Rails 7 adds Enumerable#maximum

Rails 7 adds support for Enumerable#maximum and Enumerable#minimum to easily calculate the maximum and minimum value from a collection of enumerable elements.

Before Rails 7, we could only achieve the same results with a combination of map & max or min functions over the enumerable collection.

=> Item = Struct.new(:price)
=> items = [Item.new(12), Item.new(8), Item.new(24)]

=> items.map { |x| x.price }.max
=> 24

=> items.map { |x| x.price }.min
=> 8

This is simplified with Rails 7's newly-introduced maximum and minimum methods.

=> items.maximum(:price)
=> 24

=> items.minimum(:price)
=> 8

These methods are available through Action Controller's fresh_when and stale? for convenience.

# Before Rails 7

def index
  @items = Item.limit(20).to_a
  fresh_when @items, last_modified: @items.pluck(:updated_at).max
end

# After Rails 7

def index
  @items = Item.limit(20).to_a
  fresh_when(@items)
end

The etag or last_modified header values will be properly set here based on the maximum value of the updated_at field.

Check out this pull request for more details.