json2csv无法正常使用猫鼬聚合

Question

我有以下代码

    const fs = require('fs');
    const { Transform } = require('json2csv');
    const { UserModel } = require('./models/user.model');

    const users = UserModel.aggregate([
      {
        $sort: {
          _id: -1,
        },
      },
      {
        $limit: 100,
      },
      {
        $project: {
          _id: 0,
          fullName: 1,
          mobile: 1,
        },
      },
    ]).cursor().exec();

    const fields = ['fullName', 'mobile'];
    const opts = { fields };
    const transformOpts = { highWaterMark: 16384, encoding: 'utf-8' };

    // const input = fs.createReadStream('./public/users.json', { encoding: 'utf8' });

    const output = fs.createWriteStream('./public/data.csv', { encoding: 'utf8' });
    const json2csv = new Transform(opts, transformOpts);

    const processor = users.pipe(json2csv).pipe(output);

如果执行此查询，则data.csv文件仅包含

"fullName","mobile"

，但如果来自静态json文件的管道，即user.json，则data.csv包含所有行。我做错了什么？有什么主意吗？