Add dietary filter to Open Food Facts search

[stuckvgn]

Summary

Adds a dietary preference filter to the Open Food Facts search. When enabled in Settings > Integration, search results are filtered to items tagged as vegan or vegetarian in the OFF database.

How it works

The OFF search API already supports filtering on ingredients_analysis_tags via its tag parameter system — the same mechanism used by the existing Search Country filter. This PR adds a tagtype parameter for ingredients_analysis when a dietary preference is set:

• Vegan → tagtype_N=ingredients_analysis&tag_contains_N=contains&tag_N=en:vegan
• Vegetarian → tagtype_N=ingredients_analysis&tag_contains_N=contains&tag_N=en:vegetarian
• No filter (default) → no change to the existing request

The tag index is set dynamically to avoid colliding with the Search Country tagtype_0 parameter when both filters are active simultaneously.

Changes

• www/activities/foodlist/js/open-food-facts.js — reads integration/dietary-filter setting and appends the tag parameter to search URLs
• www/activities/settings/views/integration.html — adds a "Dietary Filter" dropdown below the Search Country control
• www/assets/locales/locale-en.json — adds locale strings for the new control; other locales will fall back to the English key until translators add their own

[davidhealey]

Looks nice. Are there any other filters available, "Gluten Free" for example?

[stuckvgn]

Yes, Gluten Free is definitely available! The Open Food Facts API supports quite a few dietary and allergen-based filters:

Dietary/label filters (via labels_tags):

• en:gluten-free
• en:vegan
• en:vegetarian
• en:palm-oil-free
• en:organic

Allergen-free filters (via allergens_tags):

• en:gluten, en:milk, en:eggs, en:nuts, en:soy, en:fish, en:shellfish, and more

Happy to add more filters to this PR if you'd like — just let me know which ones would be most useful for Waistline users.

[stuckvgn]

Closing this PR — on reflection, this change may not be the right fit for this project. Thanks for your time!

[stuckvgn]

Sorry about the accidental close — I still have the answer to your question about additional filters. Reopening.

[davidhealey]

All those filters seems like they would be useful

[stuckvgn]

Agreed — just pushed an update to this PR that adds all of them:

• Gluten Free (via labels_tags: en:gluten-free)
• Palm Oil Free (via labels_tags: en:palm-oil-free)
• Organic (via labels_tags: en:organic)

The vegan/vegetarian filters use the ingredients_analysis tagtype; the new label-based filters use the labels tagtype — the logic picks the right one automatically based on the selection. Let me know if you'd like any others added or anything adjusted.