使用 ES7 async/await 获取 Knex.js 事务 [英] Get Knex.js transactions working with ES7 async/await

问题描述

我正在尝试将 ES7 的 async/await 与 knex.js 事务结合起来.

I'm trying to couple ES7's async/await with knex.js transactions.

虽然我可以轻松地使用非事务性代码，但我很难使用上述 async/await 结构使事务正常工作.

Although I can easily play around with non-transactional code, I'm struggling to get transactions working properly using the aforementioned async/await structure.

我正在使用这个模块来模拟异步/等待

这是我目前拥有的:

工作正常但不是事务性的

// assume `db` is a knex instance

app.post("/user", async((req, res) => {
  const data = {
   idUser: 1,
   name: "FooBar"
  }

  try {
    const result = await(user.insert(db, data));
    res.json(result);
  } catch (err) {
    res.status(500).json(err);
  }
}));

user.js

insert: async (function(db, data) {
  // there's no need for this extra call but I'm including it
  // to see example of deeper call stacks if this is answered

  const idUser =  await(this.insertData(db, data));
  return {
    idUser: idUser
  }
}),

insertData: async(function(db, data) {
  // if any of the following 2 fails I should be rolling back

  const id = await(this.setId(db, idCustomer, data));
  const idCustomer = await(this.setData(db, id, data));

  return {
    idCustomer: idCustomer
  }
}),

// DB Functions (wrapped in Promises)

setId: function(db, data) {
  return new Promise(function (resolve, reject) {
    db.insert(data)
    .into("ids")
    .then((result) => resolve(result)
    .catch((err) => reject(err));
  });
},

setData: function(db, id, data) {
  data.id = id;

  return new Promise(function (resolve, reject) {
    db.insert(data)
    .into("customers")
    .then((result) => resolve(result)
    .catch((err) => reject(err));
  });
}

尝试使其具有交易性

user.js

// Start transaction from this call

insert: async (function(db, data) {
 const trx = await(knex.transaction());
 const idCustomer =  await(user.insertData(trx, data));

 return {
    idCustomer: idCustomer
  }
}),

似乎 await(knex.transaction()) 返回此错误:

[TypeError: container is not a function]

推荐答案

Async/await 基于 promises，所以看起来你只需要包装所有 knex 方法来返回promise compatible"对象.

Async/await is based around promises, so it looks like you'd just need to wrap all the knex methods to return "promise compatible" objects.

这里描述了如何将任意函数转换为与 Promise 一起使用，以便它们可以与 async/await 一起使用:

Here is a description on how you can convert arbitrary functions to work with promises, so they can work with async/await:

尝试了解如何使用 BlueBird 进行承诺

基本上你想这样做:

var transaction = knex.transaction;
knex.transaction = function(callback){ return knex.transaction(callback); }

这是因为async/await 需要一个带有单个回调参数的函数，或者一个 promise"，而 knex.transaction 看起来像这样:

This is because "async/await requires the either a function with a single callback argument, or a promise", whereas knex.transaction looks like this:

function transaction(container, config) {
  return client.transaction(container, config);
}

或者，您可以创建一个新的 async 函数并像这样使用它:

Alternatively, you can create a new async function and use it like this:

async function transaction() {
  return new Promise(function(resolve, reject){
    knex.transaction(function(error, result){
      if (error) {
        reject(error);
      } else {
        resolve(result);
      }
    });
  });
}

// Start transaction from this call

insert: async (function(db, data) {
 const trx = await(transaction());
 const idCustomer =  await(person.insertData(trx, authUser, data));

 return {
    idCustomer: idCustomer
  }
})

这也可能很有用:Knex Transaction with Promises

(另外请注意，我对 knex 的 API 不熟悉，所以不确定传递给 knex.transaction 的参数是什么，以上只是举例).

(Also note, I'm not familiar with knex's API, so not sure what the params are passed to knex.transaction, the above ones are just for example).

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