CODEWITHSUNDEEP
rubyruby-on-rails-3activerecordrails-activerecord
Hrishikesh Sardar
Hrishikesh Sardar

Reputation: 2917

Find intersection of two array of hashes depending upon hash contents

I get this two array of hashes after performing join

array 1

[#<State id: 1, name: "Alabama">, #<State id: 1, name: "Alabama">, #<State id: 1, name: "Alabama">, #<State id: 1, name: "Alabama">, #<State id: 2, name: "Alaska">, #<State id: 2, name: "Alaska">, #<State id: 4, name: "Arkansas">, #<State id: 4, name: "Arkansas">, #<State id: 4, name: "Arkansas">, #<State id: 6, name: "Colorado">, #<State id: 6, name: "Colorado">, #<State id: 6, name: "Colorado">, #<State id: 11, name: "Georgia">, #<State id: 14, name: "Illinois">, #<State id: 18, name: "Kentucky">, #<State id: 18, name: "Kentucky">, #<State id: 22, name: "Massachusetts">, #<State id: 48, name: "Washington">]

array 2

[#<City id: 1, name: "Abbeville", state_id: 1>, #<City id: 1, name: "Abbeville", state_id: 1>, #<City id: 1, name: "Abbeville", state_id: 1>, #<City id: 4543, name: "Abingdon", state_id: 14>, #<City id: 8282, name: "Accord", state_id: 22>, #<City id: 3808, name: "Acworth", state_id: 11>, #<City id: 6855, name: "Adairville", state_id: 18>, #<City id: 6855, name: "Adairville", state_id: 18>, #<City id: 18895, name: "Adams County", state_id: 6>, #<City id: 4, name: "Addison", state_id: 1>, #<City id: 4, name: "Addison", state_id: 1>, #<City id: 17510, name: "Addy", state_id: 48>, #<City id: 1054, name: "Adona", state_id: 4>, #<City id: 1054, name: "Adona", state_id: 4>, #<City id: 577, name: "Akiachak", state_id: 2>, #<City id: 1056, name: "Alicia", state_id: 4>, #<City id: 583, name: "Ambler", state_id: 2>, #<City id: 2783, name: "Aspen", state_id: 6>]

I want to make a third array from the above two based on the value of state_id in each array

in this case for example [#, .... and so on

for your help the first two hashes array i got using join query

@states = State.joins("INNER JOIN property_of_interests ON property_of_interests.state_id = states.id").where(:property_of_interests => {:user_id => current_user.id})
@cities = City.joins("INNER JOIN property_of_interests ON property_of_interests.city_id = cities.id").where(:property_of_interests => {:user_id => current_user.id})

can I work on the query itself to get the desired output ?.

I tried something like 

`@states.select("@states.name,@cities.name").joins("INNER JOIN @cities ON @cities.state_id = @states.id")`

but it doesnt work.

More Information

states id, name

cities id, name, state_id

property_of_interests id, user_id, state_id, state_name

Desired output like

State Name City Name
Alabama    Abbeville
Alabama    Abbeville
Alabama    Abbeville
....

Upvotes: 0

Views: 83

Answers (1)

Satya
Satya

Reputation: 4478

You would do something like:

City.all.each do |city|
  puts "#{city.state.name} #{city.name}"
end

Alternately, as an array:

arr = City.all.map { |c| [c.state.name, c.name] }

Or as an array of hashes:

arr = City.all.map { |c| {state: c.state.name, city: c.name} }

Or to actually answer the question, since you want to start with the properties_of_interest table:

PropertyOfInterest.all.each do |prop|
  prop.state.cities.each do |city|
    puts prop.state.name, city.name
  end
end

Upvotes: 1

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