Set custom document properties with Word interop

Question

I want to set some custom document properties of a word document I\'m creating in my C# code. To do this, I followed this MSDN article and came up with this code:

Answer 1

SliverNinja's answer above is correct. I forgot you had to .Add to the collection until I ported some old VB code. I had to set and read a bunch of doc properties, so here are a couple extension methods to read/write from either the BuiltInDocumentProperties or the CustomDocumentProperties in Word. This is NetOffice code, but you can convert it to VSTO by just changing the using statements.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NetOffice.OfficeApi;
using NetOffice.OfficeApi.Enums;
using NetOffice.WordApi;

namespace PalabraAddin {
    public static class ExtDocument {

        public static T GetCustomProperty(this Document doc, string name, T defaultValue) {
            return doc.GetProperty(doc.CustomDocumentProperties, name, defaultValue);
        }

        public static T GetBuiltInProperty(this Document doc, string name, T defaultValue) {
            return doc.GetProperty(doc.BuiltInDocumentProperties, name, defaultValue);
        }

        public static T SetCustomProperty(this Document doc, string name, T value) {
            return doc.SetProperty(doc.CustomDocumentProperties, name, value);
        }

        public static T SetBuiltInProperty(this Document doc, string name, T value) {
            return doc.SetProperty(doc.BuiltInDocumentProperties, name, value);
        }

        public static T GetProperty(this Document doc, object collection, string name, T defaultValue) {
            var properties = (DocumentProperties) collection;
            foreach (var prop in properties.Where(prop => prop.Name == name))
                return (T) prop.Value;
            return defaultValue;
        }

        public static T SetProperty(this Document doc, object collection, string name, T value) {
            var properties = (DocumentProperties) collection;
            foreach (var prop in properties.Where(prop => prop.Name == name)) {
                if (!((T) prop.Value).Equals(value))
                    prop.Value = value;
                return value;
            }

            MsoDocProperties propType;
            if (value is Boolean) 
                propType = MsoDocProperties.msoPropertyTypeBoolean;
            else if (value is DateTime)
                propType = MsoDocProperties.msoPropertyTypeDate;
            else if (value is double || value is Single)
                propType = MsoDocProperties.msoPropertyTypeFloat;
            else if (value is int)
                propType = MsoDocProperties.msoPropertyTypeNumber;
            else 
                propType = MsoDocProperties.msoPropertyTypeString;

            properties.Add(name, false, propType, value);
            return value;
        }
    }
}