Maarten Balliauw {blog}

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Preview Word files (docx) in HTML using ASP.NET, OpenXML and LINQ to XML

Since an image (or even an example) tells more than any text will ever do, here's what I've created in the past few evening hours:

image

Live examples:

Want the source code? Download it here: WordVisualizer.zip (357.01 kb)

Want to know how?

If you want to know how I did this, let me first tell you why I created this. After searching Google for something similar, I found a Sharepoint blogger who did the same using a Sharepoint XSL transformation document called DocX2Html.xsl. Great, but this document can not be distributed without a Sharepoint license. The only option for me was to do something similar myself.

ASP.NET handlers

The main idea of this project was to be able to type in a URL ending in ".docx", which would then render a preview of the underlying Word document. Luckily, ASP.NET provides a system of creating HttpHandlers. A HttpHandler is the class instance which is called by the .NET runtime to process an incoming request for a specific extension. So let's trick ASP.NET into believing ".docx" is an extension which should be handled by a custom class...

Creating a custom handler

A custom handler can be created quite easily. Just create a new class, and make it implement the IHttpHandler interface:

[code:c#]

/// <summary>
/// Word document HTTP handler
/// </summary>

public class WordDocumentHandler : IHttpHandler
{
    #region IHttpHandler Members

    /// <summary>
    /// Is the handler reusable?
    /// </summary>

    public bool IsReusable
    {
        get { return true; }
    }

    /// <summary>
    /// Process request
    /// </summary>
    /// <param name="context">Current http context</param>

     public void ProcessRequest(HttpContext context)
    {
        // Todo...

        context.Response.Write("Hello world!");
    }

    #endregion
}

[/code]

Registering a custom handler

For ASP.NET to recognise our newly created handler, we must register it in Web.config:

image

Now if you are using IIS6, you should also register this extension to be handled by the .NET runtime:

image

In the application configuration, add the extension ".docx" and make it point to the following executable: C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspnet_isapi.dll

This should be it. Fire up your browser, browse to your web site and type anything.docx. You should see "Hello world!" appearing in a nice, white page.

OpenXML

As you may already know, Word 2007 files are OpenXML packages containg WordprocessingML markup. A .docx file can be opened using the System.IO.Packaging.Package class (which is available after adding a project reference to WindowsBase.dll).

The Package class is created for accessing any OpenXML package. This includes all Office 2007 file formats, but also custom OpenXML formats which you can implement for yourself. Unfortunately, if you want to use Package to access an Office 2007 file, you'll have to implement a lot of utility functions to get the right parts from the OpenXML container.

Luckily, Microsoft released an OpenXML SDK (CTP), which I also used in order to create this Word preview handler.

LINQ to XML

As you know, the latest .NET 3.5 release brought us something new & extremely handy: LINQ (Language Integrated Query). On Doug's blog, I read about Eric White's attempts to use LINQ to XML on OpenXML.

LINQ to OpenXML

For implementing my handler, I basically used similar code to Eric's to run query's on a Word document's contents. Here's an example which fetches all paragraphs in a Word document:

[code:c#]

using (WordprocessingDocument document = WordprocessingDocument.Open("test.docx", false))
{
    // Register namespace

    XNamespace w = "http://schemas.openxmlformats.org/wordprocessingml/2006/main";

    // Element shortcuts

    XName w_r = w + "r";
    XName w_ins = w + "ins";
    XName w_hyperlink = w + "hyperlink";

    // Load document's MainDocumentPart (document.xml) in XDocument

    XDocument xDoc = XDocument.Load(
        XmlReader.Create(
            new StreamReader(document.MainDocumentPart.GetStream())
        )
    );

    // Fetch paragraphs

    var paragraphs = from l_paragraph in xDoc
                    .Root
                    .Element(w + "body")
                    .Descendants(w + "p")
         select new
         {
             TextRuns = l_paragraph.Elements().Where(z => z.Name == w_r || z.Name == w_ins || z.Name == w_hyperlink)
         };

    // Write paragraphs

    foreach (var paragraph in paragraphs)
    {
        // Fetch runs

        var runs = from l_run in paragraph.Runs
                   select new
                   {
                       Text = l_run.Descendants(w + "t").StringConcatenate(element => (string)element)
                   };

        // Write runs

        foreach (var run in runs)
        {
            // Use run.Text to fetch a text string

            Console.Write(run.Text);
        }
    }
}

[/code]

Now if you run this code, you will notice a compilation error... This is due to the fact that I used an extension method StringConcatenate.

Extension methods

In the above example, I used an extension method named StringConcatenate. An extension method is, as the name implies, an "extension" to a known class. In the following example, find the extension for all IEnumerable<T> instances:

[code:c#]

public static class IEnumerableExtensions
{
    /// <summary>
    /// Concatenate strings
    /// </summary>
    /// <typeparam name="T">Type</typeparam>
    /// <param name="source">Source</param>
    /// <param name="func">Function delegate</param>
    /// <returns>Concatenated string</returns>

    public static string StringConcatenate<T>(this IEnumerable<T> source, Func<T, string> func)
    {
        StringBuilder sb = new StringBuilder();
        foreach (T item in source)
            sb.Append(func(item));
        return sb.ToString();
    }
}

[/code]

Lambda expressions

Another thing you may have noticed in my example code, is a lambda expression:

[code:c#]

z => z.Name == w_r || z.Name == w_ins || z.Name == w_hyperlink.

[/code]

A lambda expression is actually an anonymous method, which is called by the StringConcatenate extension method. Lambda expressions always accept a parameter, and return true/false. In this case, z is instantiated as an XNode, returning true/false depending on its Name property.

Wrapping things up...

If you read this whole blog post, you may have noticed that I extensively used C# 3.5's new language features. I combined these with OpenXML and ASP.NET to create a useful Word document preview handler. If you want the full source code, download it here: WordVisualizer.zip (357.01 kb).

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