Copying sitecore rendering to new template programmatically using renderingDefinition.ItemId?

Question

I have a custom sitecore button which changes the template of the current item, simple enough.

However as part of this I'm trying to also migrate the renderings of the old layout to a new layout if it's of a certain sublayout type by ItemId. However the ItemId that is returned is always null, the only value I get back from the RenderingDefinition is the UniqueId.

What am I doing wrong?

I have used this blog post as a guide.

The Code

public class ConvertToNewTemplateCommand : Command
{
protected void Run(ClientPipelineArgs args)
{
    if (!SheerResponse.CheckModified())
        return;

    Item item = Context.ContentDatabase.Items[args.Parameters["id"]];
    if (args.IsPostBack)
    {
        if (args.Result == "yes")
        {
            //Get current layout details
            var originalLayoutXml = item[FieldIDs.LayoutField];

            //Get new template
            TemplateItem hubTemplate = Context.ContentDatabase.GetTemplate("some guid...");
            //Change template  
            item.ChangeTemplate(hubTemplate);
            //Reset laytout
            ResetLayout(item);
            //Get reset layout
            var newLayoutXml = item[FieldIDs.LayoutField];

            //Add all the module containers to the new layout in the central column
            MoveModuleContainers(item, originalLayoutXml, newLayoutXml);
        }
    }
}

private void MoveModuleContainers(Item item, string oldXml, string newXml)
{
    var oldLayout = LayoutDefinition.Parse(oldXml);
    var newLayout = LayoutDefinition.Parse(newXml);

    bool updated = false;

    var oldRenderings = (oldLayout.Devices[0] as DeviceDefinition).Renderings;
    var newRenderings = (newLayout.Devices[0] as DeviceDefinition).Renderings;

    foreach (RenderingDefinition rendering in oldRenderings)
    {
        // Here is where the rendering.ItemID is always null
        if (rendering != null && !String.IsNullOrEmpty(rendering.ItemID) && new Guid(rendering.ItemID) == new Guid("matching guid..."))
        {
            rendering.Placeholder = "middlecolumn";
            newRenderings.Add(rendering);
            updated = true;
        }
    }

    if (updated)
    {
                   // Save item...
            }
}
}

Answer 1

I got onto Sitecore support in the end which informed me that I should use:

Sitecore.Data.Fields.LayoutField.GetFieldValue(item.Fields[Sitecore.FieldIDs.LayoutField])

instead of:

item[FieldIDs.LayoutField]

to get the items layoutField correctly. This results in the rendering values being parsed correctly and as they say the rest is history.