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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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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 about 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), and 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:
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Even though some of the recipe features that we have looked at require careful analysis, those that require more work than simply inspecting basic facts in the recipe database were all based on reasoning about individual ingredients. That is, we verified whether an ingredient is of a particular type, either a type of food or a type of dietary restriction. If you like a challenge, you can also consider other recipe features that consider more global features of a recipe, such as a recipe being low-carb or cheap. How would you define the logic for such filters? What kind of information would you need to add to the database to be able to define features like these?
Visuals
You can update the visuals based on what you think will help the user the most. Think about how you can support the implemented capability visually.
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