(fix): Determine denormalized product inventory status during Shopify import

[spencern]

Fixes an unreported issue where denormalized product inventory status was not set during import of products from Shopify.

This PR resolves this by setting isSoldOut, isLowQuantity, and isBackorder flags correctly on the top level product during import.

[impactmass]

Looks good generally, but I have some questions:

• Looks like there's no equivalent isLowQuantity value from the Shopify data?
• How does this change affect anyone that already used the current version to import products?

And for testing:

• I just imported products and checked that the new values are set on the top level product.

[impactmass]

@spencern looks like you missed the comment above

[spencern]

@impactmass
arg. I thought I responded to this already, but probably have a draft mode somewhere.

isLowQuantity does not have an equivalent on Shopify, so we just set it to false.

Re: this change affecting anyone that already used the current version to import products, that's a great question. I'm pretty sure that top-level field gets updated every time inventory gets changed, but it might be worth including a migration here that loops through all products and updates them anyway? I could write the migration to check for a shopifyId first and then to check for the presence of one of these fields isLowQuantity etc that would be absent otherwise so that it only happens on Shopify products that have not been updated

[impactmass]

I think if we can confirm that the top-level field gets updated every time inventory gets changed, this should be good to approve then.

[spencern]

@impactmass Those do get updated as part of this denormalize function that gets called when variants are updated. See catalog.js https://github.com/reactioncommerce/reaction/blob/master/server/methods/catalog.js#L188

It's then called on L564 by updateVariant, and on L965 by updateProductField.

[spencern]

I've added one more update in here to fix the way variant images are imported. To this point only the first image imported was added to the grid via toGrid: 1 but after experimenting with how Reaction assigns product media to the grid when creating a product and variants, I've updated the Shopify importer to now add the first image for each variant to the grid as well. This should resolve the situation we've seen in #3368 where grid item layouts do not show additional product media that has been imported from Shopify.

It will not affect existing images from Shopify that have been imported.

I'm not certain if we want to add a migration here, as it's possible that people have built their apps to account for the way that the media was imported originally, but a migration could be added to set the first image of each variant to have toGrid: 1

I lean towards this being a fix and not adding a migration, but could understand an argument either way. @impactmass what do you think?

[spencern]

@impactmass ready for another review here.

[impactmass]

Yes, doing a migration in this case can cause a break in the way someone else already built on earlier imports. So, I tend towards the way it's setup here.