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Nutrients handling in Open Food Facts: Difference between revisions
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Notes about the energy fields: | Notes about the energy fields: | ||
* Energy on labels can be written in kcal, kJ or both | * Energy on labels can be written in kcal, kJ or both | ||
* | * When the energy is written in both, there is no universally defined conversion ratio between kcal and kJ. | ||
** This is because labelling laws in EU, US, CA etc. specify that the energy fields can (or must) be computed by multiplying and summing values for carbohydrates, proteins, fat etc. | ** This is because labelling laws in EU, US, CA etc. specify that the energy fields can (or must) be computed by multiplying and summing values for carbohydrates, proteins, fat etc. | ||
** That's why we now store 2 energy fields, and not just one | ** That's why we now store 2 energy fields, and not just one | ||
** | ** See https://esha.com/calorie-calculation-country/ for details | ||
* energy-kj and energy-kcal are the identifiers (nutrient-id) of the "Energy in kJ" and "Energy in kcal" fields. | * <code>energy-kj</code> and <code>energy-kcal</code> are the identifiers (<code>{nutrient-id}</code>) of the "Energy in kJ" and "Energy in kcal" fields. | ||
* | * Old apps used to pass energy (as we had only one energy field instead of energy-kcal + energy-kj) | ||
** | ** For those apps, the <code>energy_unit</code> field is used to populate the corresponding <code>energy-kj</code> or <code>energy-kcal</code> field | ||
==== Fields entered and computed by the OFF backend (Product Opener) ==== | ==== Fields entered and computed by the OFF backend (Product Opener) ==== | ||
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=== Data display === | === Data display === | ||
The OFF web site, and apps, should only use these OFF processed fields to display the nutrition data: | The OFF web site, and apps, '''should only use these OFF processed fields''' to display the nutrition data: | ||
* <code>{nutrient-id}_100g</code> or <code>{nutrient-id}_serving</code> (depending on the value of nutrition_data_per): value in g or in kJ. The values are passed as float/double??? | * <code>{nutrient-id}_100g</code> or <code>{nutrient-id}_serving</code> (depending on the value of nutrition_data_per): value in g or in kJ. The values are passed as float/double??? | ||
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The web site and apps '''must''': | The web site and apps '''must''': | ||
* Indicate if the nutrition facts are per 100g or per serving. | * Indicate if the nutrition facts are per 100g or per serving. | ||
* Convert the value | * Convert the value from g or kJ to the desired unit. | ||
Notes: | Notes: | ||
* Don't use the <code>{nutrient-id}_value</code> and <code>{nutrient-id}_unit</code> fields | * Don't use the <code>{nutrient-id}_value</code> and <code>{nutrient-id}_unit</code> fields | ||
** The nutrient-id may be empty as some apps don't pass a unit, and we use a default unit for the field | ** The <code>{nutrient-id}</code> may be empty as some apps don't pass a unit, and we use a default unit for the field | ||
** The value may be per 100g or per serving | ** The value may be per 100g or per serving | ||
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(What does this mean? only allow editing of the off processed field)??? | (What does this mean? only allow editing of the off processed field)??? | ||
== Possible improvements to make | == Possible improvements to make things (a bit) simpler == | ||
* In the API, rename the "nutrient-id" fields (such as energy-kj, saturated-fat) to "nutrient-id_value", so that it matches the name of the field stored. It also makes clearer where the value is coded. | * In the API, rename the "nutrient-id" fields (such as energy-kj, saturated-fat) to "nutrient-id_value", so that it matches the name of the field stored. It also makes clearer where the value is coded. | ||
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** This would be a breaking change if some apps use the energy-kcal_100g/serving or energy-kj_100g/serving fields | ** This would be a breaking change if some apps use the energy-kcal_100g/serving or energy-kj_100g/serving fields | ||
== Possible improvements to make | == Possible improvements to make things (a bit) more complex == | ||
The current API does not allow to store values for the prepared product, but it can be done on the OFF web site. | The current API does not allow to store values for the prepared product, but it can be done on the OFF web site. | ||