transactions - bluebird node-mysql2事务

Question

一直在尝试 promisify node-mysql2 事务，但无法让它工作，有什么指示吗？

我已经阅读了 http://bluebirdjs.com/docs/api/disposer.html 上的文档

我也有非交易相关代码的工作版本，但是让交易正常工作，以及适当的资源处置和错误处理一直很困难。这是从 node-mysql api 文档中获取的基于回调的实现

connection.beginTransaction(function(err) {
  if (err) { throw err; }
  connection.query('INSERT INTO posts SET title=?', title, function(err, result) {
    if (err) {
      return connection.rollback(function() {
        throw err;
      });
    }

    var log = 'Post ' + result.insertId + ' added';

    connection.query('INSERT INTO log SET data=?', log, function(err, result) {
      if (err) {
        return connection.rollback(function() {
          throw err;
        });
      }  
      connection.commit(function(err) {
        if (err) {
          return connection.rollback(function() {
            throw err;
          });
        }
        console.log('success!');
      });
    });
  });
});

这是我对查询管理的实现

import { mysqldb } from '../config';
import { createPool } from 'mysql2';
import Pool from 'mysql2/lib/pool';
import Connection from 'mysql2/lib/connection';
import { using, promisifyAll, try as promiseTry } from 'bluebird';

promisifyAll([Pool, Connection]);
const pool = createPool(mysqldb);

export const getConnection = () =>
  pool.getConnectionAsync().disposer(connection =>
      connection.release());

export const withTransaction = (fn) =>
  using(getConnection(), tx =>
    promiseTry(fn(tx), tx.beginTransaction()).then(
      res => tx.commitAsync().catch(e => e).thenReturn(res),
      err => tx.rollbackAsync().catch(e => e).thenThrow(err)
    )
);

// withTransaction(tx =>
//   tx.executeAsync('sql1')
//     .then(tx.executeAsync('sql2'))
//     .then(tx.executeAsync('sql3'))
//     .then(tx.executeAsync('sql4'))
// );

export const query = (sql, params) =>
  using(getConnection(), connection =>
    connection.executeAsync(sql, params)
  );

然而交易给了我

Unhandled rejection TypeError: expecting a function but got [object Object]
    at apiRejection (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/promise.js:10:27)
    at Promise.attempt.Promise.try (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/method.js:26:16)
    at /Users/willh/workspace/ChenPin/graphql/lib/services/mysql.js:35:30
    at tryCatcher (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/util.js:16:23)
    at /Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/using.js:184:26
    at tryCatcher (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/util.js:16:23)
    at Promise._settlePromiseFromHandler (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/promise.js:503:31)
    at Promise._settlePromise (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/promise.js:560:18)
    at Promise._settlePromise0 (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/promise.js:605:10)
    at Promise._settlePromises (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/promise.js:684:18)
    at Promise._fulfill (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/promise.js:629:18)
    at PromiseArray._resolve (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/promise_array.js:125:19)
    at PromiseArray._promiseFulfilled (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/promise_array.js:143:14)
    at Promise._settlePromise (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/promise.js:565:26)
    at Promise._settlePromise0 (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/promise.js:605:10)
    at Promise._settlePromises (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/promise.js:684:18)
    at Promise._fulfill (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/promise.js:629:18)
    at Promise._resolveCallback (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/promise.js:424:57)
    at Promise._settlePromiseFromHandler (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/promise.js:515:17)
    at Promise._settlePromise (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/promise.js:560:18)
    at Promise._settlePromise0 (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/promise.js:605:10)
    at Promise._settlePromises (/Users/willh/workspace/ChenPin/graphql/node_modules/bluebird/js/release/promise.js:684:18)

什么是正确的方法？

更新:

通过查看源代码让它工作，结果发现它只是一个简单的助手，真的不值得使用他们的助手，下面是最终的工作版本。无论如何感谢您的帮助:D

export const withTransaction = (fn) =>
  using(getConnection(), tx =>
    tx.queryAsync('START TRANSACTION').then(fn(tx)).then(
      res => tx.queryAsync('COMMIT').thenReturn(res),
      err => tx.queryAsync('ROLLBACK').catch(e => e).thenThrow(err)
    )
  );

// withTransaction(tx =>
//   tx.executeAsync('select :x + :y as z', { x: 1, y: 2 }).then(res1 =>
//   tx.executeAsync('select :x + :y as z', { x: res1[0].z, y: 1 })).then(res2 =>
//   tx.executeAsync('select :x + :y as z', { x: res2[0].z, y: 1 })).then(res3 =>
//   tx.executeAsync('select :x + :y as z', { x: res3[0].z, y: 1 })).then(res4 => res4)
// );

顺便说一句，原来的 promisify 方法是有效的，没有什么区别，但感谢您帮助我!

Answer 1

您遇到错误是因为 promisifyAll 使用的是函数而不是对象。在大多数情况下，函数存在于类的 prototype 中。试试这个

var Promise = require('bluebird');
var mysql = require('mysql2');
Promise.promisifyAll(mysql.Connection.prototype);
Promise.promisifyAll(require('mysql2/lib/pool').prototype)

在我上面的练习示例中，效果很好。

如果你觉得你想在这个领域做更多的实验，你也可以手动遍历所有元素并只选择函数，就像我个人在 Postgres 中使用的下面的例子

var Promise = require('bluebird');
var pg = require('pg');
Object.keys(pg).forEach(function (key) {
  var Cls = null;
  try {
    Cls = pg[key];
    if (typeof Cls === 'function') {
      Promise.promisifyAll(Cls.prototype);
      Promise.promisifyAll(Cls);
    }
  } catch (e) {
    console.log(e);
  }
});
Promise.promisifyAll(pg);