在Rails3中搜索链接的模型

Question

After following the railscast for creating a search engine, my code looks like this for search titles, and descriptions of posts:

  def self.search(search)
    if search
      where("LOWER (description) LIKE ? OR LOWER (title) LIKE ?", "%#{search.downcase}%" , "%#{search.downcase}%")
    else
      scoped
    end
  end

The post table, has_many tags though, and I'd like this search query to search tags as well. Is this possible?

Answer 1

Try

  def self.search(search)
    if search
      includes(:tags).where("LOWER (description) LIKE ? OR LOWER (title) LIKE ? OR tags.name LIKE ?", "%#{search.downcase}%" , "%#{search.downcase}%", "%#{search.downcase}%")
    else
      scoped
    end
  end

This will do a LIKE on the name property of the tags. Edit it to suit your needs.

Answer 2

Recommend having a tag_list stored on the post model itself, which will make searching trivial. @Dogbert's answer works just as well, the following contains the query to one table.

def post
  before_update :set_tag_list

  def set_tag_list
    self.tag_list = tags.map{|tag| tag.name}.join(', ')
  end
end

Then you can include the tag_list in your search query and not have to join many models together.