Building an ASP.NET Web Application with Open XML Functionality

Web developers sometimes want to integrate some Open XML functionality into their web application.  You may want to enable end-users to upload documents.  You may want to modify the uploaded documents, or generate new documents, and you may want to enable end-users to download documents.  In the screen-cast below, I present the smallest possible ASP.NET application that enables uploading an Open XML document, modifying the document using the Open XML SDK, and letting the user download a document.  In the screen-cast, I show how to build the application, and I walk through the code.

Following is the ASP.NET markup for the web page in the application:

<%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true"
    CodeBehind="Default.aspx.cs" Inherits="WebApplication1._Default" %>

<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
</asp:Content>
<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
    <h2>
        Welcome to an ASP.NET Open XML Application!
    </h2>
    <asp:FileUpload ID="FileUploadControl" runat="server" />
    <p style="line-height: .5em;"/>
    <asp:Label ID="lblMessage" runat="server" Text=""></asp:Label>    
    <p style="line-height: .5em;"/>
    <asp:Button ID="btnUpload" runat="server" 
            Text="Upload an Open XML Document into the Web Application" 
            onclick="btnUpload_Click" />   
    <p style="line-height: .5em;"/>
    <asp:Button ID="btnDownload" runat="server" 
            Text="Download the modified Open XML document" onclick="btnDownload_Click" />    
    </asp:Content>

Following is the C# code for that web page:

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Xml;
using System.Xml.Linq;
using DocumentFormat.OpenXml.Packaging;

namespace WebApplication1
{
    public partial class _Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void btnUpload_Click(object sender, EventArgs e)
        {
            if (FileUploadControl.HasFile)
                try
                {
                    string fileNameFromUser = FileUploadControl.FileName;
                    Session["FileNameFromUser"] = fileNameFromUser;

                    using (MemoryStream memoryStream = new MemoryStream())
                    {
                        memoryStream.Write(FileUploadControl.FileBytes, 0,
                            FileUploadControl.FileBytes.Length);
                        using (WordprocessingDocument wDoc =
                            WordprocessingDocument.Open(memoryStream, true))
                        {
                            XNamespace w =
                                "http://schemas.openxmlformats.org/wordprocessingml/2006/main";

                            XElement body = wDoc.MainDocumentPart.GetXDocument()
                                .Descendants(w + "body").FirstOrDefault();
                            body.AddFirst(
                                new XElement(w + "p",
                                    new XElement(w + "r",
                                        new XElement(w + "t", "Hello world"))));
                            wDoc.MainDocumentPart.PutXDocument();
                        }
                        Session["ByteArray"] = memoryStream.ToArray();
                    }
                }
                catch (Exception ex)
                {
                    lblMessage.Text = "ERROR: " + ex.Message.ToString();
                }
            else
            {
                lblMessage.Text = "You have not specified a file.";
            }
        }

        protected void btnDownload_Click(object sender, EventArgs e)
        {
            byte[] byteArray = (byte[])(Session["ByteArray"]);
            Response.Clear();
            Response.ContentType = "application/octet-stream";
            string fileName = (string)(Session["FileNameFromUser"]);
            Response.AddHeader("Content-Disposition",
                String.Format("attachment; filename={0}", fileName));
            Response.BinaryWrite(byteArray);
            Response.Flush();
            Response.End();
        }
    }

    public static class LocalExtensions
    {
        public static XDocument GetXDocument(this OpenXmlPart part)
        {

            XDocument partXDocument = part.Annotation<XDocument>();
            if (partXDocument != null)
                return partXDocument;
            using (Stream partStream = part.GetStream())
            {
                if (partStream.Length == 0)
                {
                    partXDocument = new XDocument();
                    partXDocument.Declaration = new XDeclaration("1.0", "UTF-8", "yes");
                }
                else
                    using (XmlReader partXmlReader = XmlReader.Create(partStream))
                        partXDocument = XDocument.Load(partXmlReader);
            }
            part.AddAnnotation(partXDocument);
            return partXDocument;
        }

        public static void PutXDocument(this OpenXmlPart part)
        {
            XDocument partXDocument = part.GetXDocument();
            if (partXDocument != null)
            {
                using (Stream partStream = part.GetStream(FileMode.Create, FileAccess.Write))
                using (XmlWriter partXmlWriter = XmlWriter.Create(partStream))
                    partXDocument.Save(partXmlWriter);
            }
        }
    }
}