I have the following schema (NestJS Mongoose):

@Schema({ timestamps: true })
export class Listing {
  @Prop({
        type: [{
            bidderId: { type: Types.ObjectId, required: true, select: false, ref: User.name, index: true },
            amount: { type: Number, required: true },
            date: { type: Date, required: true }
        }],
        select: false
    })
        bids!: Bid[]
}

so basically every listing document has an array of bids.
now I notice that automatically mongoDB (or mongoose) creates _id field for every bid item I put into the bids array.

My question is, If I have a bid's _id, how can I query it's item from the listing's bids array? something like:

  // Adding a new bid to the listing, and retrieving the updated listing
  const listingWithAddedBid = await this.listingModel.findByIdAndUpdate(listingId, {
    $push: {
        bids: {
            $each: [{
                amount: bidInfo.amount,
                bidderId: new Types.ObjectId(user.id),
                date: new Date()
            }],
            $sort: { amount: -1 }
        }
    }
}, { new: true })

  // Getting the new bid's _id from the array (it will be at index 0 because we sort buy amount)
  const newBidId = listingWithAddedBid.bids[0]._id

  // here how can I query the entire bid item from the array with 'newBidId'? this won't work
  this.listingModel.findById(newBidId) // returns null

CodePudding user response：

https://docs.mongodb.com/manual/tutorial/query-array-of-documents/ https://docs.mongodb.com/manual/indexes/#default-_id-index

this.listingModel.findOne({ "bids._id": newBidId, {}, {}, (error, doc) =>
        {
         if (error) {
                ....
              }
              if (doc) {
                ....
              } else {
                ...//'Not Found';
              }
        });