How to set extended file properties?

I need to set the Company field value for some Word/PDF documents. I am talking about the extended file properties (summary/author/title, etc.) you see under File Properties.

I know how to get them (by using shell32.dll class library). I assumed that I could also set them with the same class library, but it seems like writing extended properties is a little bit more difficult and shell32.dll doesn't allow that.

I found something about taglib-sharp, which seems to have an option to set extended properties, but I don't really understand how it works.

Solution

Add following NuGet packages to your project:

Microsoft.WindowsAPICodePack-Shell by Microsoft
Microsoft.WindowsAPICodePack-Core by Microsoft

Read and Write Properties

using Microsoft.WindowsAPICodePack.Shell;
using Microsoft.WindowsAPICodePack.Shell.PropertySystem;

string filePath = @"C:\temp\example.docx";
var file = ShellFile.FromFilePath(filePath);

// Read and Write:

string[] oldAuthors = file.Properties.System.Author.Value;
string oldTitle = file.Properties.System.Title.Value;

file.Properties.System.Author.Value = new string[] { "Author #1", "Author #2" };
file.Properties.System.Title.Value = "Example Title";

// Alternate way to Write:

ShellPropertyWriter propertyWriter =  file.Properties.GetPropertyWriter();
propertyWriter.WriteProperty(SystemProperties.System.Author, new string[] { "Author" });
propertyWriter.Close();

Important:

The file must be a valid one, created by the specific assigned software. Every file type has specific extended file properties and not all of them are writable.

If you right-click a file on desktop and cannot edit a property, you wont be able to edit it in code too.

Example:

Create txt file on desktop, rename its extension to docx. You can't edit its Author or Title property.
Open it with Word, edit and save it. Now you can.

So just make sure to use some try catch

Further Topic: MS Docs: Implementing Property Handlers