Novacode.DocX.UpdateCorePropertyValue C# (CSharp) Method

        internal static void UpdateCorePropertyValue(DocX document, string corePropertyName, string corePropertyValue)
        {
            string matchPattern = string.Format(@"(DOCPROPERTY)?{0}\\\*MERGEFORMAT", corePropertyName).ToLower();
            foreach (XElement e in document.mainDoc.Descendants(XName.Get("fldSimple", w.NamespaceName)))
            {
                string attr_value = e.Attribute(XName.Get("instr", w.NamespaceName)).Value.Replace(" ", string.Empty).Trim().ToLower();

                if (Regex.IsMatch(attr_value, matchPattern))
                {
                    XElement firstRun = e.Element(w + "r");
                    XElement firstText = firstRun.Element(w + "t");
                    XElement rPr = firstText.Element(w + "rPr");

                    // Delete everything and insert updated text value
                    e.RemoveNodes();

                    XElement t = new XElement(w + "t", rPr, corePropertyValue);
                    Novacode.Text.PreserveSpace(t);
                    e.Add(new XElement(firstRun.Name, firstRun.Attributes(), firstRun.Element(XName.Get("rPr", w.NamespaceName)), t));
                }
            }

            #region Headers

            IEnumerable<PackagePart> headerParts = from headerPart in document.package.GetParts()
                                                   where (Regex.IsMatch(headerPart.Uri.ToString(), @"/word/header\d?.xml"))
                                                   select headerPart;
            foreach (PackagePart pp in headerParts)
            {
                XDocument header = XDocument.Load(new StreamReader(pp.GetStream()));

                foreach (XElement e in header.Descendants(XName.Get("fldSimple", w.NamespaceName)))
                {
                    string attr_value = e.Attribute(XName.Get("instr", w.NamespaceName)).Value.Replace(" ", string.Empty).Trim().ToLower();
                    if (Regex.IsMatch(attr_value, matchPattern))
                    {
                        XElement firstRun = e.Element(w + "r");

                        // Delete everything and insert updated text value
                        e.RemoveNodes();

                        XElement t = new XElement(w + "t", corePropertyValue);
                        Novacode.Text.PreserveSpace(t);
                        e.Add(new XElement(firstRun.Name, firstRun.Attributes(), firstRun.Element(XName.Get("rPr", w.NamespaceName)), t));
                    }
                }

                using (TextWriter tw = new StreamWriter(new PackagePartStream(pp.GetStream(FileMode.Create, FileAccess.Write))))
                    header.Save(tw);
            }
            #endregion

            #region Footers
            IEnumerable<PackagePart> footerParts = from footerPart in document.package.GetParts()
                                                   where (Regex.IsMatch(footerPart.Uri.ToString(), @"/word/footer\d?.xml"))
                                                   select footerPart;
            foreach (PackagePart pp in footerParts)
            {
                XDocument footer = XDocument.Load(new StreamReader(pp.GetStream()));

                foreach (XElement e in footer.Descendants(XName.Get("fldSimple", w.NamespaceName)))
                {
                    string attr_value = e.Attribute(XName.Get("instr", w.NamespaceName)).Value.Replace(" ", string.Empty).Trim().ToLower();
                    if (Regex.IsMatch(attr_value, matchPattern))
                    {
                        XElement firstRun = e.Element(w + "r");

                        // Delete everything and insert updated text value
                        e.RemoveNodes();

                        XElement t = new XElement(w + "t", corePropertyValue);
                        Novacode.Text.PreserveSpace(t);
                        e.Add(new XElement(firstRun.Name, firstRun.Attributes(), firstRun.Element(XName.Get("rPr", w.NamespaceName)), t));
                    }
                }

                using (TextWriter tw = new StreamWriter(new PackagePartStream(pp.GetStream(FileMode.Create, FileAccess.Write))))
                    footer.Save(tw);
            }
            #endregion
            PopulateDocument(document, document.package);
        }