$查找多个级别没有$展开？

Question

$查找多个级别没有$展开？我有以下收藏场地收集{     "_id" : ObjectId("5acdb8f65ea63a27c1facf86"),     "name" : "ASA College - Manhattan Campus",     "addedBy" : ObjectId("5ac8ba3582c2345af70d4658"),     "reviews" : [          ObjectId("5acdb8f65ea63a27c1facf8b"),          ObjectId("5ad8288ccdd9241781dce698")     ]}评论集{     "_id" : ObjectId("5acdb8f65ea63a27c1facf8b"),     "createdAt" : ISODate("2018-04-07T12:31:49.503Z"),     "venue" : ObjectId("5acdb8f65ea63a27c1facf86"),     "author" : ObjectId("5ac8ba3582c2345af70d4658"),     "content" : "nice place",     "comments" : [          ObjectId("5ad87113882d445c5cbc92c8")     ],}评论集{     "_id" : ObjectId("5ad87113882d445c5cbc92c8"),     "author" : ObjectId("5ac8ba3582c2345af70d4658"),     "comment" : "dcfdsfdcfdsfdcfdsfdcfdsfdcfdsfdcfdsfdcfdsfdcfdsf",     "review" : ObjectId("5acdb8f65ea63a27c1facf8b"),     "__v" : 0}作者收藏{     "_id" : ObjectId("5ac8ba3582c2345af70d4658"),     "firstName" : "Bruce",     "lastName" : "Wayne",     "email" : "[e-mail]",     "followers" : [ObjectId("5ac8b91482c2345af70d4650")]}现在，我的以下填充查询运行良好    const venues = await Venue.findOne({ _id: id.id })     .populate({       path: 'reviews',       options: { sort: { createdAt: -1 } },       populate: [         {  path: 'author'  },         {  path: 'comments', populate: [{ path: 'author' }] }       ]     })但我想用$lookup质疑，但当我对评论做“$Unout”时，它会把场地分割开来.我想要在相同的数组(如填充)和相同的顺序.我想实现以下查询$lookup因为作者有追随者字段，所以我需要发送字段isFollow通过做$project不能使用populate...$project: {     isFollow: { $in: [mongoose.Types.ObjectId(req.user.id), '$followers'] }}