Ruby-Rails-SQL查询-搜索词中的单词重新排序

Question

I'm working on a project with a search function that is set up as follows:

if params[:search_term].present? && params[:search_term].length > 1
  @candidates = @candidates.where("title like ?","%#{params[:search_term]}%")
end

The client has asked me to 'loosen up' the search - specifically the word order. At the moment if there is a candidate with a title of White bar stool and one searches for White stool bar , it returns no results.

Is there any way for me to perform a query where word order is ignored? Or would it be better for me to make new search term params with a different word order, do multiple searches, and combine the results?

Answer 1

You may consider using Arel for this. Arel is the underlying query assembler for rails/activerecord (so no new dependencies) and can be very useful when building complex queries because it offers far more depth than the high level ActiveRecord::QueryMethods .

Arel offers a large selection of predication matchers including in your case matches_any and matches_all . These methods take an Array of String s and split them into individual search conditions using Like .

For Example to search for all candidates that contain any of the words searched for you can use:

class Candidate < ActiveRecord::Base
  def self.search_for(term)
    candidates = Candidate.arel_table
    where(
       candidates[:title].lower.matches_any(
          term.split.map { |t| "%#{t.downcase}%" }
       )
    )
  end
end

The end result of search_for (given a search term of 'White stool bar') is:

SELECT [candidates].*
FROM [candidates]
WHERE (
  LOWER([candidates].[title]) LIKE '%white%' 
  OR LOWER([candidates].[title]) LIKE '%stool%' 
  OR LOWER([candidates].[title]) LIKE '%bar%')

Which appears to be what you are looking for. If it must match all the terms you can instead use matches_all which will result in:

SELECT [candidates].*
FROM [candidates]
WHERE (
  LOWER([candidates].[title]) LIKE '%white%' 
  AND LOWER([candidates].[title]) LIKE '%stool%' 
  AND LOWER([candidates].[title]) LIKE '%bar%')

See Here for all the available Arel predications.

This has added benefits of basic escaping to avoid things like SQL injection.

Answer 2

You can use the MySQL RLIKE operator, to match with an specific pattern you can create with your sentence.

sentence = 'White stoll bar'
@candidates = @candidates.where('title RLIKE ?', "(#{sentence.tr(' ', '|')})")