title: How to "Insert text from file" using OpenXml SDK 2.0
body: <p>Using Word 2010 GUI, there is an option to "Insert text from file...", which does exactly that: It insert the text in the main part of a document to the current location in your document.</p>
  
  <p>I would like to do the same using C# and the OpenXml SDK 2.0</p>
  
  <pre><code>using (var mainDocument = WordprocessingDocument.Open("MainFile.docx", true);
  {
      var mainPart = mainDocument.MainDocumentPart;
      var bookmarkStart = mainPart
                          .Document
                          .Body
                          .Descendants&lt;BookmarkStart&gt;()
                          .SingleOrDefault(b =&gt; b.Name == "ExtraContentBookmark");
      var extraContent = GetTextFromFile("ExtraFile.docx");
  
      bookmarkStart.InsertAfterSelf(extraContent);
  }
  </code></pre>
  
  <p>I have tried using plain Xml (XElement), using OpenXmlElement (MainDocumentPart.Document.Body.Descendants), and using AltChunk. Every alternative so far has yielded a non-conformant docx-file.</p>
  
  <p>What should the method <code>GetTextFromFile</code> look like?</p>