Question

I’m trying to return results more like the search

My curren algorithm is this

def search_conditions(column, q)
  vars  = []
  vars2 = []

  vars << q

  if q.size > 3
    (q.size-2).times do |i|
      vars2 << q[i..(i+2)]
      next if i == 0
      vars << q[i..-1]
      vars << q[0..(q.size-1-i)]
      vars << q[i % 2 == 0 ? (i/2)..(q.size-(i/2)) : (i/2)..(q.size-1-(i/2))] if i > 1
    end
  end

  query = "#{column} ILIKE ?"
  vars = (vars+vars2).uniq

  return [vars.map { query }.join(' OR ')] + vars.map { |x| "%#{x}%" }
end

If I search for “Ruby on Rails” it will make 4 search ways.

1) Removing the left letters “uby on Rails”..”ils”

2) Removing the right letters “Ruby on Rail”..”Rub”

3) Removing left and right letters “uby on Rails”, “uby on Rail” … “on “

4) Using only 3 letters “Rub”, “uby”, “by “, “y o”, ” on” … “ils”

Is good to use these 4 ways? There any more?

Answer 1

Why are you removing these letters? Are you trying to make sure that if someone searches for ‘widgets’, you will also match ‘widget’?

If so, what you are trying to do is called ‘stemming‘, and it is really much more complicated than removing leading and trailing letters. You may also be interested in removing ‘stop words‘ from your query. These are those extremely common words that are necessary to form grammatically-correct sentences, but are not very useful for search, such as ‘a’, ‘the’, etc.

Getting search right is an immensely complex and difficult problem. I would suggest that you don’t try to solve it yourself, and instead focus on the core purpose of your site. Perhaps you can leverage the search functionality from the Lucene project in your code. This link may also be helpful for using Lucene in Ruby on Rails.

I hope that helps; I realize that I sort of side-stepped your original question, but I really would not recommend trying to tackle this yourself.