意外拒绝错误:交易查询已完成-knex，express.js

问题描述：

我试图先检查表中的值，如果该值存在，请删除另一个表中的行，并将新数据插入该表中.

I was trying to check for a value in a table first, and if it exists, delete a row in another table and insert this new data into that table.

我使用了带有select，del()和插入命令的事务

I used a transaction with a select, del(), and a insert command

db.transaction(trx => {
  return trx('users')
    .where({ username: user.username })
    .select('username')
    .returning('username')

    .then(retData => {
      retUserName = retData[0];

      db('profile')
        .where({ username: user.username })
        .del()
        .then(retData => {
          return trx
            .insert(profileData)
            .into('profile')
            .returning('*');
        });
    })
    .then(retData => {
      res.json({ ProfileData: profileData });
    })
    .then(trx.commit)
    .catch(trx.rollback);
}).catch(err => res.status(400).json('unable to create profile'));

我收到此错误拒绝拒绝错误:交易查询已完成

I get this error Unhanded rejection error:Transaction query already completed

但数据尚未添加到表中.

but the data hasn't been added to the table.

答

您正在从事务处理程序回调中返回承诺，这将导致事务自动落实/回退，具体取决于返回的承诺是否解决/拒绝.

You are returning promise from transaction handler callback, which causes transaction to automatically committed / rolled back depending if returned promise resolves / rejects.

https://knexjs.org/#Transactions

直接从事务处理程序函数引发错误自动回滚交易，就像返回被拒绝的交易一样答应.

Throwing an error directly from the transaction handler function automatically rolls back the transaction, same as returning a rejected promise.

请注意，如果处理程序中未返回承诺，则承诺已完成给您以确保调用trx.commit或trx.rollback，否则事务连接将挂起.

Notice that if a promise is not returned within the handler, it is up to you to ensure trx.commit, or trx.rollback are called, otherwise the transaction connection will hang.

在您的代码中，您混用了这两种使用事务的方式，这导致它被提交/回滚两次.

In your code you are mixing those two different ways to use transactions, which causes it to be committed / rolledback twice.

意外拒绝错误:交易查询已完成-knex，express.js

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