在Mongoose中使用填充虚拟机时如何聚合? [英] How to aggregate when using populate virtuals in Mongoose?

问题描述

我正在尝试使用猫鼬的填充虚拟机.假设我有以下Post模式:

I'm trying to use mongoose's populate virtuals. Let's say I have this Post schema:

const postSchema = new mongoose.Schema({
  title: {
    type: String,
    required: true
  },
  content: {
    type: String,
    required: true
  }
});
postSchema.virtual('comments', {
  ref: 'Comment',
  foreignField: '_id',
  localField: 'post'
});

现在，假设我想使用aggregate按评论内容进行过滤:

Now, let's say I wanted to filter by the comment content using aggregate:

Post.aggregate([
  {
    $match: {
      $or: [{ 'comments.content': /match this content/ }]
    }
  },
  {
    $project: { title: 1, comments: 1 }
  }
)]

这不起作用，因为尚未填充comments.有其他选择吗?

This doesn't work because comments hasn't been populated. Any alternatives?

推荐答案

我认为您可以这样做:

Post.aggregate([
  {
    $lookup:{
      from:"comments",
      localField:"_id",
      foreignField:"post",
      as:"comments"
    },
    $unwind:{
      "$comments"
    },
    $match: {
      $or: [{ 'comments.content': /match this content/ }]
    }
  },
  {
    $project: { title: 1, comments: 1 }
  }
)]`

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