We set the properties in the OrderFinalized handler

public override void Handle(OrderFinalizedNotification evt)
{
    this.logger.LogInformation("Order {OrderNumber} finalized", evt.Order.OrderNumber);

    var hasDigitalProducts = evt.Order.OrderLines.Any(x => x.Sku == Product.Sku.Digital);
    var hasPhysicalProducts = evt.Order.OrderLines.Any(x => x.Sku == Product.Sku.Physical);
    var invoiceNumber = Task.Run(() => this.invoiceDataReaderService.GetIdAsync(evt.Order.Id)).GetAwaiter().GetResult();

    this.vendrApi.Uow.Execute(uow =>
    {
        var processingOrderState =
            this.vendrApi.GetOrderStatus(evt.Order.StoreId, Constants.OrderStates.Processing);

        var order = evt.Order
            .AsWritable(uow)
            .SetProperty(Constants.OrderHasDigitalProductsPropertyAlias, hasDigitalProducts.ToString())
            .SetProperty(Constants.OrderHasPhysicalProductsPropertyAlias, hasPhysicalProducts.ToString())
            .SetProperty(Constants.InvoiceNumberPropertyAlias, invoiceNumber.ToString())
            .SetOrderStatus(processingOrderState);

        this.vendrApi.SaveOrder(order);

        uow.Complete();
    });

    this.backgroundJobSchedulingService.Enqueue(new ProcessOrderBackgroundJobData { OrderNumber = evt.Order.OrderNumber });
}

This queues a background job for processing the order.

public async Task<bool> PerformAsync(ProcessOrderBackgroundJobData jobData)
{
    try
    {
        this.logger.LogInformation("Start processing order {OrderNumber}", jobData.OrderNumber);

        var store = this.venderApi.GetStore(Constants.StoreAlias);

        var order = this.venderApi.GetOrder(store.Id, jobData.OrderNumber);

        // Need to use AsWritable to fetch the latest DB version of the object.
        this.venderApi.Uow.Execute(uow =>
        {
            order = order.AsWritable(uow);

            uow.Complete();
        });

        var hasDigitalProducts = order.Properties[Constants.OrderHasDigitalProductsPropertyAlias].Value
            .TryConvertTo<bool>().ResultOr(false);

        var hasPhysicalProducts = order.Properties[Constants.OrderHasPhysicalProductsPropertyAlias].Value
            .TryConvertTo<bool>().ResultOr(false);
        ...

It basically will break on hasDigitalProducts because the order we fetched does not yet have the additional properties that we assigned in the OrderFinalized handler.

The only solution is to asign order.AsWritable(uow); to the order object, which makes it fetch the latest version.

Hmm, this should be ok.

Vendr maintains a cache, from which GetOrder will use, but AsWritable will re-fetch from the database. When working with a writable order, updates are recorded in a temporary cache and the calling uow.Complete() should copy those updates back to the global cache so closing the uow in the handler, should copy it's property changes back to the global cache, and then when the background task runs it should fetch the cached values.

There must be something else to this as when I run the following code, the property is updated as expected

var store = CurrentPage.Value<StoreReadOnly>("store");
var order = _vendrApi.GetOrCreateCurrentOrder(store.Id);
var value = DateTime.UtcNow.Ticks.ToString();

_vendrApi.Uow.Execute(uow =>
{
    var wo = order.AsWritable(uow)
        .SetProperty("TEST", value);

    _vendrApi.SaveOrder(wo);

    uow.Complete();

});

order = _vendrApi.GetOrder(store.Id, order.OrderNumber);

var val = order.Properties["TEST"]?.Value;
var match = val == value; // true

How is the background task executed? I wonder if it's a threading issue and maybe the background thread for some reason has it's own cahe that hasn't gotten updated.

The background job is enqueued using Hangfire. I guess there must be some caching issue involved yeah.

It's just odd that we never had the issue prior to upgrading to umbraco 10 and vendr 3.0.3

For now the AsWritable will do as solution until I have more budget for looking into where the caching issue could be :)