如何循环多行 sql 查询并在 Knex Transactions 中使用它们？

Question

这里的 Node 和 Knex 新手来自 RoR 背景，我需要将特定函数转换为 Node.js

这是我的 RoR 代码：

  def self.save!
    update_queries = self.fetch.map{|currency, rate|
      "UPDATE currency_exchange_rates SET rate='#{rate}' WHERE currency='#{currency}'"
    }.join(';')

    ActiveRecord::Base.connection.execute(update_queries)
  end

到目前为止，这是我在 Nodejs 中的内容：

static save(new_rates){
      return new Promise(async (resolve, reject) => {
        var query = Object.keys(rate).map(key => 'UPDATE currency_exchange_rates SET rate=' + rate[key] + ' WHERE currency = "' + key + '"').join('; ');
    })
  }

输入数据如下所示：

新利率 =

'UPDATE currency_exchange_rates SET rate=32102793.12 WHERE currency= "IDR"; 

UPDATE currency_exchange_rates SET rate=0.7822 WHERE currency= "USDGBP"; 

UPDATE currency_exchange_rates SET rate=3189.756317 WHERE currency= "CAD"; 

UPDATE currency_exchange_rates SET rate=152.8 WHERE currency= "USDLKR"; 

UPDATE currency_exchange_rates SET rate=110.818 WHERE currency= "USDJPY"; 

UPDATE currency_exchange_rates SET rate=1.3103 WHERE currency= "USDAUD"'

我正在使用 Knex.js 连接到我的 pg 数据库。如何使用 knex 执行所有这些操作？我可以只传递 knex.raw() 中的所有查询吗？ knex.transaction()怎么样？它们有什么区别？

提前致谢！

Answer 1

像这样的方法很有效：

let retVal = await knex.transaction(async (trx) => {
  for (let key of Object.keys(rate)) {
    let value = rate[key];
    await trx('currency_exchange_rates')
      .update({ rate: value }).where('currency', key);
  }
  return "woo done"; // this value is returned from transaction 
});

在处理事务时，通常您希望一个一个地创建和运行查询，以避免在通过事务的单个数据库连接运行连接它们之前对查询进行不必要的缓冲。

Answer 2

// [Sequential Update] Commit transaction after each successfully executed query
await knex.transaction(async trx => {
    return Promise.all(Object.keys(rate).map(key => trx('currency_exchange_rates')
            .update({ rate: rate[key] })
            .where({ currency: key })
    ));
});

// [Bulk Update] Commit transaction after all queries have been executed successfully
await knex.transaction(trx => {
    return Promise.all(Object.keys(rate).map(key => knex('currency_exchange_rates')
            .update({ rate: rate[key] })
            .where({ currency: key })
        ))
        .then(trx.commit)
        .catch(trx.rollback);
});

如何循环多行 sql 查询并在 Knex Transactions 中使用它们？

How to loop through multi-line sql query and use them in Knex Transactions?

node.js

knex.js