node.js - Mongodb 错误 : The 'cursor' option is required, 除了使用解释参数进行聚合之外 mongodb 3.6

Question

Mongodb(版本 3.6)聚合不起作用。之前我使用的是 mongodb 3.4 和 mongoose 4.7.0。

Books.aggregate([{
            $match: filter
        }, {
            $lookup: {
                from: 'users',
                localField: 'user_id',
                foreignField: '_id',
                as: 'user'
            }
        }], function(err, list) {

上面的代码在 mongodb 3.4 上运行良好。但是将 mongodb 更新到 3.6 后，聚合不起作用。它抛出以下错误

The 'cursor' option is required, except for aggregate with the explain argument

由于许多依赖项，我也无法更新 Mongoose 。那么 mongoose 4.7.0 有什么办法可以解决这个问题吗？

Answer 1

AGGREGATIONCURSOR Cannot directly be instantiated

示例

const MongoClient = require('mongodb').MongoClient;
const test = require('assert');
// Connection url
const url = 'mongodb://localhost:27017';
// Database Name
const dbName = 'test';
// Connect using MongoClient
MongoClient.connect(url, function(err, client) {
  // Create a collection we want to drop later
  const col = client.db(dbName).collection('createIndexExample1');
  // Insert a bunch of documents
  col.insert([{a:1, b:1}
    , {a:2, b:2}, {a:3, b:3}
    , {a:4, b:4}], {w:1}, function(err, result) {
    test.equal(null, err);
    // Show that duplicate records got dropped
    col.aggregation({}, {cursor: {}}).toArray(function(err, items) {
      test.equal(null, err);
      test.equal(4, items.length);
      client.close();
    });
  });
});