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How to: Add a new document part to a package (Open XML SDK)

Last modified: July 27, 2012

Applies to: Office 2013 | Open XML

In this article
Packages and Document Parts
Getting a WordprocessingDocument Object
Basic Structure of a WordProcessingML Document
How the Sample Code Works
Sample Code

This topic shows how to use the classes in the Open XML SDK 2.5 for Office to add a document part (file) to a word processing document programmatically.

The following assembly directives are required to compile the code in this topic.

using System.IO;
using DocumentFormat.OpenXml.Packaging;

An Open XML document is stored as a package, whose format is defined by ISO/IEC 29500-2. The package can have multiple parts with relationships between them. The relationship between parts controls the category of the document. A document can be defined as a word-processing document if its package-relationship item contains a relationship to a main document part. If its package-relationship item contains a relationship to a presentation part it can be defined as a presentation document. If its package-relationship item contains a relationship to a workbook part, it is defined as a spreadsheet document. In this how-to topic, you will use a word-processing document package.

The code starts with opening a package file by passing a file name to one of the overloaded Open() methods of the DocumentFormat.OpenXml.Packaging.WordprocessingDocument that takes a string and a Boolean value that specifies whether the file should be opened for editing or for read-only access. In this case, the Boolean value is true specifying that the file should be opened in read/write mode.

using (WordprocessingDocument wordDoc = WordprocessingDocument.Open(document, true))
    // Insert other code here.

The using statement provides a recommended alternative to the typical .Create, .Save, .Close sequence. It ensures that the Dispose method (internal method used by the Open XML SDK to clean up resources) is automatically called when the closing brace is reached. The block that follows the using statement establishes a scope for the object that is created or named in the using statement, in this case wordDoc. Because the WordprocessingDocument class in the Open XML SDK automatically saves and closes the object as part of its System.IDisposable implementation, and because the Dispose method is automatically called when you exit the block; you do not have to explicitly call Save and Close─as long as you use using.

The basic document structure of a WordProcessingML document consists of the document and body elements, followed by one or more block level elements such as p, which represents a paragraph. A paragraph contains one or more r elements. The r stands for run, which is a region of text with a common set of properties, such as formatting. A run contains one or more t elements. The t element contains a range of text. The WordprocessingML markup for the document that the sample code creates is shown in the following code example.

<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main">
        <w:t>Create text in body - CreateWordprocessingDocument</w:t>

Using the Open XML SDK 2.5, you can create document structure and content using strongly-typed classes that correspond to WordprocessingML elements. You can find these classes in the DocumentFormat.OpenXml.Wordprocessing namespace. The following table lists the class names of the classes that correspond to the document, body, p, r, and t elements,

WordprocessingML Element

Open XML SDK 2.5 Class




The root element for the main document part.



The container for the block level structures such as paragraphs, tables, annotations, and others specified in the ISO/IEC 29500 specification.



A paragraph.



A run.



A range of text.

After opening the document for editing, in the using statement, as a WordprocessingDocument object, the code creates a reference to the MainDocumentPart part and adds a new custom XML part. It then reads the contents of the external file that contains the custom XML and writes it to the CustomXmlPart part.

Note Note

To use the new document part in the document, add a link to the document part in the relationship part for the new part.

MainDocumentPart mainPart = wordDoc.MainDocumentPart;
CustomXmlPart myXmlPart = mainPart.AddCustomXmlPart(CustomXmlPartType.CustomXml);

using (FileStream stream = new FileStream(fileName, FileMode.Open))

The following code adds a new document part that contains custom XML from an external file and then populates the part. To call the AddCustomXmlPart method in your program, you can use the following example that modifies the file "myPkg2.docx" by adding a new document part to it.

string document = @"C:\Users\Public\Documents\myPkg2.docx";
string fileName = @"C:\Users\Public\Documents\myXML.xml";
AddNewPart(document, fileName);


Before you run the program, change the Word file extension from .docx to .zip, and view the content of the zip file. Then change the extension back to .docx and run the program. After running the program, change the file extension again to .zip and view its content. You will see an extra folder named "customXML." This folder contains the XML file that represents the added part

Following is the complete code example in both C# and Visual Basic.

// To add a new document part to a package.
public static void AddNewPart(string document, string fileName)
    using (WordprocessingDocument wordDoc = WordprocessingDocument.Open(document, true))
        MainDocumentPart mainPart = wordDoc.MainDocumentPart;

        CustomXmlPart myXmlPart = mainPart.AddCustomXmlPart(CustomXmlPartType.CustomXml);

        using (FileStream stream = new FileStream(fileName, FileMode.Open))

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