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Delete all the comments by an author from all the slides in a presentation

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This topic shows how to use the classes in the Open XML SDK for Office to delete all of the comments by a specific author in a presentation programmatically.

Getting a PresentationDocument Object

In the Open XML SDK, the PresentationDocument class represents a presentation document package. To work with a presentation document, first create an instance of the PresentationDocument class, and then work with that instance. To create the class instance from the document call the Open(String, Boolean) method that uses a file path, and a Boolean value as the second parameter to specify whether a document is editable. To open a document for read/write, specify the value true for this parameter as shown in the following using statement. In this code, the fileName parameter is a string that represents the path for the file from which you want to open the document, and the author is the user name displayed in the General tab of the PowerPoint Options.

    public static void DeleteCommentsByAuthorInPresentation(string fileName, string author)
    {
        using (PresentationDocument doc = PresentationDocument.Open(fileName, true))
        {
            // Insert other code here.
        }

The using statement provides a recommended alternative to the typical .Open, .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 doc.

Basic Presentation Document Structure

The basic document structure of a PresentationML document consists of a number of parts, among which is the main part that contains the presentation definition. The following text from the ISO/IEC 29500 specification introduces the overall form of a PresentationML package.

The main part of a PresentationML package starts with a presentation root element. That element contains a presentation, which, in turn, refers to a slide list, a slide master list, a notes master list, and a handout master list. The slide list refers to all of the slides in the presentation; the slide master list refers to the entire slide masters used in the presentation; the notes master contains information about the formatting of notes pages; and the handout master describes how a handout looks.

A handout is a printed set of slides that can be provided to an audience.

As well as text and graphics, each slide can contain comments and notes, can have a layout, and can be part of one or more custom presentations. A comment is an annotation intended for the person maintaining the presentation slide deck. A note is a reminder or piece of text intended for the presenter or the audience.

Other features that a PresentationML document can include the following: animation, audio, video, and transitions between slides.

A PresentationML document is not stored as one large body in a single part. Instead, the elements that implement certain groupings of functionality are stored in separate parts. For example, all comments in a document are stored in one comment part while each slide has its own part.

© ISO/IEC29500: 2008.

The following XML code example represents a presentation that contains two slides denoted by the IDs 267 and 256.

    <p:presentation xmlns:p="…" … > 
       <p:sldMasterIdLst>
          <p:sldMasterId
             xmlns:rel="https://…/relationships" rel:id="rId1"/>
       </p:sldMasterIdLst>
       <p:notesMasterIdLst>
          <p:notesMasterId
             xmlns:rel="https://…/relationships" rel:id="rId4"/>
       </p:notesMasterIdLst>
       <p:handoutMasterIdLst>
          <p:handoutMasterId
             xmlns:rel="https://…/relationships" rel:id="rId5"/>
       </p:handoutMasterIdLst>
       <p:sldIdLst>
          <p:sldId id="267"
             xmlns:rel="https://…/relationships" rel:id="rId2"/>
          <p:sldId id="256"
             xmlns:rel="https://…/relationships" rel:id="rId3"/>
       </p:sldIdLst>
           <p:sldSz cx="9144000" cy="6858000"/>
       <p:notesSz cx="6858000" cy="9144000"/>
    </p:presentation>

Using the Open XML SDK, you can create document structure and content using strongly-typed classes that correspond to PresentationML elements. You can find these classes in the DocumentFormat.OpenXml.Presentation namespace. The following table lists the class names of the classes that correspond to the sld, sldLayout, sldMaster, and notesMaster elements.

PresentationML Element Open XML SDK Class Description
sld Slide Presentation Slide. It is the root element of SlidePart.
sldLayout SlideLayout Slide Layout. It is the root element of SlideLayoutPart.
sldMaster SlideMaster Slide Master. It is the root element of SlideMasterPart.
notesMaster NotesMaster Notes Master (or handoutMaster). It is the root element of NotesMasterPart.

The Structure of the Comment Element

The following text from the ISO/IEC 29500 specification introduces comments in a presentation package.

A comment is a text note attached to a slide, with the primary purpose of allowing readers of a presentation to provide feedback to the presentation author. Each comment contains an unformatted text string and information about its author, and is attached to a particular location on a slide. Comments can be visible while editing the presentation, but do not appear when a slide show is given. The displaying application decides when to display comments and determines their visual appearance.

© ISO/IEC29500: 2008.

The following XML element specifies a single comment attached to a slide. It contains the text of the comment (text), its position on the slide (pos), and attributes referring to its author (authorId), date and time (dt), and comment index (idx).

    <p:cm authorId="0" dt="2006-08-28T17:26:44.129" idx="1">
        <p:pos x="10" y="10"/>
        <p:text>Add diagram to clarify.</p:text>
    </p:cm>

The following table lists the definitions of the members and attributes of the cm (comment) element.

Member/Attribute Definition
authorId Refers to the ID of an author in the comment author list for the document.
dt The date and time this comment was last modified.
idx An identifier for this comment that is unique within a list of all comments by this author in this document. An author's first comment in a document has index 1.
pos The positioning information for the placement of a comment on a slide surface.
text Comment's text content.
extLst Specifies the extension list with modification ability within which all future extensions of element type ext are defined. The extension list along with corresponding future extensions is used to extend the storage capabilities of the PresentationML framework. This allows for various new kinds of data to be stored natively within the framework.

The following XML schema example defines the members of the cm element in addition to the required and optional attributes.

