Question

I need to fetch all current_user.friends statuses and then sort them by created_at.

class User < ActiveRecord::Base
 has_many :statuses
end

class Status < ActiveRecord::Base
 belongs_to :user
end

And in the controller:

def index
    @statuses = []
    current_user.friends.map{ |friend| friend.statuses.each { |status| @statuses << status } }
    current_user.statuses.each { |status| @statuses << status }

    @statuses.sort! { |a,b| b.created_at <=> a.created_at }
end

current_user.friends returns an array of objects User

friend.statuses returns an array of objects Status

Error:

comparison of Status with Status failed
app/controllers/welcome_controller.rb:10:in `sort!'
app/controllers/welcome_controller.rb:10:in `index'

Answer 1

I had a similar problem, solved with the to_i method, but can’t explain why that happens.

@statuses.sort! { |a,b| b.created_at.to_i <=> a.created_at.to_i }

By the way, this sorts in the descending order. If you want ascending order is:

@statuses.sort! { |a,b| a.created_at.to_i <=> b.created_at.to_i }