NestJS中使用Bluebird.map报错TypeError的问题求助

环境信息 #

• @nestjs/core 9.0.0
• bluebird 3.7.2
• @types/bluebird 3.5.38

tsconfig.json 配置 #

{
  "compilerOptions": {
    "module": "commonjs",
    "declaration": true,
    "removeComments": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "target": "es2017",
    "sourceMap": true,
    "outDir": "./dist",
    "baseUrl": "./",
    "incremental": true,
    "skipLibCheck": true,
    "strictNullChecks": false,
    "noImplicitAny": false,
    "strictBindCallApply": false,
    "forceConsistentCasingInFileNames": false,
    "noFallthroughCasesInSwitch": false,
    "esModuleInterop": true
  }
}

报错代码 #

await Bluebird.map(dataAccessories, accessory => {
    const { accessory_id, quantity } = accessory
    return Accessory.update({
        where: { id: accessory_id },
        data: {
            inventory: {
                increment: quantity
            }
        }
    })
}, { concurrency: 5 })

错误信息 #

TypeError: obj._then is not a function

  at tryConvertToPromise (node_modules/bluebird/js/release/thenables.js:19:21)
  at MappingPromiseArray._promiseFulfilled (node_modules/bluebird/js/release/map.js:81:28)
  at MappingPromiseArray.PromiseArray._iterate (node_modules/bluebird/js/release/promise_array.js:115:31)
  at MappingPromiseArray.init (node_modules/bluebird/js/release/promise_array.js:79:10)
  at MappingPromiseArray._asyncInit (node_modules/bluebird/js/release/map.js:37:10)
  at _drainQueueStep (node_modules/bluebird/js/release/async.js:97:12)
  at _drainQueue (node_modules/bluebird/js/release/async.js:86:9)
  at Async.Object.<anonymous>.Async._drainQueues (node_modules/bluebird/js/release/async.js:102:5)
  at Immediate.Async.drainQueues (node_modules/bluebird/js/release/async.js:15:14)

解决方法 #

这个错误的核心是Bluebird无法识别Accessory.update返回的Promise对象——Bluebird内部依赖私有属性_then判断是否为可处理的Promise，而你使用的ORM返回的可能是原生Promise或自定义Promise，不具备该属性。以下是三种可行方案：

方案1：将ORM返回值转为Bluebird Promise #

用Bluebird.resolve()包裹ORM的返回结果，强制转为Bluebird兼容的Promise：

await Bluebird.map(dataAccessories, accessory => {
    const { accessory_id, quantity } = accessory
    return Bluebird.resolve(Accessory.update({
        where: { id: accessory_id },
        data: {
            inventory: {
                increment: quantity
            }
        }
    }))
}, { concurrency: 5 })

方案2：改用原生Promise实现并发控制 #

如果不需要Bluebird的特定功能，可直接用原生Promise结合分批逻辑实现并发控制：

const concurrency = 5;
// 分批执行，控制并发数
for (let i = 0; i < dataAccessories.length; i += concurrency) {
    const batch = dataAccessories.slice(i, i + concurrency);
    await Promise.all(batch.map(accessory => {
        const { accessory_id, quantity } = accessory
        return Accessory.update({
            where: { id: accessory_id },
            data: {
                inventory: {
                    increment: quantity
                }
            }
        })
    }));
}

方案3：配置ORM使用Bluebird作为Promise库 #

部分ORM支持指定Promise库，以TypeORM为例，可在配置中直接设置使用Bluebird：

// TypeORM配置示例
{
    type: 'mysql',
    host: 'localhost',
    port: 3306,
    // ...其他数据库配置
    promiseLibrary: require('bluebird')
}

配置后ORM返回的就是Bluebird Promise，可直接被Bluebird.map识别处理。

内容的提问来源于stack exchange，提问作者XanhZ