C# code to replace the relationship between a provided SDL Web (Tridion) component and all its "where using" components with a reference (stub) to an asset originating from SDL Media Manager

update-where-using-components-with-ecl-stub-relationship.cs

private static void UpdateWhereUsingComponents(ICoreService coreServiceClient, SessionAwareEclServiceClient eclClient, ComponentData componentData, Dictionary<string, object> uploadInfo)
{
  Dictionary<string, string> stubInfo = null;
  try
  {
    stubInfo = eclClient.CreateOrGetStubUris(new List<string> { "ecl:5-mm-" + uploadInfo["distributionId"] + "-dist-file" });
  }
  catch(Exception exception)
  {
    log.Error("Error generating stub for image " + componentData.Id);
    log.Error(exception);
  }
  
  if (stubInfo == null || stubInfo.Count == 0)
    return;

  log.Info("Stub " + stubInfo.Values.First() + " generated for " + componentData.Id);
  
  // Create a filter
  UsingItemsFilterData usingItemsFilterData = new UsingItemsFilterData
  {
    BaseColumns = ListBaseColumns.Id, // to specify the detail in the XML
    IncludedVersions = VersionCondition.OnlyLatestVersions,
    ItemTypes = new[] { ItemType.Component }  // to specify certain items
  };
  
  SynchronizeOptions syncOptions = new SynchronizeOptions();
  syncOptions.SynchronizeFlags = SynchronizeFlags.FixNamespace | SynchronizeFlags.ApplyDefaultValuesForMissingMandatoryFields;
  ReadOptions readOptions = new ReadOptions();
  
  // Get the XML by calling .GetListXml on the client
  XElement usingXML = coreServiceClient.GetListXml(componentData.Id, usingItemsFilterData);
  XNamespace df = usingXML.Name.Namespace;
  IEnumerable<XElement> itemElements = usingXML.Elements(df + "Item");
  foreach (XElement itemElement in itemElements)
  {
    string usingItemTcmid = itemElement.FirstAttribute.Value;
    string usingItemPubId = usingItemTcmid.Split('-')[0];
    string multimediaLinkId = usingItemPubId + "-" + componentData.Id.Split('-')[1];
    string stubTcmId = usingItemPubId + "-" + stubInfo.Values.First().Split('-')[1];
    
    ComponentData usingItem = coreServiceClient.Read(usingItemTcmid, readOptions) as ComponentData;
    usingItem = (ComponentData)coreServiceClient.SynchronizeWithSchema(usingItem, syncOptions).SynchronizedItem;
    Boolean modified = false;

    if (!String.IsNullOrEmpty(usingItem.Content) && usingItem.Content.Contains(multimediaLinkId))
    {
      usingItem.Content = usingItem.Content.Replace(multimediaLinkId, stubTcmId);
      modified = true;
    }
    
    if (!String.IsNullOrEmpty(usingItem.Metadata) && usingItem.Metadata.Contains(multimediaLinkId))
    {
      usingItem.Metadata = usingItem.Metadata.Replace(multimediaLinkId, stubTcmId);
      modified = true;
    }
    
    if (modified)
    {
      try
      {
        coreServiceClient.CheckOut(usingItem.Id, true, readOptions);
        coreServiceClient.Save(usingItem, readOptions);
        coreServiceClient.CheckIn(usingItem.Id, true, "Updated by the migration tool", readOptions);
        log.Info("UPDATED RELATIONSHIP: " + usingItem.Id);
      }
      catch(Exception exception)
      {
        log.Error("Unable to update relationship in Tridion!");
        log.Error(exception);
        try
        {
          coreServiceClient.UndoCheckOut(usingItem.Id, true, readOptions);
        }
        catch(Exception undoCheckOutException)
        {
          log.Error("Unable to undo checkout!");
          log.Error(undoCheckOutException);
        }
        continue;
      }
    }
  }
}