        }
        return serializedModel;
    }
    protected override void SaveCore(Dictionary<string, string> serializedModel) {
        using (FileStream saveStream = new FileStream(fileName, FileMode.OpenOrCreate, FileAccess.ReadWrite)) {
            BinaryFormatter bf = new BinaryFormatter();
            bf.Serialize(saveStream, serializedModel);
        }
    }
}

VB.NET

Imports System.Collections.Generic
Imports System.IO
Imports System.Runtime.Serialization.Formatters.Binary
' ...
Public Class MyModelCacheManager
    Inherits ModelCacheManager
    Private fileName As String = "MyCacheFile.bin"
    Public Sub New()
        MyBase.New(Nothing, AppDomain.CurrentDomain.SetupInformation.ApplicationBase)
    End Sub
    Public Sub New(ByVal stream As Stream, ByVal modelCacheFileLocationPath As String)
        MyBase.New(stream, modelCacheFileLocationPath)
    End Sub
    Protected Overrides Function CanLoadModelCache() As Boolean
        Return File.Exists(fileName)
    End Function
    Protected Overrides Function LoadCore() As IDictionary(Of String, String)
        Dim serializedModel As Dictionary(Of String, String) = Nothing
        Using loadStream As New FileStream(fileName, FileMode.Open, FileAccess.Read)
            Dim bf As New BinaryFormatter()
            serializedModel = TryCast(bf.Deserialize(loadStream), Dictionary(Of String, String))
        End Using
        Return serializedModel
    End Function
    Protected Overrides Sub SaveCore(ByVal serializedModel As Dictionary(Of String, String))
        Using saveStream As New FileStream(fileName, FileMode.OpenOrCreate, FileAccess.ReadWrite)
            Dim bf As New BinaryFormatter()
            bf.Serialize(saveStream, serializedModel)
        End Using
    End Sub
End Class

To use this custom implementation, handle the CreateCustomModelCacheManager event in the Program.cs (Program.vb) file:

C#

winApplication.EnableModelCache = true;
winApplication.CreateCustomModelCacheManager += delegate(object sender, CreateCustomModelCacheManagerEventArgs e) {
    e.ModelCacheManager = new MyModelCacheManager();
};
winApplication.Setup();
winApplication.Start();

VB.NET

winApplication.EnableModelCache = True
AddHandler winApplication.CreateCustomModelCacheManager, Sub(sender As Object, e As CreateCustomModelCacheManagerEventArgs) e.ModelCacheManager = New MyModelCacheManager()
winApplication.Setup()
winApplication.Start()

The Application Model cache is not used when the debugger is attached (see Debugger.IsAttached). So, the CreateCustomModelCacheManager is not triggered when you debug your application in Visual Studio. If you need to temporarily enable caching to debug your custom code, set the ModelCacheManager.UseCacheWhenDebuggerIsAttached field to true in the WinApplication.cs (WinApplication.vb) file.

C#

ModelCacheManager.UseCacheWhenDebuggerIsAttached = true;

VB.NET

ModelCacheManager.UseCacheWhenDebuggerIsAttached = True

When you finished with debugging, remove this line. The model cache does not speed up your application startup in Visual Studio because the modules versions are constantly updated, and consequently, the cache is always recreated.