find_by.rb

Thing = Struct.new(:name)

things = [
  Thing.new("PlayStation"),
  Thing.new("Xbox")
] # => [#<struct Thing name="PlayStation">, #<struct Thing name="Xbox">]

things.find { |thing| thing.name == "PlayStation" } # => #<struct Thing name="PlayStation">

people = [
  { name: "Justin" },
  { 'name' => "Dave" }
]

people.find { |person| person[:name] == "Justin" } # => {:name=>"Justin"}
people.find { |person| person['name'] == "Dave" } # => {"name"=>"Dave"}

module Enumerable
  def find_by(field, value)
    find { |item|
      if item.respond_to?(:key?) && item.key?(field)
        item[field] == value
      elsif item.respond_to?(field)
        item.public_send(field) == value
      else
        false
      end
    }
  end
end

things.find_by(:name, "PlayStation") # => #<struct Thing name="PlayStation">
people.find_by(:name, "Justin") # => {:name=>"Justin"}
people.find_by('name', "Dave") # => {"name"=>"Dave"}