Emptying cart causing an error on donate page

Trying to solve this problem results in an "access denied" message on the /donate page. I suspect this is because Commerce Donation Flow is using the same order ID for subsequent donations but there has already been a donation made, even if it has been removed from the cart.

Creating a new order seems to get around the problem, but there's an error getting the form state values in DonationLevelWidget->massageFormValues().

Yes, we have other workflows and order items. This would happen even with just the donation workflow but is more obvious with other products.

OK creating a new order is definitely not the right way to do it. What happens after I make a donation but don't complete the workflow, then create another donation, is that I end up with 2 carts. The original order should be updated or handled another way.

So there are 2 related issues which could be fixed here:

1. Handle removing donations from the cart
2. Handle visiting /donate when there is already a donation in the cart

For 2, I suggest simply disabling the form at /donate with a message stating the previous donation needs to be removed from the order first.

This addresses point 1 only. If you remove the donation from the card the visit /donate again, then a new donation item will be added.

• This takes into account the new method in dev: #3178281: Create helper method to addDonationItem
• It removes checking if there are any items from the access check method
• It recalculates totals a couple of extra times as Commerce's step checking process requires a total price

With point 2, visiting /donate when there is already a donation in the cart creates adds another donation to the cart. This may not be desirable.

With point 2, visiting /donate when there is already a donation in the cart creates adds another donation to the cart. This may not be desirable.

Actually that's not quite accurate. It only adds another donation if the current donation is the placeholder $0 donation. Once a donation has been selected it replaces the existing one which has a price.

In short, visiting /donate multiple times generates multiple $0 donations in the cart.

Fixes point 2 above and a resulting error regarding the currency code not being available.

Note: this is separate to this issue: #3211899: Use an enabled currency as the default currency

Merge requests can get a little confusing when there are multiple changes. All the changes are here: https://git.drupalcode.org/project/commerce_donation_flow/-/merge_reques...