Show the Nutri-Score provided by producers when it is available

[stephanegigandet]

Some producers send us data for their products including the Nutri-Score grade (and sometimes the underlying Nutri-Score score as well), in particular through GS1.

Currently we do not display this score, but instead display the score that we compute from nutrition facts.

The issue is that sometimes we have a wrong computed Nutri-Score, for a variety of reasons:

• the product nutrition facts have changed and our data is stale
• fibers are not specified
• fruits and vegetables are estimated from the ingredients list, which is imprecise
• some products need to have their Nutri-Score computed on the nutrition facts for the prepared product, but we don't always trigger this behaviour if we don't have a precise enough category

It is now very rare that producers send a wrong Nutri-Score, so we would like to display the producer supplied Nutri-Score in the product attributes and knowledge panels that we show on the website and in the app. In the details, it would still be possibly to mention the source (producer or computed) and highlight any discrepancy that might exist (just as we have warnings to explain the fruits/vegetables are estimated, or the fibers unknown).

This will also motivate more producers to send us data directly, including Nutri-Score data.

[CharlesNepote]

It's not easy to comment, as it's hard to understand the underlying rules and see all the implications.

I think we should firstly build a schema with all the different cases. I have started this one but I have missed some cases and some actions (eg. what is exported in the CSV file?). It can be a base to talk. @stephanegigandet don't hesitate to copy/paste the code or modify my comment. (You can modify the schema with https://mermaid.live .)

flowchart TD
    A[NS from producer \n NSFP] -->|sent thru pro platform| B[nutriscore_grade_from_producer field]
    I[NS computed by OFF \n NSC] --> J[nutriscore_grade field]
    G[NS label from producer or user \n NSL] --> H[label field]
    P[NS detected by Robotoff \n -- from last picture? \n NSR]
    O[NS displayed on last version of the product, \n perhaps seen by the user]
    K[NS displayed on our last product's photo \n NSPF] --> C
    B --> C{analyze}
    H --> C
    J --> C
    C -->|NSFP <> NSC \n and NSFP is newer than NSC| D[nutriscore_grade_from_producer is diplayed with a warning:\nNS from producer is different from the one we compute due to lack of data from the producer]
    C -->|NSFP <> NSC and NSFP > 1 year \n and NSC is newer than NSFP| E[display NSC]
    C -->|NSL <> NSFP| F[trigger data-quality-error to let \n data quality team override producer's data]
    C -->|NSPF is at least one year older than NSFP| M[trigger data-quality-warning for the producer \n and for the users]
    M --> N[Ask mobile user to take another photo]

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