How to Rename a Bookmark in a Word Document using C# in ASP.NET Core?

Syncfusion® Essential® DocIO is a .NET Word library used to create, read, edit, and convert Word documents programmatically without Microsoft Word or interop dependencies. Using this library, you can rename a bookmark in a Word document using C#.

Steps to rename a bookmark in a Word document:

1. Create a new .NET Core console application project.
   
   
2. Install the Syncfusion.DocIO.Net.Core NuGet package as a reference to your project from NuGet.org.
   
   

3. Include the following namespaces in the Program.cs file.
   C#

using Syncfusion.DocIO.DLS;
using Syncfusion.DocIO; 

4. Use the following code example to rename a bookmark in a Word document.
   C#

using (FileStream fileStreamPath = new FileStream(Path.GetFullPath(@"Data/Template.docx"), FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
    //Opens an existing Word document.
    using (WordDocument document = new WordDocument(fileStreamPath, FormatType.Automatic))
    {
        //Rename Bookmark
        RenameBookmark(document, "Northwind", "New_Bookmark");
        //Creates file stream.
        using (FileStream outputFileStream = new FileStream(Path.GetFullPath(@"Output/Result.docx"), FileMode.Create, FileAccess.ReadWrite))
        {
            //Saves the Word document to file stream.
            document.Save(outputFileStream, FormatType.Docx);
        }
    }
}

5. Use the following code example to rename the bookmark in the given document.
   C#

private static void RenameBookmark(WordDocument document, string existingBookmarkName, string newBookmarkName)
{
    //Gets the bookmark instance by using FindByName method of BookmarkCollection with bookmark name
    Bookmark bookmark = document.Bookmarks.FindByName(existingBookmarkName);
    // No bookmark found, return immediately
    if (bookmark == null)
        return;
    // Variables to store the index positions of the bookmark start and end within their respective owners
    int startIndex = -1;
    int endIndex = -1;
    // Create new bookmark start and end markers with the replacement name
    BookmarkStart newBookmarkStart = new BookmarkStart(document, newBookmarkName);
    BookmarkEnd newBookmarkEnd = new BookmarkEnd(document, newBookmarkName);

    // Determine the owner and index for the bookmark start.
    // The bookmark start may be inside a WParagraph (as a child entity)
    // or inside an InlineContentControl (as a paragraph item).
    if (bookmark.BookmarkStart != null && bookmark.BookmarkStart.Owner is WParagraph)
    {
        WParagraph startParagraph = bookmark.BookmarkStart.Owner as WParagraph;
        // Find the index of the old bookmark start in the paragraph's child entities
        startIndex = startParagraph.ChildEntities.IndexOf(bookmark.BookmarkStart);
        // Insert the new bookmark end at the same index.
        startParagraph.ChildEntities.Insert(startIndex, newBookmarkStart);
    }
    else if (bookmark.BookmarkStart != null && bookmark.BookmarkStart.Owner is InlineContentControl)
    {
        InlineContentControl startICC = bookmark.BookmarkStart.Owner as InlineContentControl;
        // Find the index of the old bookmark end in the ICC's paragraph items
        startIndex = startICC.ParagraphItems.IndexOf(bookmark.BookmarkStart);
        // Insert the new bookmark end at the same index.
        startICC.ParagraphItems.Insert(startIndex, newBookmarkStart);
    }
    // Determine the owner and index for the bookmark end.
    // Similar to start, the end could be in a paragraph or inline content control.
    if (bookmark.BookmarkEnd != null && bookmark.BookmarkEnd.Owner is WParagraph)
    {
        WParagraph endParagraph = bookmark.BookmarkEnd.Owner as WParagraph;
        // Find the index of the old bookmark end in the paragraph's child entities
        endIndex = endParagraph.ChildEntities.IndexOf(bookmark.BookmarkEnd);
        // Insert the new bookmark end at the same index.
        endParagraph.ChildEntities.Insert(endIndex, newBookmarkEnd);
    }
    else if (bookmark.BookmarkEnd != null && bookmark.BookmarkEnd.Owner is InlineContentControl)
    {
        InlineContentControl endICC = bookmark.BookmarkEnd.Owner as InlineContentControl;
        // Find the index of the old bookmark end in the ICC's paragraph items
        endIndex = endICC.ParagraphItems.IndexOf(bookmark.BookmarkEnd);
        // Insert the new bookmark end at the same index.
        endICC.ParagraphItems.Insert(endIndex, newBookmarkEnd);
    }
    //Removes the bookmark from Word document.
    document.Bookmarks.Remove(bookmark);
}

You can download a complete working sample to rename a bookmark in a Word document from GitHub

Take a moment to peruse the documentation where you can find basic Word document processing options along with features like mail merge, merge, split, and compare Word documents, find and replace text in the Word document, protect the Word documents, and most importantly, the PDF and Image conversions with code examples.

Conclusion

I hope you enjoyed learning about how to rename a bookmark in a Word document.

You can refer to our ASP.NET Core DocIO feature tour page to know about its other groundbreaking feature representations and documentation, and how to quickly get started with configuration specifications. You can also explore our ASP.NET Core DocIO example to understand how to create and manipulate data.

For current customers, you can check out our components from the License and Downloads page. If you are new to Syncfusion®, you can try our 30-day free trial to check out our other controls.

If you have any queries or require clarifications, please let us know in the comments section below. You can also contact us through our support forums, Direct-Trac, or feedback portal. We are always happy to assist you!