FileAttachmentAttribute Class

Applied to business classes that expose a property of the IFileData type. Activates Controllers that manage file attachments for the target business class. Specifies a property that stores a file attachment.

Namespace: DevExpress.Persistent.Base

Assembly: DevExpress.Persistent.Base.v24.2.dll

NuGet Package: DevExpress.Persistent.Base

Declaration

C#

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Interface, Inherited = true)]
public class FileAttachmentAttribute :
    Attribute

VB.NET

<AttributeUsage(AttributeTargets.Class Or AttributeTargets.Interface, Inherited:=True)>
Public Class FileAttachmentAttribute
    Inherits Attribute

Remarks

Use this attribute to activate the following Controllers that provide Actions to manage file attachments:

• FileAttachmentController (ASP.NET Web Forms)
• FileAttachmentController (Windows Forms)
• FileAttachmentListViewController (Windows Forms)

The FileAttachmentAttribute attribute takes a single parameter - the FileAttachmentAttribute.FileDataPropertyName. The parameter specifies the property of a IFileData type to be used by the Controllers listed above. The snippet below illustrate the FileAttachmentAttribute attribute usage.

C# (EF Core)

[FileAttachmentAttribute(nameof(File))]
public class MyFileAttachment : BaseObject {
    public virtual FileData File { get; set; }
}

public class FileData : BaseObject, IFileData {
    // ...
}

// Make sure that you use options.UseChangeTrackingProxies() in your DbContext settings.

C# (XPO)

[FileAttachmentAttribute(nameof(File))]
public class MyFileAttachment : BaseObject {
    // ...
    private FileData file;
    public FileData File {
        get { return file; }
        set { SetPropertyValue(nameof(File), ref file, value); }
    }
}
public class FileData : BaseObject, IFileData {
   // ...
}

VB.NET (XPO)

<FileAttachmentAttribute(NameOf(File))>
Public Class MyFileAttachment
    Inherits BaseObject
    ' ...
    Private _file As FileData
    Public Property File() As FileData
        Get
            Return _file
        End Get
        Set(ByVal value As FileData)
            SetPropertyValue(NameOf(File), _file, value)
        End Set
    End Property
End Class
Public Class FileData
    Implements IFileData
   ' ...
End Class

As an alternative to using the FileAttachmentAttribute, you can inherit from the FileAttachmentBase class. It has the FileAttachmentAttribute applied, and exposes the File property to store file attachments.

Note

It is not recommended to use the DataView mode with the FileAttachmentAttribute. In this mode, a separate request to database is made for each focused List View record.

Inheritance

Object

Attribute

FileAttachmentAttribute