    <complexType name="CT_Comment">
       <sequence>
           <element name="pos" type="a:CT_Point2D" minOccurs="1" maxOccurs="1"/>
           <element name="text" type="xsd:string" minOccurs="1" maxOccurs="1"/>
           <element name="extLst" type="CT_ExtensionListModify" minOccurs="0" maxOccurs="1"/>
       </sequence>
       <attribute name="authorId" type="xsd:unsignedInt" use="required"/>
       <attribute name="dt" type="xsd:dateTime" use="optional"/>
       <attribute name="idx" type="ST_Index" use="required"/>
    </complexType>

How the Sample Code Works

After opening the presentation document for read/write access and instantiating the PresentationDocument class, the code gets the specified comment author from the list of comment authors.

    // Get the specifed comment author.
    IEnumerable<CommentAuthor> commentAuthors = 
        doc.PresentationPart.CommentAuthorsPart.CommentAuthorList.Elements<CommentAuthor>()
        .Where(e => e.Name.Value.Equals(author));

By iterating through the matching authors and all the slides in the presentation the code gets all the slide parts, and the comments part of each slide part. It then gets the list of comments by the specified author and deletes each one. It also verifies that the comment part has no existing comment, in which case it deletes that part. It also deletes the comment author from the comment authors part.

    // Iterate through all the matching authors.
    foreach (CommentAuthor commentAuthor in commentAuthors)
    {
        UInt32Value authorId = commentAuthor.Id;

        // Iterate through all the slides and get the slide parts.
        foreach (SlidePart slide in doc.PresentationPart.SlideParts)
        {
            SlideCommentsPart slideCommentsPart = slide.SlideCommentsPart;
            // Get the list of comments.
            if (slideCommentsPart != null && slide.SlideCommentsPart.CommentList != null)
            {
                IEnumerable<Comment> commentList = 
                    slideCommentsPart.CommentList.Elements<Comment>().Where(e => e.AuthorId == authorId.Value);
                List<Comment> comments = new List<Comment>();
                comments = commentList.ToList<Comment>();

                foreach (Comment comm in comments)
                {
                    // Delete all the comments by the specified author.
                    slideCommentsPart.CommentList.RemoveChild<Comment>(comm);
                }

                // If the commentPart has no existing comment.
                if (slideCommentsPart.CommentList.ChildElements.Count == 0)
                    // Delete this part.
                    slide.DeletePart(slideCommentsPart);
            }
        }
        // Delete the comment author from the comment authors part.
        doc.PresentationPart.CommentAuthorsPart.CommentAuthorList.RemoveChild<CommentAuthor>(commentAuthor);
    }

Sample Code

The following method takes as parameters the source presentation file name and path and the name of the comment author whose comments are to be deleted. It finds all the comments by the specified author in the presentation and deletes them. It then deletes the comment author from the list of comment authors.

You can use the following example to call the DeleteCommentsByAuthorInPresentation method to remove the comments of the specified author from the presentation file, myppt5.pptx.

    string fileName = @"C:\Users\Public\Documents\myppt5.pptx";
    string author = "Katie Jordan";
    DeleteCommentsByAuthorInPresentation(fileName, author);

Note

To get the exact author's name, open the presentation file and click the File menu item, and then click Options. The PowerPoint Options window opens and the content of the General tab is displayed. The author's name must match the User name in this tab.

The following is the complete sample code in both C# and Visual Basic.

using DocumentFormat.OpenXml;
using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Presentation;
using System.Collections.Generic;
using System.Linq;

DeleteCommentsByAuthorInPresentation(args[0], args[1]);

// Remove all the comments in the slides by a certain author.
static void DeleteCommentsByAuthorInPresentation(string fileName, string author)
{
    using (PresentationDocument doc = PresentationDocument.Open(fileName, true))
    {
        // Get the specified comment author.
        IEnumerable<CommentAuthor>? commentAuthors = doc.PresentationPart?.CommentAuthorsPart?.CommentAuthorList?.Elements<CommentAuthor>()
            .Where(e => e.Name is not null && e.Name.Value is not null && e.Name.Value.Equals(author));

        if (commentAuthors is null)
        {
            return;
        }

        // Iterate through all the matching authors.
        foreach (CommentAuthor commentAuthor in commentAuthors)
        {
            UInt32Value? authorId = commentAuthor.Id;
            IEnumerable<SlidePart>? slideParts = doc.PresentationPart?.SlideParts;

            // If there's no author ID or slide parts, return.
            if (authorId is null || slideParts is null)
            {
                return;
            }

            // Iterate through all the slides and get the slide parts.
            foreach (SlidePart slide in slideParts)
            {
                SlideCommentsPart? slideCommentsPart = slide.SlideCommentsPart;

                // Get the list of comments.
                if (slideCommentsPart is not null && slide.SlideCommentsPart?.CommentList is not null)
                {
                    IEnumerable<Comment> commentList = slideCommentsPart.CommentList.Elements<Comment>().Where(e => e.AuthorId is not null && e.AuthorId == authorId.Value);
                    List<Comment> comments = new List<Comment>();
                    comments = commentList.ToList<Comment>();

                    foreach (Comment comm in comments)
                    {
                        // Delete all the comments by the specified author.

                        slideCommentsPart.CommentList.RemoveChild<Comment>(comm);
                    }

                    // If the commentPart has no existing comment.
                    if (slideCommentsPart.CommentList.ChildElements.Count == 0)
                        // Delete this part.
                        slide.DeletePart(slideCommentsPart);
                }
            }
            // Delete the comment author from the comment authors part.
            doc.PresentationPart?.CommentAuthorsPart?.CommentAuthorList.RemoveChild(commentAuthor);
        }
    }
}