Question

试图找出在expressjs中使用Sequelize事务的正确方法。以下代码通过ID查找帖子，从而增加帖子表中的回复计数，更新帖子，然后在回复表中创建回复。试图在控制器操作中调用代码，但它不起作用。内部承诺没有兑现。关于在Sequelize中使用交易的正确方法有何建议？

Sequelize.transaction(function (t) {  
db.Post.find({where:{id: postId}}, {transaction:t}).then(function(post)
{
  var count = post.reply + 1; 
  post.update({replyCount:count},{transaction:t});
  db.Reply.create(replyData, {transaction:t}).then(function(newcomment, created){      
          res.json(newcomment);

      });     
});
  }).then(function (result) {
// Transaction has been committed
// result is whatever the result of the promise chain returned to the transaction callback 
 }).catch(function (err) {
// Transaction has been rolled back
// err is whatever rejected the promise chain returned to the transaction 
});        
});

Answer 1

Sequelize.transaction(function (t) {  
 return db.Post.find({where:{id: postId}}, {transaction:t}).then(function(post)
{
  var count = post.reply + 1; 
  return post.update({replyCount:count},{transaction:t})
         .success(result =>
              // i guess you want to use result in here to create replyData
              return db.Reply.create(replyData, {transaction:t})

                     .then(function(newcomment, created){      
                           return res.json(newcomment);

                      }); 
         );

});

Answer 2

在事务中的初始.find（）没有任何价值。在回滚的情况下，没有什么可以撤消的。仅写入或更新需要在事务中回滚。 try / catch将处理任何失败的查询，并且将自动为事务项触发回滚。

考虑这个更现代的ES6解决方案：

try {

  const result = await sequelize.transaction(async (t) => {

    // no need to include this in the transaction, it only reads (find)
    const post = await db.Post.find({where:{id: postId}});

    const count = post.reply + 1;
    const updateResult = await post.update({
      replyCount: count
    }, { transaction: t });

    // i guess you want to use result in here to create replyData
    const createResult = await db.Reply.create({
      replyData,
    }, { transaction:t });

    return res.json(newcomment);
  });

} catch (error) {

  // If the execution reaches this line, an error occurred.
  // The transaction has already been rolled back automatically by Sequelize!

}

参考： -https://sequelize.org/master/manual/transactions.html#managed-transactions

加速expressjs中的事务未执行

2 个答案: