Tridion Update Multimedia Component Metadata XML using Core Service

UpdateMMCompMetadataXml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml.Linq;
using Tridion.ContentManager.CoreService.Client;

namespace FixMMCompMetadataField
{
    /// <summary>
    /// App to Update or remove Metadata fields of a Multimedia Component.  
    /// Background:  Somehow the Metadata of the MM Component had become corrupt 
    /// with a Category field referencing a non-existing keyword.  This caused
    /// publishing issues with DXA, as it attempts to render the fields of the 
    /// Component and fails.  
    /// 
    /// Thanks for the help from the following StackOverflow post:
    /// https://tridion.stackexchange.com/questions/11597/how-to-update-the-component-particular-field-node-using-core-service?utm_medium=organic&utm_source=google_rich_qa&utm_campaign=google_rich_qa
    /// </summary>
    public class Program
    {
        static string binding = "netTcp_201501";

        static void Main(string[] args)
        {
            string compUri = "tcm:4-123";
            List<FieldModel> fields = new List<FieldModel>()
            {
                new FieldModel()
                {
                    name = "metadataFieldName1",
                    value=""
                },
                new FieldModel()
                {
                    name = "metadataFieldName2",
                    value="Promoting Health"
                }
            };

            //   bool success = UpdateFields(compUri,fields);  // multiple-fields
            bool success = RemoveFields(compUri, fields);  // remove multiple-fields
        }

        public static bool RemoveFields(string componentUri, List<FieldModel> fields)
        {
            bool success = true;
            using (SessionAwareCoreServiceClient client = new SessionAwareCoreServiceClient(binding))
            {
                var component = (ComponentData)client.TryCheckOut(componentUri, null);

                try
                {
                    if (component.IsEditable.Value)
                    {
                        XElement xmlData;
                        XDocument doc;

                        doc = XDocument.Parse(component.Metadata);
                        xmlData = doc.Root;
                        var ns = xmlData.GetDefaultNamespace();

                        foreach (var field in fields)
                        {
                            if (xmlData.Descendants(ns + field.name).Any())
                            {
                                XElement itemToRemove = xmlData.Descendants(ns + field.name).SingleOrDefault();
                                itemToRemove.Remove();
                                //xmlData.Descendants(ns + field.name).SingleOrDefault().Value = field.value;
                                component.Metadata = doc.ToString();
                            }
                            else
                            {
                                // field not found
                            }
                        }


                        client.Update(component, null);
                    }
                    else
                    {
                        throw new Exception(string.Format("The Item '{0}' is checked out by some other user, can't be updated",
                            component.Title));
                    }
                }
                catch (Exception ex)
                {
                    client.UndoCheckOut(componentUri, false, null);
                    // todo - log
                    success = false;
                    throw;
                }
            }


            return success;
        }

        public static bool UpdateFields(string componentUri, List<FieldModel> fields)
        {
            bool success = true;

            using (SessionAwareCoreServiceClient client = new SessionAwareCoreServiceClient(binding))
            {
                var component = (ComponentData)client.TryCheckOut(componentUri, null);

                try
                {
                    if (component.IsEditable.Value)
                    {
                        XElement xmlData;
                        XDocument doc;

                        doc = XDocument.Parse(component.Metadata);
                        xmlData = doc.Root;
                        var ns = xmlData.GetDefaultNamespace();

                        foreach (var field in fields)
                        {
                            if (xmlData.Descendants(ns + field.name).Any())
                            {
                                xmlData.Descendants(ns + field.name).SingleOrDefault().Value = field.value;
                                component.Metadata = doc.ToString();
                            }
                            else
                            {
                                // field not found
                            }
                        }

                        client.Update(component, null);
                    }
                    else
                    {
                        throw new Exception(string.Format("The Item '{0}' is checked out by some other user, can't be updated",
                            component.Title));
                    }
                }
                catch (Exception ex)
                {
                    client.UndoCheckOut(componentUri, false, null);
                    // todo - log
                    success = false;
                    throw;
                }
            }

            return success;
        }
    }
    public class FieldModel
    {
        public string name { get; set; }
        public string value { get; set; }
    }
}