覚えておくと幸せになれるActiveRecord::Relationメソッド6選 ref: http://qiita.com/Yama-to/items/4696e9d43ebec6012129

百聞は一見に如かず

book_data = {title: "Frozen", author: "Charles Dickens"}
book_review = {rate: 10, review: "Awesome!"}

book_data.merge(book_review)

# => {title: "Frozen", author: "Charles Dickens", rate: 10, review: "Awesome!"}