I have the following schema for a grid (evaluation grid). Grid => Sections => Criteria => Levels and I want to update a single Level element.

const mongoose = require("mongoose");

const levelSchema = mongoose.Schema(
  {
    title: {
      type: String,
      required: true,
    },
    value: {
      type: Number,
      required: true,
    },
  },
  { timestamps: true }
);

exports.Level = mongoose.model("Level", levelSchema);

const criterionSchema = mongoose.Schema(
  {
    title: {
      type: String,
      required: true,
    },
    levels: [levelSchema],
  },
  { timestamps: true }
);

criterionSchema.virtual("weight").get(function () {
  return Math.max(this.levels.map((level) => level.weigth));
});

exports.Criterion = mongoose.model("Criterion", criterionSchema);

const sectionSchema = mongoose.Schema(
  {
    name: {
      type: String,
      required: true,
    },
    criteria: [criterionSchema],
  },
  { timestamps: true }
);

sectionSchema.virtual("weight").get(function () {
  return this.criteria.reduce((acc, criteria) => acc + criteria.weight, 0);
});

exports.Section = mongoose.model("Section", sectionSchema);

const schema = mongoose.Schema(
  {
    name: {
      type: String,
      required: true,
    },

    sections: [sectionSchema],
    code: { type: Number, required: true },
    course: {
      type: mongoose.Schema.Types.ObjectId,
      ref: "Course",
      required: true,
    },
  },
  { timestamps: true }
);
schema.virtual("weight").get(function () {
  return this.sections.reduce((acc, section) => acc + section.weight, 0);
});

exports.Grid = mongoose.model("Grid", schema);

I was able to retrieve a specific Level's Grid with this code :

Grid.findOne({"sections.criteria.levels._id": levelId})

So I tried FindOneAndUpdate with this code :

const grid = await Grid.findOneAndUpdate(
      { "sections.criteria.levels._id": req.params.levelId },
      {
        $set: {
          "sections.$[].criteria.$[].levels.$[].title": req.body.title,
        },
      },
      { new: true });

But, it changed ALL the Levels of the grid.

How can we update a single Level sub, sub, sub document and returns it ?