Rails: Query an array based on a record (string) from another array

Question

Each User has many SaleItems and many NeededItems. I want to query User 1's SaleItem names to see if any of them has a similar name to User 2's NeededItems ("name" is the only attribute)

@needed_item_of_user2 = NeededItem.where("user_id = ?", 2).first  
# "Pikachu Pokemon card"
@sale_items_of_user1 = SaleItem.where("user_id = ?", 1) 
# "Baseball cards", "Water Heater", "Pikachu doll", "Squirtle Pokemon card"
@matching_sale_items = @sale_items_of_user1.some_method_querying_the_names.@needed_item_of_user2.name 
# It should output either "Squirtle Pokemon card" (high accuracy) or 
# all except "Water Heater" (low accuracy)

What method should I use to get an accurate match for @matching_sale_items?

I've tried:

@matching_sale_items = @sale_items_of_user1.select do |sale| 
  sale["name"] == @needed_item_of_user2.name
end

based on How do I search within an array of hashes by hash values in ruby?

and

@matching_sale_items = @sale_items_of_user1.map do |a|
  a.name.downcase
end.grep(/#{@needed_item_of_user2.name.downcase[0,4]}/)  
# outputs strings

In the future, I want to use that method to query the SaleItems Table for matches with the NeedItems Table.

kolas · Accepted Answer · 2017-10-16 07:49:05Z

1

You can try to do this:

user1 = User.find 1
user2 = User.find 2
needed_items_names = user2.needed_items.pluck(:name)
matched_items = user1.sale_items.where(name: needed_items_names)

Docs to read:

http://guides.rubyonrails.org/active_record_querying.html#pluck
http://guides.rubyonrails.org/active_record_querying.html#hash-conditions 2.3.3 Subset Conditions

answered Oct 16, 2017 at 7:49

kolas

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1 Comment

Jun Dalisay Over a year ago

Thanks for pluck. I found this one to search the array for nonexact matches stackoverflow.com/questions/2220423/… @matched_items = user1.sale_items.where("LOWER(name) ILIKE ?", "%#{@needed_item_of_user2.name.downcase[0,5]}%")

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