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mitsuru793/grandchild_total.rb

Last active February 16, 2016 09:02
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Railsで孫レコードの数を取得する
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grandchild_total.rb
# 分かりやすく
blog = Blog.first
article_counts = blog.categories.map { |category| category.articles.count }
article_total = article_counts_counts.sum
# joinsを使う
article_total = Blog.joins(categories: :articles).where(id: 1).count
# 別パターン
blog = Blog.first
article_total = blog.categories.joins(:articles).count
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