title: Mongodb error : The 'cursor' option is required, except for aggregation explain
body: <p>I am using the mongodb 3.5.5 with mongoose 4.9.8 and the Node.js version is 7.10, when I publish my app to production server, the error was happened, but in my develop environment is work.</p>
  
  <p>How can I fix them?</p>
  
  <p>The error message:</p>
  
  <pre><code>{ MongoError: The 'cursor' option is required, except for aggregation explain
       at Function.MongoError.create (/data/deploy/aaa/webapp/node_modules/mongodb-core/lib/error.js:31:11)
       at /data/deploy/aaa/webapp/node_modules/mongodb-core/lib/connection/pool.js:489:72
       at authenticateStragglers (/data/deploy/aaa/webapp/node_modules/mongodb-core/lib/connection/pool.js:435:16)
       at Connection.messageHandler (/data/deploy/aaa/webapp/node_modules/mongodb-core/lib/connection/pool.js:469:5)
       at Socket.&lt;anonymous&gt; (/data/deploy/aaa/webapp/node_modules/mongodb-core/lib/connection/connection.js:321:22)
       at emitOne (events.js:96:13)
       at Socket.emit (events.js:191:7)
       at readableAddChunk (_stream_readable.js:178:18)
       at Socket.Readable.push (_stream_readable.js:136:10)
       at TCP.onread (net.js:561:20)
     name: 'MongoError',
     message: 'The \'cursor\' option is required, except for aggregation explain',
     ok: 0,
     errmsg: 'The \'cursor\' option is required, except for aggregation explain',
     code: 9,
     codeName: 'FailedToParse' }
  </code></pre>
  
  <p>js code:</p>
  
  <pre><code>  articleLikeSchema.statics.sumById = function ({id = ''} = {}) {
      return this.model('ArticleLike').aggregate([
        { $match: { id: id } },
        { $group: { _id: '$id', count: { $sum: 1 } } }
      ]).then(sum =&gt; {
        if (!sum || sum.length === 0) return Promise.resolve({count: 0})
        else return Promise.resolve(sum[0])
      })
    }
  </code></pre>
  
  <p>The Mongoose execute command:</p>
  
  <pre><code>Mongoose: articlelikes.aggregate([ { '$match': { id: '1494606935' } }, { '$group': { _id: '$id', count: { '$sum': 1 } } } ], {})
  </code></pre>