Sanitize SQL in custom conditions

Question

I need to create a simple search but I can't afford to use Sphinx.

Here's what I wrote:

keywords = input.split(/\s+/)
queries = []

keywords.each do |keyword|
  queries << sanitize_sql_for_conditions(
              "(classifications.species LIKE '%#{keyword}%' OR 
               classifications.family LIKE '%#{keyword}%' OR 
               classifications.trivial_names LIKE '%#{keyword}%' OR
               place LIKE '%#{keyword}%')")
end

options[:conditions] = queries.join(' AND ')

Now, sanitize_sql_for_conditions does NOT work! It returns simply returns the original string.

How can I rewrite this code to escape malicious code?

Answer 1

If you replace the "#{keyword}" with a "?", you can do something like this. Using the question mark will automatically sanitize SQL.

keywords = input.split(/\s+/)
queries = []
vars = []

keywords.each do |keyword|
  queries << "(classifications.species LIKE '%?%' OR 
               classifications.family LIKE '%?%' OR 
               classifications.trivial_names LIKE '%?%' OR
               place LIKE '%?%')"
  vars = vars << keyword << keyword << keyword << keyword
end

options[:conditions] = [queries.join(' AND '), vars].flatten

Answer 2

I use a lot of custom conditions in ActiveRecord, but I like to package them in an array of condition arrays, then combine 'em, using the ? value lets AR santize them automatically:

conditions = Array.new
conditions << ["name = ?", "bob"]
conditions << ["(created_at > ? and created_at < ?)", 1.year.ago, 1.year.from_now]  

User.find(:first, :conditions => combine_conditions(conditions))

 def combine_conditions(somearray) # takes an array of condition set arrays and reform them into a AR-compatible condition array
   conditions = Array.new
   values = Array.new
   somearray.each do |conditions_array|
     conditions << conditions_array[0] # place the condition in an array
     # extract values
     for i in (1..conditions_array.size - 1)
       values << conditions_array[i]
     end 
   end
   [conditions.join(" AND "), values].flatten
 end