ruby-on-rails - 如果为真，Rails 会将字符串合并到现有字符串

Question

我正在使用 gem prawn 生成 PDF。我想使用该 gem 创建表，因此我make_cell将从该 gem 中使用，如下所示：

  make_cell(
    content: "#{cash_transaction[:transaction_date]}
              \n#{cash_transaction[:creation_date]}
              \n#{cash_transaction[:deletion_date]}"
  )

问题是什么时候deletion_date(cash_transaction)它会打印我们creation_date和空行（来自\n#{cash_transaction[:deletion_date]}. 如何以比下面更优雅的方式防止这种情况：

  if cash_transaction[:deletion_date]
    make_cell(
      content: "#{cash_transaction[:transaction_date]}
                \n#{cash_transaction[:creation_date]}
                \n#{cash_transaction[:deletion_date]}"
    )
  else
    make_cell(
      content: "#{cash_transaction[:transaction_date]}
                \n#{cash_transaction[:creation_date]}"
    )
  end

Answer 1

我建议您将字符串构建为然后将其传递给make_cell

content = "#{cash_transaction[:transaction_date]}
           \n#{cash_transaction[:creation_date]}"

content << "\n#{cash_transaction[:deletion_date]} if cash_transaction[:deletion_date]

make_cell(content: content)

Answer 2

这个怎么样：

deletion = cash_transaction[:deletion_date]
deletion = deletion ? "\n#{deletion}" : ''

make_cell(
  content: "#{cash_transaction[:transaction_date]}
            \n#{cash_transaction[:creation_date]}
            #{deletion}"
)