File Attachment Properties

• Aug 11, 2025
• 4 minutes to read

XAF can display the File Data or PDF Viewer property editor for properties that hold file data. These properties must use a type that implements the IFileData interface. For instance, XAF’s built-in FileData type.

File Data Property Editor (Blazor, WinForms, Web Forms)

Enable the File Attachments module to display objects that implement the IFileData interface in the File Data Property Editor. The following lessons contain a detailed explanation on how to use the File Attachments module: Attach files to objects.

PDF Viewer Property Editor (Blazor, WinForms)

Enable the Office Module and assign PdfViewerPropertyEditor to a file data property to display PDF files in the PDF Viewer. Refer to the following topic for additional details: Use PDF Documents in Business Objects (CTP).

EF Core

using DevExpress.ExpressApp.Editors;
using DevExpress.Persistent.Base;
using DevExpress.Persistent.BaseImpl.EF;

namespace MainDemo.Module.BusinessObjects;

[DefaultClassOptions]
public class Resume : BaseObject {
    // ... 
    [FileTypeFilter("pdf-only", "PDF file", "*.pdf")]
    public virtual FileData File { get; set; }
    [EditorAlias(EditorAliases.PdfViewerPropertyEditor)]
    public FileData ResumeView => File;
}

XPO

using DevExpress.ExpressApp.Editors;
using DevExpress.Persistent.Base;
using DevExpress.Persistent.BaseImpl;
using DevExpress.Xpo;

namespace MainDemo.Module.BusinessObjects;

[FileAttachment(nameof(File))]
[DefaultClassOptions]
public class Resume : BaseObject {
    // ...
    [Aggregated, ExpandObjectMembers(ExpandObjectMembers.Never)]
    [FileTypeFilter("pdf-only", "PDF file", "*.pdf")]
    public FileData File {
        get {
            return file;
        }
        set {
            SetPropertyValue(nameof(File), ref file, value);
        }
    }
    [EditorAlias(EditorAliases.PdfViewerPropertyEditor)]
    public FileData ResumeView => File;
}

Tip

Try out File Data editor and PDF Viewer in the MainDemo.NET.EFCore demo application installed as part of the XAF package (see Resume objects). The default application location is %PUBLIC%\Documents\DevExpress Demos 25.1\Components\XAF\MainDemo.NET.EFCore.

ASP.NET Core Blazor

DxFileDataPropertyEditor

DxFileDataPropertyEditor displays the property’s value as a hyperlinked file name. A user can click the link to download the file. The Detail View displays the Select File and Clear buttons. A user should save changes after a file upload to display a link instead of a plain text file name. The editor displays upload progress.

Customize Maximum File Size and Allowed File Types

The following code snippet changes the uploaded file’s maximum size and specifies the allowed file types.

File: MySolution.Blazor.Server\Controllers\CustomizeFileSizeController.cs

using DevExpress.ExpressApp.FileAttachments.Blazor.Editors;
using DevExpress.ExpressApp;
using MySolution.Module.BusinessObjects;

namespace MySolution.Blazor.Server.Controllers;
public class CustomizeFileSizeController : ObjectViewController<DetailView, Resume> {
    protected override void OnActivated() {
        View.CustomizeViewItemControl<DxFileDataPropertyEditor>(this, editor => {
            editor.ComponentModel.AcceptedFileTypes = [".jpg", ".gif"];
            editor.ComponentModel.MaxFileSize = 1024 * 512;
        });
    }
}

PdfViewerPropertyEditor

DevExpress.ExpressApp.Office.Blazor.Editors.PdfViewerPropertyEditor displays PDF documents in a PDF Viewer property editor.

WinForms

Each WinForms Property Editor has a control that displays the corresponding property in a Detail View, and a repository item that displays the property in a List Editor that supports in-place editing.

FileDataPropertyEditor

The editor allows a user to perform the Open, SaveTo, and ClearContent Actions that FileAttachmentController contains. Use the editor’s context menu to execute these Actions. You can also click the editor’s ellipsis button or press Enter to execute the Open Action.

Control

FileDataEdit - a ButtonEdit descendant. The editor uses OpenFileDialog to attach a file.

Repository Item

RepositoryItemFileDataEdit - a RepositoryItemButtonEdit descendant.

PdfViewerPropertyEditor

DevExpress.ExpressApp.Office.Win.PdfViewerPropertyEditor displays PDF documents in a PDF Viewer property editor.

ASP.NET Web Forms

Each ASP.NET Web Forms Property Editor has two different controls that display a property in a Detail View and in Edit mode. These controls are listed below.

FileDataPropertyEditor

View Mode Control

A FileDataEdit control that uses the HtmlAnchor control to download a file.

Edit Mode Control

A FileDataEdit control that uses ASPxUploadControl to upload a new file and the HtmlAnchor control to download a file. In edit mode, FileDataEdit also contains the Change File and Clear buttons of the ASPxButton type.

Description

FileDataPropertyEditor displays the property’s value as a link with the file name. A user can click the link to download the file. In edit mode, the Change File and Clear buttons are shown. FileAttachmentController contains corresponding Actions.

FileDataPropertyEditor does not show the upload progress if the ImmediatePostDataAttribute is applied to the related FileData property or the IModelCommonMemberViewItem.ImmediatePostData option is enabled for the current View Item in Model Editor.