Schema composition does not work

[gilles-yvetot]

Do you want to request a feature or report a bug?
bug
What is the current behavior?
Schema composition does not work
If the current behavior is a bug, please provide the steps to reproduce.

const { Schema, model } = require('mongoose')

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

const ClickSchema = new Schema(
  [
    StepSchema,
    {
      view: {
        clickCount: {
          type: Number,
          default: 1,
          min: 1,
        },
      },
    },
  ],
  { discriminatorKey: `type` },
)

const Step = model(`Step`, StepSchema)

Step.discriminator(`click`, ClickSchema)

const doc = new Step({
  type: `click`,
  view: { url: `https://google.com` },
})

console.log('doc.view.url', doc.view.url)

What is the expected behavior?
doc.view.url to be defined
What are the versions of Node.js, Mongoose and MongoDB you are using? Note that "latest" is not a version.
Node 12.13.0 (NOT the browser environment)
Mongoose: 5.10.1
MongoDB: 4.2.8

[vkarpov15]

The issue here is that view from the 2nd schema definition overrides the view from the first schema definition. We'll see if we can add an option to merge these instead.

[gilles-yvetot]

Okay, got it. I was expected paths to be merged. If you cannot add the option, let me know and I'll hack around 👍

[vkarpov15]

Turns out there was a bug with our fix for #9042 that caused this issue. Fix will be in v5.10.3, thanks for reporting 👍