class Jbuilder

end
json.content comment.formatted_content
json.comments(@post.comments) do |comment|

More commonly, you'd use the combined iterator, though:

{ "comments": [ { "content": "hello" }, { "content": "world" } ]}

end
json.child! { json.content "world" }
json.child! { json.content "hello" }
json.comments do

Example:

Turns the current element into an array and yields a builder to add a hash.

def child!
  @attributes = [] unless ::Array === @attributes
  @attributes << _scope{ yield self }
end