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How to populate a Rails dropdown menu with a json array


(Jameson Trinker) #1

I have an Ant show page that displays detailed information about various types of ants. On that page there are two drop downs, one for environment: [indoor, outdoor], and one for diet: [sugar, fat, protein].

When you select a param from each it renders out a product page depending on the params. However, some combinations result in nil, like a carpenter ant doesn’t have a product associated with indoor, sugar.

I’m trying to get the dropdowns to populate based on whether or not a combination is nil. If someone selects indoor I’d like sugar to not appear in the next drop down if that combo doesn’t exist.

So far I have I have two methods creating json arrays for only the available items:

def food_sources
  food_sources = Ant.find(params[:ant_id]).product_recommendations.where(environment: params[:environment]).map(&:diet)
  render json: food_sources.to_json
end

def environments
  environments = Ant.find(params[:ant_id]).product_recommendations.where(diet: params[:diet]).map(&:environment)
  render json: environments.to_json
end

For example, if I input

http://localhost:3000/ants/27/food_sources?environment=indoor

into the browser it returns

["sugar","protein"]

bc for the ant with an id of 27 only has two options for outdoor indoor diets, instead of the possible three.

My question is how do I pass this array into my rails dropdown if someone picked the above combination? Right now my drop down looks a little like this:

= select_tag :environment, options_for_select([["Select One"], "Indoor", "Outdoor"])