Support square bracket notation for Document.prototype.set(): set('arr[0].path', val)

[gilles-yvetot]

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

What is the current behavior?
Cannot set a specific path

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

const mongoose = require('mongoose')
mongoose.set('debug', true)
const { Schema, model } = mongoose
const { Mixed } = Schema.Types

const VariableSchema = new Schema({
  type: String,
  valueType: String,
  value: Mixed,
  displayName: String,
  modifier: String,
})

const StepSchema = new Schema({ url: String }, { discriminatorKey: `type` })

const Step = model(`Step`, StepSchema)

const LoopConfigurationSchema = new Schema({
  loopItemsQueryPaths: [[VariableSchema]],
})
const LoopSchema = new Schema({
  configurations: {
    type: [LoopConfigurationSchema],
  },
})

Step.discriminator(`loop`, LoopSchema)

mongoose
  .connect('mongodb://localhost:27017/test', {
    useNewUrlParser: true,
    useUnifiedTopology: true,
  })
  .then(async () => {
    let doc = await Step.create({
      type: `loop`,
      configurations: [
        {
          loopItemsQueryPaths: [],
        },
      ],
    })

    doc.set({
      'configurations[0].loopItemsQueryPaths': [
        [
          {
            type: 'object',
            valueType: 'qbManualEntry',
            value: '//div',
          },
        ],
      ],
    })
    await doc.save()
    console.dir(doc.configurations[0].loopItemsQueryPaths) // print [] 
    process.exit()
  })
  .catch((err) => {
    console.error(err)
    process.exit(1)
  })

What is the expected behavior?

doc.configurations[0].loopItemsQueryPaths should be set, right now it is []
The gist is pretty big but I tried to make it as small as I could. I have re-read everything to make sure there was no typo too.
It looks similar to another issue I opened recently

What are the versions of Node.js, Mongoose and MongoDB you are using? Note that "latest" is not a version.
Node 6.13.2
Mongoose 6.2.7
Mongo 5.0.5

[vkarpov15]

I think the issue here is that we don't support square bracket syntax for set(). The below works:

    doc.set({
      'configurations.0.loopItemsQueryPaths': [
        [
          {
            type: 'object',
            valueType: 'qbManualEntry',
            value: '//div',
          },
        ],
      ],
    })

We'll take a look and see if this is something we can support

[vkarpov15]

We did some work to support this, including exporting stringToParts() from mpath, but it looks like this will be a more complex task than we thought because we need to support getting the schema path type of configurations[0].loopItemsQueryPaths in a couple of different cases. We'll postpone this to a future minor release.