Checking if the variant belongs to current product

[Akarshit]

Fix for #3227

Problem

The variantId was not getting updated when selecting a new product.

Solution

In the check for updating the product/variant instead of only checking if variantId == null also check that variantId belong to the selected product

Another solution

Maybe a better solution is to call ReactionProduct.setCurrentVariant(null) as soon as some PDP page is opened.

To test

1. Run reaction
2. Add image to example-product and publish.
3. Add another product with image(say test-product).
4. Go to home and then select example-product(image should show).
5. Go to home and select test-product(image should show).
6. Do a refresh(image should show).

[brent-hoover]

I think this is a workaround, as we shouldn't be getting a selectedVariant that's not associated with the product, but this fixes several pretty serious bug and fixing the source of the issue may involve rewriting some core PDP stuff.

[brent-hoover]

Tested. Verified fixed.

[janus-reith]

Could you test again?
This is broken for me, but could also be related to my pdp variant modifications.
Accesing the main page works, but if I try to directly browse to a variant by handle, like
http://localhost:3000/product/handle/id, the pdp just shows the loading spinner and console throws:

meteor.js?hash=cbcc712d51de4298c275e8dcf25c66c29914f19a:992 TypeError: Cannot read property 'indexOf' of undefined
    at _variantIsSelected (products.js:84)
    at ReactiveDict.ReactionProduct.setProduct (products.js:169)
    at composer (productDetail.js:652)
    at tracker.js:37
    at Tracker.Computation._compute (tracker.js?hash=997515fa2d5b0530ba07741da556c4b36963ef3b:339)
    at Tracker.Computation._recompute (tracker.js?hash=997515fa2d5b0530ba07741da556c4b36963ef3b:358)
    at Object.Tracker._runFlush (tracker.js?hash=997515fa2d5b0530ba07741da556c4b36963ef3b:532)
    at onGlobalMessage (meteor.js?hash=cbcc712d51de4298c275e8dcf25c66c29914f19a:448)

[brent-hoover]

@janus-reith I believe we dropped support for browsing to particular variant by URL a while ago. Is that what you mean?

Since this is already released, if you have a problem can you open a new issue?