在MongoDB中顯示來自另一個(gè)集合的數(shù)據(jù)

我在MongoDB中有兩個(gè)單獨(dú)的集合1->帖子，2->評(píng)論。

Post-schema:

const postSchema = new mongoose.Schema(
  {
    userId: {
      type: mongoose.Schema.Types.ObjectId,
      ref: "User",
      required: true,
    },
    media: {
      type: [mongoose.Schema.Types.Mixed],
      trim: true,
      required: true,
    },
    text: String,
    mentions: {
      type: Array,
      default: [],
    },
    hashTags: {
      type: ["String"],
    },
    likes: {
      type: Array,
      default: [],
    },
    postStatus: {
      type: "String",
      default: "public",
      enum: ["public", "private"],
    },
    deletedAt: {
      type: "Date",
      default: null,
    },
  },
  { timestamps: true }
);

comment schema:

const commentSchema = new mongoose.Schema(
  {
    userId: {
      type: mongoose.Schema.Types.ObjectId,
      ref: "User",
      required: true,
    },
    postId: {
      type: mongoose.Schema.Types.ObjectId,
      ref: "Post",
      required: true,
    },
    commentText: String,
  },
  { timestamps: true }
);

現(xiàn)在我想顯示請(qǐng)求帖子的所有評(píng)論。Post表沒有任何鏈接到注釋的內(nèi)容，這就是為什么我不能使用populate（）。但評(píng)論表已發(fā)布連接。

以下是我嘗試過的：

exports.getPostById = async (req, res) => {
  try {
    let post = await Post.findById(req.params.id);
    if (!post) return res.status(404).json({ message: "No Post found" });
    let comment = await Comment.find({ postId: { $in: {post: req.params.id} } });//Wrong query
    return res.status(200).send(post);
  } catch (error) {
    res.status(500).json({ message: error.message });
  }
};