CODEWITHSUNDEEP
ruby-on-railsrubyruby-on-rails-3
Tyler
Tyler

Reputation: 33

There is error in sorting code which does not involve any callbacks

In my rails app I'm creating an array like so:

@messages.each do |message|
  @list << {
    :id => message.id,
    :title => message.title,
    :time_ago => message.replies.first.created_at
  }
end

After making this array I would like to then sort it by time_ago ASC order, is that possible?

and is there any way in which i can change the order i between, i mea any callbacks available for this. Please suggest.

Upvotes: 0

Views: 41

Answers (2)

BroiSatse
BroiSatse

Reputation: 44685

Just do:

@list.sort_by {|hash| hash[:time_ago]}

This will not alter the original array, so you'll need to assign it to some variable. If you want to sort it in place, use banged version sort_by! instead.

Just a note: There is a potential N+1 problem in your code, as your loop may execute an extra SQL query on each repetition. So remember to call @messages.includes(:replies) before looping. Also there might be much faster solution with a proper SQL query. However you need to specify why you want time_age to be the first value for messages in the database - could it be that you want the earliest message instead?

Upvotes: 1

aelor
aelor

Reputation: 11116

final_array = @list.sort {|a,b| a[:time_ago] <=> b[:time_ago]}

should work

Upvotes: 1

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