如何创建临时属性并在Rails活动记录中的json响应中使用它

Question

I am new to ROR. I am having a controller where i am getting the search results in available_users variable..

availble_users  //some active record result with id,name & address
available_users.each do |userstatus|
          userstatus.class_eval do
          attr_accessor :is_friend
          end
          if current_user.invitations.find_by(:friend_id => userstatus.id) //invitation is another table 
            userstatus.is_friend = "true"
          else
            userstatus.is_friend = "false"
          end
        end
         render json: available_users

but when i am getting the response on ajax request it is serving the same array without including is_friend column.

here is my json response.

id: 2
name: abc
address:

please can anyone figure me out why it is not appending this temporary attribute. Thanks.

Answer 1

what you have will work if you pass the methods option to_json

    render json: available_users.to_json(:methods => :is_friend)

Or you could do this

    available_users.each do |userstatus|
      if current_user.invitations.find_by(:friend_id => userstatus.id) //invitation is another table 
        userstatus["is_friend"] = "true"
      else
        userstatus["is_friend"] = "false"
      end

    end
    render json: available_users

[]= is an alias for write_attribute