Get distinct elements from a Rails ActiveRecord query

问题

I've got a query in Rails like this:

@addresses=People.select("first_name, state").where("first_name = 'Bob'")

Is there a way I can iterate over addresses and pull out the distinct states, so that I know in which states someone named bob lives?

I'm trying to avoid:

@states = []
@address.each.do |add|
  if !@states.contains?(add.state)
    @states.push add

That just seems like bad form.

回答1:

@states = People.where(first_name: 'Bob').uniq.pluck(:state)

来源：https://stackoverflow.com/questions/10130818/get-distinct-elements-from-a-rails-activerecord-query