尝试执行 $lookup 和 $unwind 时，Mongodb 聚合不返回任何内容

Question

我正在尝试根据chatroomId 获取消息并返回该聊天室中的所有消息，并从userId 添加有关用户的所有数据。我尝试了以下方法，但它返回一个空数组。

我做错了什么？

chatMessageSchema.statics.getConversationByRoomId = async function (
  chatRoomId,
  options = {}
) {
  try {
    return this.aggregate([
      { $match: { chatRoomId } },
      { $sort: { createdAt: -1 } },

      {
        $lookup: {
          from: "User",
          localField: "userId",
          foreignField: "_id",
          as: "user",
        },
      },
      { $unwind: "$user" },

      { $skip: options.page * options.limit },
      { $limit: options.limit },
      { $sort: { createdAt: 1 } },
    ]);
  } catch (error) {
    throw error;
  }
};

Answer 1

{ $match: { chatRoomId } } => { $match: { _id:chatRoomId } }

db.chatMessages.aggregate([
  {
    $match: { _id: 1 }
  },
  {
    $sort: { createdAt: -1 }
  },
  {
    $lookup: {
      from: "User",
      localField: "userId",
      foreignField: "_id",
      as: "user"
    }
  },
  {
    $unwind: "$user"
  },
  {
    $skip: 0
  },
  {
    $limit: 1
  },
  {
    $sort: { createdAt: 1 }
  }
])

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