fix/28214 Backorders have a wrong availability on application/ld+json

[NguyenBao10]

Closes #28214.

Testing instruction:

• Create some products with different stock status, we have 3 status now (instock, outofstock, onbackorder), so 3 products is minimum
• You can set stock status for those products at Inventory tab in product admin page as below

• Visit each product's page and view page source, then find the availability attribute in LD+JSON schema
• Make sure this value is correct with product's stock status:
  onbackorder = BackOrder
  instock = InStock
  outofstock = OutOfStock

[jorgeatorres]

Hi @NguyenBao10,

Thanks for your contribution 💯! This works great, but after exploring a bit more how things are working correctly, I left a suggestion.
Even though your code is correct, the current implementation uses is_in_stock() instead of explicitly checking the stocks status via get_stock_status(), so it allows 3d party plugins to mark products as in stock regardless of the exact status.

We don't want to lose that, but we do want to handle backorders better, and I described a way to do that, but feel free to implement it other ways.

Also: +100 points on adding the changelog file with the PR, which is something a few people struggle with. I think it'd also be good to write some testing instructions as part of the PR description.

Please let me know what you think!

[jorgeatorres]

I don't think we should allow an empty $stock_status_schema as that might result in broken JSON. Also, looking at how this is working right now, I can see that we are really using the result from is_in_stock() which involves a filter.

We don't want to lose that flexibility (for other plugins to use that filter to change the "in stock" status) nor affect backwards compatibility, so I'd suggest we do things slightly different.

How about instead of a case we do a check for is_in_stock() and set $stock_status_schema to either InStock or BackOrder if the stock status is explicitly "backorder". Otherwise, we set $stock_status_schema to OutOfStock.

That way we preserve current behavior and also reduce the chances that we end up with an empty $stock_status_schema.

For example, something along these lines might work:

if ( $product->is_in_stock() ) {
	$stock_status_schema = ( 'onbackorder' === $product->get_stock_status() ) ? 'BackOrder' : 'InStock';
} else {
	$stock_status_schema = 'OutOfStock';
}

What are your thoughts?

[NguyenBao10]

yeah, i did not notice about 3d party plugins, so your way is more flexible and better, let me improve this, thank you

[codecov]

Codecov Report

Merging #37837 (c5285ec) into trunk (dfb23ea) will decrease coverage by 0.0%.
The diff coverage is 0.0%.

❗ Current head c5285ec differs from pull request most recent head 4dd38a4. Consider uploading reports for the commit 4dd38a4 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             trunk   #37837     +/-   ##
==========================================
- Coverage     51.5%    51.5%   -0.0%     
- Complexity   17280    17283      +3     
==========================================
  Files          430      430             
  Lines        80026    80037     +11     
==========================================
+ Hits         41215    41216      +1     
- Misses       38811    38821     +10     

Impacted Files	Coverage Δ
...ocommerce/includes/admin/class-wc-admin-assets.php	0.0% <ø> (ø)
...eta-boxes/class-wc-meta-box-product-categories.php	0.0% <0.0%> (ø)
plugins/woocommerce/includes/class-wc-ajax.php	4.3% <0.0%> (ø)
.../woocommerce/includes/class-wc-structured-data.php	0.0% <0.0%> (ø)

... and 1 file with indirect coverage changes

[jorgeatorres]

LGTM. Thank you @NguyenBao10 for your contribution!