Constructing queries by merging scopes.

howiuseit.rb

@post = Post.hero.group_by_category("include_with_hero", ["General"])
#Intended result is all posts that fall under the category General AND Hero

#I want this to work with multiple categories, so something like
@post = Post.hero.group_by_category("include_with_hero", ["General", "Foo", "Bar"])

#should return all posts that fall under General AND Foo AND Bar AND Hero categories

post.rb

    #scope that isolates "heroes" and "projects"
    scope :hero, -> {Post.includes(:categories).where('categories.title = (?)', "Hero")}
    scope :projects, -> {Post.includes(:categories).where('categories.title = (?)', "Projects")}
    
     #filter posts by category
    def self.group_by_category(action,category)
        case action
        when "include"
         post = Post.includes(:categories).where('categories.title IN (?)', category).order(created_at: :desc).references(:categories)

        when "exclude"
         post = Post.includes(:categories).where('categories.title NOT IN (?)', category).references(:categories)

        when "include_with_hero"
         temp = Post.includes(:categories).where('categories.title IN (?)', category).hero
        else
         post = Post.all
        end
    end

solution.rb

@projects = Post.is_draft("no").projects & Post.hero

@posts = Post.is_draft("no").group_by_category("include", ["General", "Technical"]) & Post.hero
#This will give me all posts that are not drafts, that belong to General OR Technical AND Hero.

So the intended result can be achieved by merging scopes, mentioned above.
dang