Rails 3: Sorting by many strings

Question

I have multiple strings that are all number values. They are all inside the same db table. Is there a way to join them all and sort by the highest number?

Something like (pseudo code):

:include => :word_one_value, :word_two_value, :word_three_value, :sort_by => "sum ASC"

Why do you have string values that are actually numbers in first place? — Ismael
– Ismael, Commented Jul 8, 2012 at 17:40
@ismaelga I'm still learning. I've got many other strings and these are number values to them. For instance I've got :word_one, :word_two, :word_three -- these are the numbers that go along with them without creating overgrown tables in the db. — Patrick A.
– Patrick A., Commented Jul 8, 2012 at 17:44

Mori · Accepted Answer · 2012-07-08 18:02:45Z

1

In MySql:

Foo.order '(convert(word_one, unsigned) +
            convert(word_two, unsigned) +
            convert(word_three, unsigned))'

In ActiveRecord:

Foo.all.sort_by do |f| 
  %w[one two three].sum { |n| f.send("word_#{n}").to_i } 
end

Or if these fields are inside Foo:

class Foo < ActiveRecord::Base
    def self.sorted_by_sum_of_words
      order '(convert(word_one, unsigned) +
              convert(word_two, unsigned) +
              convert(word_three, unsigned))'
    end
end

Then in the controller:

class FooController < ApplicationController
  def my_action
    @foos = Foo.sorted_by_sum_of_words        
  end
end

The conversions are unnecessary if you store numbers in number columns.

edited Jul 8, 2012 at 18:02

answered Jul 8, 2012 at 16:45

Mori

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1 Comment

Patrick A. Over a year ago

Can you give me an example? I appreciate it! I can't seem to figure out the second ActiveRecord example inside my controller action. My controller action looks like this: @ethos = user.ethos

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