The next thing we want to add is the capability to filter on dietary restrictions. This will require extensions to your Dialogflow agent for NLU but also require the implementation of new logic in Prolog for filtering the recipe database on these restrictions.

Dialogflow

As a first step, use the following CSV file to upload the dietaryRestiction entity:

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To make your Dialogflow agent extract this entity, you again need to add more training phrases, and annotate these phrases for the dietaryRestrction entity, and extend the addFilter intent with these phrases. You can use the test console of your agent to verify that it is able to recognize addFilter intents with dietary restrictions and extract the entity entries you just added.

Prolog and Patterns

In the previous capabilities that we implemented for filtering the recipe database, we often could simply use the facts that are part of that database to implement the filtering process (the applyFilter/4 rules). For example, for Capability 5: Filter Recipes by Ingredients and Cuisine we could use the ingredient/2 and cuisine/2 facts, and for Capability 6: Filter by Number of Ingredients & Recipe Steps, we could use time/2 for the cooking duration of a recipe and servings/2 for the number of servings. For computing the number of ingredients and recipe instructions steps, we had to do a bit more work, but these could also be computed quite straightforwardly from these basic facts.

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Of course, you will also need to add a base clause for this predicate with the empty list as first argument. Should this base clause succeed or fail for a dietary restriction?

Next, begin by adding some supporting predicates to the recipewe introduce one more helper predicate to check that a recipe meets a dietary restriction. The idea is to find all the ingredients of a certain recipe with identifier RecipeID and feed the resulting list in the ingredientsMeetDiet/2 predicate that we just defined to check that all these ingredients satisfy a DietaryRestriction. In the recipe_selection.pl file., add code for the body of the following rule:

diet(RecipeID, DietaryRestriction) :-

In Finally, using the diet rule/2 predicate, we need to find all the ingredients that a certain recipe has and then input them into a new function we shall create below diet, called ‘ingredientsMeetDiet’. diet should work if the list of ingredients of the inputted RecipeID fits the dietary restriction inputted DietaryRestriction. 

Make an applyFilter function for it

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Predicate to filter recipes that meet the dietary restrictions (such as ‘vegan’).

can define a rule for applying a dietary restriction filter. You are asked to define applyFilter('dietaryrestriction', Value, RecipeIDsIn, RecipeIDsOut)

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• This rule should filter recipes based on their membership to dietary restriction. To check if a recipe is a member of a dietary restriction you can use the built-in Prolog member/2 predicate.

• (member(Recipe, List of Recipes),

• diet(Recipe, Dietary Restriction))

, similar to how rules for other filters have been defined.

Extending the logic of ingredient hierarchies

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As we mentioned above, there is still information missing to implement the logic for all dietary restrictions, and also for food categories (you were already asked to add the pasta food category, but what noodles, for example?). For the dietary restrictions, you should add typeIngredient/2 facts that can facilitate the processing of filters for lactose-free (no dairy), gluten-free (no gluten),

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Here is an example of a typeIngredient ruleand spicy recipes. For all three, use a simple approach that only looks at the individual ingredients that are used in a recipe. That is, for a lactose-free recipe, no dairy products should be used; for a gluten-free recipe, no products with gluten should be used; and, for a spicy recipe, the recipe should have (at least) one ingredient that is spicy (the hasIngredient/2 predicate should come to mind here). As before, we can use one fact to deduce the other, and, deduce, for example, that if an ingredient has no gluten it must be gluten-free. We can define such relations using the same type of rule as we have seen above:

typeIngredient(Ingredient, 'gluten-free') :-
	not(typeIngredient(Ingredient, 'gluten')), !.

Here is This rule, however, still assumes that the typeIngredient(Ingredient, ‘gluten') facts are given somehow. We provide an example of the type of ingredient lists what that should look like for the 'gluten' facts:

For the lactose-free and spicy features, you should add the relevant facts. We recommend using automated approaches to compile these lists.information that you can find online and tools to automate your approach to compiling these lists.

Visuals

Nothing we ask you to do here for this capability. It’s up to you.

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