Question

我对Promise和async/await都是陌生的。我有以下代码构成猫鼬查询：

// Bluebird's promise

    const Prom = require('bluebird');

    let formSampleQuery = (customerQuery) => {
     return Prom.try(() => {
      customerQuery.where("age").lt("30");
      console.log("Formed Customer Query Object:\n", customerQuery);
      return Prom.resolve(customerQuery);
     })
    }

然后我有以下使用async/await调用此方法的方法：

let Customer = require('./src/models/customer.model');

exports.executeQuery = () => {
 return Prom.try(async () => {
  let customerQuery = Customer.find().lean();
  customerQuery = await formSampleQuery(customerQuery);
  console.log('Customer Query at Execute Query:\n', customerQuery) // Output coming undefined at this point
  customerQuery.exec().then(res => {console.log(res)}); // At this point I get "TypeError: Cannot read property 'exec' of undefined"
 });
}

我在customerQuery方法中获得了完整的formSampleQuery对象，但是当同一事物返回到executeQuery方法时，它变得不确定，并且出现了这个错误：

TypeError：无法读取未定义的属性“ exec”

我要去哪里错了？

编辑1：

紧随其后的formCustomerQuery查询对象的输出。

Query {
  _mongooseOptions: { lean: true },
  _transforms: [],
  mongooseCollection:
   NativeCollection {
     collection: Collection { s: [Object] },
     opts:
      { bufferCommands: true,
        capped: false,
        '$wasForceClosed': undefined },
     name: 'customers',
     collectionName: 'customers',
   .........................
..........................
........................

  _traceFunction: undefined,
  '$useProjection': true }

我知道这时查询对象具有我指定的条件。它显示在日志中

对Bluebird的诺言使用await将返回未定义的

0 个答案: