Custom validator on nested subdocument array field is not running on save()

[francescov1]

Do you want to request a feature or report a bug?

Report a bug

What is the current behavior?

When setting the field of a nested subdocument array, the field validator does not run when calling save(). This only happens when the document already exists in the DB and is being updated.

If the current behavior is a bug, please provide the steps to reproduce.

Note that the repro below requires a DB connection

import mongoose, { Schema } from 'mongoose';

const ChildSchema = new Schema(
  {
    price: {
      type: Number,
      validate: function (val: number) {
          return val > 0;
        }
    },
  }
);
const Child = mongoose.model('Child', ChildSchema);

const ParentSchema = new Schema(
  {
    // Note the nesting. If `nestedSubdocArray` is at the root level, the problem does not occur.
    rootField: {
      nestedSubdocArray: [Child.schema]
    }
  }
);
const Parent = mongoose.model('Parent', ParentSchema);

it('should throw if price is less than 0', async () => {
  const parentDoc = new Parent({
    rootField: {
      nestedSubdocArray: [
        {
          price: -1
        }
      ],
    }
  });

  // Throws error as expected (price must be greater than 0)
  await expect(parentDoc.save()).rejects.toThrow()
  
  // Now we set the price to a valid value and save
  parentDoc.rootField.nestedSubdocArray[0].price = 1;
  await parentDoc.save();

  // Now we try editing to an invalid value which should throw
  parentDoc.rootField.nestedSubdocArray[0].price = -1;
  // This test fails, the document saves successfully
  await expect(parentDoc.save()).rejects.toThrow()
})

What is the expected behavior?

Validation runs properly.

What are the versions of Node.js, Mongoose and MongoDB you are using? Note that "latest" is not a version.

Mongoose: 6.3.0
Node.js: 16.8
MongoDB: 5.0

Note that this started happening when I upgraded from Mongoose 6.1.6 to 6.3.0

[IslandRhythms]

const mongoose = require('mongoose');

const {Schema} = mongoose;

const childSchema = new Schema({
    price: { type: Number, validate: function (val) {
        return val > 0
    }}
});

const Child = mongoose.model('Child', childSchema);

const parentSchema = new Schema({
    rootField: {
        nestedSubdocArray: [Child.schema]
    }
});

const Parent = mongoose.model('Parent', parentSchema);

async function run() {
    await mongoose.connect('mongodb://localhost:27017');
    await mongoose.connection.dropDatabase();

    const doc = new Parent({
        rootField: {
            nestedSubdocArray: [{
                price: -1
            }]
        }
    });
    
    await doc.save().catch((err) => console.log(err));
    console.log('next');
    doc.rootField.nestedSubdocArray[0].price = 1;
    await doc.save();
    console.log('correct save complete');
    doc.rootField.nestedSubdocArray[0].price = -1;
    await doc.save();
    console.log('after incorrect save')
}

run();

[francescov1]

Is there a timeline on when this will be fixed? It's blocking us from upgrading Mongoose versions

[Uzlopak]

If you provide a PR it could be part of the next release :). But usually a ticket gets a milestone to it and it gets solved when there is capacity. I guess if you have a tidelift subscription, than @vkarpov15 would prioritize it as high and solve it asap.