MSDN Magazine - March 2008 - (Page 31)

mation. For any specific namespaces that the code requires, you’ll need to include the information in the XML literal, as you just saw for the vt namespace. This XML content includes a replacement token for all the existing property elements and uses the new If function in Visual Basic. The If function, unlike the older IIf function, doesn’t have the and determining which to return, the If function evaluates its parameters from left to right. This bypasses an error that would have occurred in this case using the IIf function (if propertiesNode was Nothing, the IIf function would still have attempted to retrieve its Elements property, causing an exception). After outputting the existing property elements (if they exist), the code outputs the new property node. This results in customDoc containing the full XML content of the custom properties part. There is one final challenge left—saving the part back to file storage. The XDocument class and the SDK provide the solution here. You can call the Save method of the XDocument object, customDoc, which allows you to specify a stream into which to write the XML content. Conveniently, the CustomFilePropertiesPart class provides a GetStream method, returning the stream corresponding to the part’s storage within the package: customDoc.Save(New StreamWriter( _ customPropsPart.GetStream( _ FileMode.Create, FileAccess.Write))) Wrapping It Up Although this seems like a lot of code to satisfy a rather simple goal, once you remove the comments and the code that formats the parameters, the code that actually performs the work with the document is relatively short. Compare it to the code in the original snippet, and you’ll have to agree that using the Microsoft SDK for 2007 Office system Open XML Formats and LINQ to XML in Visual Basic dramatically simplifies the process of working with 2007 Office system Open XML documents. If you search the Web for LINQ to XML, you’ll find many documents to help get over the hurdle of working with XML using LINQ. Although not specific to Visual Basic, the document “.NET Language-Integrated Query for XML Data” (msdn2.microsoft.com/bb308960) covers much of what you’ll need to know. You’ll also find the Visual Basic team’s blog (blogs.msdn.com/vbteam) to be a good source. I’d love to have the bandwidth to go back and revise all 40 of the original code snippets to use these new technologies, but it’s not likely I’ll have time to do that. You can, however, take what you’ve learned here and use it to modify any code you have written that interacts with the 2007 Office system Open XML File Formats. You’ll certainly reduce the complexity and the volume of code in doing so. Code download available at msdn.microsoft.com/msdnmag/code08.aspx. Send your questions and comments for Ken to basics@microsoft.com. Ken Getz is a Senior Consultant with MCW Technologies, and a courseware author for AppDev (www.appdev.com). He is coauthor of ASP .NET Developers Jumpstart, Access Developer’s Handbook, and VBA Developer’s Handbook, 2nd Edition. Reach him at keng@mcwtech.com. Advanced Basics march2008 31 http://msdn2.microsoft.com/bb308960 http://msdn2.microsoft.com/bb308960 http://blogs.msdn.com/vbteam http://msdn.microsoft.com/msdnmag/code08.aspx http://www.datadynamics.com http://www.appdev.com

Table of Contents Feed for the Digital Edition of MSDN Magazine - March 2008

MSDN Magazine - March 2008 Contents Toolbox CLR Inside Out Data Points Advanced Basics Office Space Introducing ASP.NET MVC Loosen Up CI Server Performance Office Development Test Run Security Briefs Extreme ASP.NET Foundations .NET Matters {End Bracket}

MSDN Magazine - March 2008

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