javascript - 返回时无法从 promise 中获取值(value)

Question

我有一个函数可以获取特定时间段内的数据总和

  const cashData = db.query(`SELECT SUM (payments_log.amount_paid) FROM payments_log WHERE payments_log.payment_method = '2' AND payments_log.inserted_at BETWEEN $1 AND NOW() `, [date])
.then(records => {
  return records[0].sum
})
.catch(error => {
  cb(new Error(`Print failed: ${error}`))
})

但是当我运行它时，我的结果是[对象 promise ]。这是为什么？

Answer 1

您需要等到 promise 完成:

  const cashData = db.query(`SELECT SUM (payments_log.amount_paid) FROM payments_log WHERE payments_log.payment_method = '2' AND  payments_log.inserted_at BETWEEN $1 AND NOW() `, [date])
   .then(records => {
     return records[0].sum
 })
  .catch(error => {
    cb(new Error(`Print failed: ${error}`))
 });

 cashData.then(res => console.log(res));

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