Question

I have the following method which creates and then executes an SQL query:

def edition_authors(edition, authors)
  query_string = "contributor_type = ? AND author = ?"
  for i in 1..authors.length - 1
    query_string += " OR author = ?"
  end
  return edition.contributors.where(query_string, 'Author', authors)
end

The last line is the one I’m having trouble with. I want the ‘authors’ array to somehow turn into a set of strings. For instance, if the authors array contained [‘James Joyce’, ‘Cory Doctorow’, ‘Cormac McCarthy’], I’d like that last line to read like:

return edition.contributors.where(query_string, 'Author', 'James Joyce', 'Cory Doctorow', 'Cormac McCarthy')

How could I accomplish this?

Answer 1

Depends which rails and which ruby you are using,

1. ActiveRecord already has this functionality in Rails 3: Model.where(:my_field => ['Author', 'James Joyce', 'Cory Doctorow', 'Cormac McCarthy'])

2. arr.map{|v| v.to_s.inspect} will get you a comma separated list

3. arr.join(',') will give you a comma separated list, no quotes.

Then you can use this string however you wish.