Postモデルから、search_wordsに含まれる単語をAND検索する ref: http://qiita.com/ppworks/items/4de9e7dc324aad2c9f48

file1.diff

-     arel_cond.and(condition)
+     arel_cond.or(condition)

post.rb

  scope :search, ->(search_words) {
    return if search_words.empty?
    post_arel = Post.arel_table[:content]
    conditions = search_words.map { |word| post_arel.matches("%#{word}%") }
    where_clauses = conditions.inject do |arel_cond, condition|
      arel_cond.and(condition)
    end
    where(where_clauses)
  }