Changes

== Summary ==

== Summary ==

* <code>nutrition_data_per</code>: <code>100g</code> or <code>serving</code>

* <code>nutrition_data_per</code>: <code>100g</code> or <code>serving</code>

* <code>serving_size</code>: (optional, but very useful, in particular if the nutrition facts are specified per serving)

* <code>serving_size</code>: (optional, but very useful, in particular if the nutrition facts are specified per serving)

* for each nutrient:

* For each nutrient:

** <code>{nutrient-id}</code> (e.g. <code>saturated-fat</code>, <code>energy-kcal</code>): value for the nutrient, for the size specified in the field  <code>nutrition_data_per</code>. This is a string made of the modifier ("<", ">" or "") and the value without unit ("17.8", "34,7", "< 0.1", etc).

** <code>{nutrient-id}</code> (e.g. <code>saturated-fat</code>, <code>energy-kcal</code>): value for the nutrient, for the size specified in the field  <code>nutrition_data_per</code>. This is a string made of the modifier ("<", ">" or "") and the value without unit ("17.8", "34,7", "< 0.1", etc).

** <code>{nutrient-id}_unit</code> (e.g. saturated-fat_unit, energy-kcal_unit): the unit of the value passed (e.g. "g", "mg", "kcal", "kJ", "%", "")

** <code>{nutrient-id}_unit</code> (e.g. saturated-fat_unit, energy-kcal_unit): the unit of the value passed (e.g. "g", "mg", "kcal", "kJ", "%", "")

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 simple conversion ratio between kcal and kJ

* 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

** 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)

* Old apps used to pass energy (as we had only one energy field instead of energy-kcal + energy-kj)

** for those apps, the energy_unit field is used to populate the corresponding energy-kj or energy-kcal field

** 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) ====

* nutrient-id_value : what was entered and passed in the nutrient-id field

* <code>{nutrient-id}_value</code>: what was entered and passed in the nutrient-id field.

* nutrient-id_unit : what was entered and passed in the nutrient-id_unit field

* <code>{nutrient-id}_unit</code>: what was entered and passed in the nutrient-id_unit field.

* nutrient-id : the value converted in the default unit (currently kJ for all energy fields (including energy-kcal), otherwise gram)

* <code>{nutrient-id}</code>: the value converted in the default unit (currently kJ for all energy fields (including energy-kcal), otherwise gram).

* nutrient-id_[value of nutrition_data_per) is set to nutrient-id (e.g. if nutrition_data_per is "100g", the value of sugars_100g is set to the value of sugars

* <code>{nutrient-id}_(100g|serving)</code>: is set to <code>{nutrient-id}</code> (e.g. if <code>nutrition_data_per = 100g</code>, the value of <code>sugars_100g</code> is set to the value of sugars.

* if the serving size is known, we compute the value for the other field (nutrient-id_100g or nutrient-id_serving) in default unit

* If the serving size is known, we compute the value for the other field (nutrient-id_100g or nutrient-id_serving) in default unit.

=== Data display ===

=== Data display ===

The OFF web site, and apps, should only use these OFF proocessed fields to display the nutrition data:

The OFF web site, and apps, '''should only use these OFF processed fields''' to display the nutrition data:

* nutrient-id_100g or nutrient-id_serving (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 the value of <code>nutrition_data_per</code>): value in g or in kJ. The values are passed as float/double???

* nutrient-id_value : to show the original entered/passed data (useful for characters as "<" or "~"}.

* <code>{nutrient-id}_modifier</code> to get the value modifier ("<", ">", "~")

* <code>{nutrient-id}_value</code>: to show the original entered/passed data.

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 in g or in kJ to the desired unit.

* Convert the value from g or kJ to the desired unit.

Notes:

Notes:

* Don't use the nutrient-id_value and nutrient-id_unit 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

(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 thing (a bit) simpler ==

== 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 <code>{nutrient-id}</code> fields (such as <code>energy-kj</code>, <code>saturated-fat</code>) to <code>{nutrient-id}_value</code>, so that it matches the name of the field stored. It also makes clearer where the value is coded.

* Store the energy-kcal values in kcal, without converting them to kJ

* Store the <code>energy-kcal</code> values in kcal, without converting them to kJ

** This is probably what people intuitively expect

** This is probably what people intuitively expect

** It removes unnecessary conversions from kcal to kJ and back (which is not trivial, as some people/apps may choose a different conversion factor, such as 4.2 or 4.185)

** It removes unnecessary conversions from kcal to kJ and back (which is not trivial, as some people/apps may choose a different conversion factor, such as 4.2 or 4.185)

** 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 thing (a bit) more complex ==

== 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.

e.g. saturated-fat_prepared_100g, saturated-fat_prepared_value etc.

e.g. saturated-fat_prepared_100g, saturated-fat_prepared_value etc.