MSDN Magazine - March 2008 - (Page 28)

• The custom property may exist, and its type matches the type of the new value. In this case, you simply set the property’s value. • The custom property may exist, but its type differs from the type of the new value. In this case, delete the property, and recreate it using the new type. (You could devise other means of resetting the type, but the code you’ll see here follows the same path if the property doesn’t yet exist, or it does exist and has the wrong type. Either way, the code creates a new element for the property). A sample set of custom properties might look like Figure 1.This particular document contains four custom properties: Author (Ken), Birthdate (1/1/1956), Chapter (2), revisions (5). Note that the XML content is scoped to the default namespace: http://schemas.openxmlformats.org/officeDocument/2006/custom-properties Figure 1 Some Custom Properties Ken 1956-01-01T06:00:00Z 2 5 The content also includes a non-default namespace that it uses to describe the property types: vt=”http://schemas.openxmlformats.org/officeDocument/2006/docPropsVTypes” Any code you write that works with this part needs to respect and maintain those namespaces or Word 2007 simply won’t load your document (a fact I learned the hard way, after many failed attempts.) Each property element contains an fmtid attribute with the same GUID value ({D5CDD505-2E9C-101B-9397-08002B2CF9AE}). Each property also includes a pid attribute, which must be a numeric value, starting with 2, and increasing in value. Although Word 2007 allows you to skip values (you can have properties with pid values of 2, 3, and 5, for example), these values cannot be the same, and they must appear in numeric order. Finally, each property includes a name attribute containing the name of the property. Within each property element, you must add an element that contains the value of the property. The element name, in each case, indicates the type of value the property contains. The sample code provides an enumeration with a value representing each of these types: Public Enum PropertyTypes YesNo Text DateTime NumberInteger NumberDouble End Enum port namespaces in this manner makes coding easier, but it does force one limitation: you can define only one default namespace per file. If you want to include XML code that uses a different default namespace, you’ll need to place that code in a separate file. Of course, because you can split a single class into multiple files by creating partial classes, this isn’t a restriction except with regard to file management in your project.) In order to set the document property, you’ll need to create a method that can be called like this: WDSetCustomProperty(“C:\YourDocument.docx”, “PropertyName”, _ “PropertyValue”, PropertyTypes.Text) In the XML content, these types correspond to bool, lpwstr, filetime, i4, and r8, respectively. Each of these type names belongs to the XML namespace which has been assigned to the alias vt. In order to make it easy to interact with XML namespaces, Visual Basic overrides the behavior of the file-level Imports statement. You can specify abbreviations for namespaces at the top of a file and use those abbreviations within the file. The sample code uses the following Imports statements: Imports System.IO Imports Packaging = Microsoft.Office.DocumentFormat.OpenXml.Packaging Imports Imports If the property value you supply doesn’t match the PropertyTypes enumerated value you specified, the code should raise an exception and return without attempting to perform any operation. Throughout the sample code, you’ll see examples of features that are new in Visual Studio 2008. Among other features that I’ll call out specifically, you’ll see code that uses implicit type declaration. Rather than specifying a type for each variable, Visual Basic uses type inference to infer the type at compile time. This means that you can write code like this: Using wdPackage = _ Packaging.WordprocessingDocument.Open(docName, True) End Using The explicit declaration would look like this: Using wdPackage As Packaging.WordprocessingDocument = _ Packaging.WordprocessingDocument.Open(docName, True) ‘ Code removed here. End Using I’ve used the Packaging alias so that it’s clear within the code when I’m using code from the 2007 Office system Open XML SDK. The code also includes Imports statements for the default namespace and the namespace with the alias vt. (The fact that you can im28 msdnmagazine Advanced Basics Not specifying the exact type doesn’t detract from the readability of the code, and Visual Basic compiles both versions in the same way. (This feature is controlled by the Option Infer file-level option, which is set to On by default.) Investigating the Code Now I’ll investigate the sample code, explaining each block. The entire WDSetCustomProperty procedure is available in the code

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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