[JrAdhoc]

Migration of website_sale_product_multi_website to 20.0.

Why it is not a straight port

Odoo 20 removed can_access_from_current_website() — the hook this module overrode to restrict a product to several websites. There is no definition and no caller left in the whole core. The check moved inline into ir.http._pre_dispatch():

website_id = request.env.context.get('website_id') or request.env.context.get('host_id')
for record in args.values():
    if isinstance(record, models.BaseModel) and 'website_id' in record._fields:
        if record.website_id and record.website_id.id != website_id:
            raise werkzeug.exceptions.NotFound()

The product page takes the product.template as a typed route argument, so this runs on every product URL. With website_id computed as website_ids[:1], a product published on two websites would answer 404 on all of them but the first.

What this does instead

website_id now answers the website being browsed: computed per context, it returns the current website whenever the product is assigned to it, and the first one of website_ids otherwise. A search method resolves website_id searches through website_ids.

That is exactly what the core needs to match a product against a website, so three overrides are no longer necessary and are dropped:

• website.website_domain() and sale_product_domain() — the search method already resolves them. The multi_website_domain context and its Domain.custom() go with them, which also sidesteps Domain.custom(to_sql=...) changing signature in 20.0 ((model, alias, query) → (table)).
• website.snippet.filter — it only existed to turn that context on.
• _compute_website_published() and _search_website_published() — the core computes both correctly from website_id on its own.

The compute reads website_ids with sudo(): it is not readable by the public user, and the core still evaluates the website domain in memory through filtered_domain() on accessory and alternative products.

Views

The product.product list view inherit is dropped: website_sale no longer shows website_id in product_product_website_tree_view in 20.0, so the xpath had no anchor left and there is no core column to mirror. The form and the product.template list view inherits are unchanged, and both anchors were checked against 20.0.

Tests

test_01 and test_02 no longer call the removed method; they assert the HTTP status of the product page per website instead, which is what _pre_dispatch now controls. Four tests are added: website_id answering the browsed website, searching by website_id through website_ids (both for the in operator the core uses and for a text operator a custom filter builds), and a website in use refusing to be deleted.

Deleting a website

website_ids becomes ondelete="restrict". Dropping the stored website_id drops its foreign key along with it, and a many2many cascades by default: deleting a website would have emptied website_ids silently, and an empty website_ids means "every website" — so a product exclusive to the deleted website would have ended up published on all the remaining ones. A test covers it.

Notes for reviewers

• website_id becomes non-stored on a field the core declares stored, so the product_template.website_id column stays behind on databases that already had the module. Nothing writes to it any more and Odoo only logs it as a removed column; I left it rather than adding a migration script that nulls out data.
• The .pot (and i18n/it.po) still carry entries for model_website and model_website_snippet_filter, which this module no longer inherits. I left them for the bot to regenerate after the merge rather than hand-editing a generated file — say the word if you prefer them cleaned up here.
• The test suite was not run locally (no database at hand); it is on CI.