Query all documents matching array of sub-documents

[vineetdigit]

My apologies since this question is not specific to mongoose, but MongoDB. But I have always found high-quality answers in this forum than elsewhere, hence asking it here.

I have a schema as follows

{
  postId: Number,
  threadId: Number,
  children: [ { postId: Number, threadId: Number } ]
}

I need to find all documents that match the fields of elements in the children array.

I know there is an $in operator but it works on only single field (e.g. postId). E.g. If children array was defined as [Number] where each element is a postId, then I could use

model.find({postId: {$in: doc.children})

[vkarpov15]

Maybe you're looking for $elemMatch? I'm not sure what "all documents that match the fields of elements in the children array" means, can you please provide an example?