We need to sort out the refresh scenario.

[monsieurtanuki]

          We need to sort out the refresh scenario. 

1. There's been the language change issue for a while (mostly happens to me when I demo the app) The app should offer to reload all products on language change #1651
2. I'm not clear if we refresh systematically on opening the full product page (I believe we should, especially as the structure of the knowledge panel evolves)
3. That is going to be all the more pressing that we're going to have the new Nutri-Score soon (March/April?).
   https://www.francetvinfo.fr/replay-radio/le-billet-vert/alimentation-les-regles-du-nutri-score-evoluent_6246153.html

• Nutri-Score: We'll need a team brainstorm to find how we want to showcase the change in the app.
  • Do nothing
  • Refresh (silently or not) all products from all installs in a way that is compatible with the server not being overwhelmed ?
  • Refresh (silently or not) on opening the product ?
  • Refresh manually with a promotion like: "The new Nutri-Score formula is here. Tap to refresh the score for all products you have ever scanned."

Originally posted by @teolemon in #4940 (comment)

[monsieurtanuki]

@teolemon They are indeed related to #4940, but all those questions deserve at least one specific issue.

[monsieurtanuki]

@teolemon Definitely related to #4717, where my review said that if we want to do it in bulk, we need background tasks.

What you've added in your comment is:

• could be overwhelming for the server too (bulk scenario)
• other cases to refresh the product (not only when the user changes the app language) - e.g. when opening the product page

All local products should be refreshed.
Possible pitfalls:

1. bulk refresh could crash the server.
   Possible solution: slow bulk refresh (e.g. 100 products download, then we wait 10 minutes before the next 100 product download)
2. some products are more interesting, but the bulk refresh (especially if slow) may treat them at the end.
   Possible solution: in parallel, a specific refresh for all the products in (recent) history, ordered by descending last access time

Specific products should definitely be refreshed first. When we look at a product list, we already see the individual nutriscores. Should we refresh the product instantly, even if the product page is not open? How often?

Other points to consider:

• some users may have limited connectivity or connectivity with a price proportional to the data load. The more we (silently) load, the more they have to pay
  Possible solution: make the auto-download mode optional.
• should the user know what's going on, e.g. if all the nutriscores are refreshed / if this specific nutriscore is refreshed?
  Possible solution: at least we should provide a visible timestamp.

[teolemon]

• Add a system to refresh all cached products for Nutri-Score v2 #4545