Issue with export on JSON with disjunctions.

[conikeec]

Can disjunction be applied on two different types of schemas?

https://cuelang.org/play/?id=NDCY9W6wLsX#cue@export@json

What version of CUE are you using (cue version)?

$ cue version
cue version 0.4.0 darwin/amd64

What did you do?

//Platform details (if comprised of many products)
#Platform: {
    #Product,
    products: [...#Product]
}

//Product details
#Product: {
    id: int,
    name: string,
    oneLineDescription?: string,
    detailedDescription?: string
}

product: #Platform | #Product
product: { id : 10, name : "Product", oneLineDescription : "Great Product" }

What did you expect to see?

product: { id : 10, name : "Product", oneLineDescription : "Great Product" }

What did you see instead?

failed to encode: product: incomplete value {id:10,name:"Product",oneLineDescription:"Great Product",products:[]} | {id:10,name:"Product",oneLineDescription:"Great Product"}

[verdverm]

By embedding product in platform and then disjuncting them , you have created a subset situation. CUE cannot disambiguate a subset from the superset.

See #1163 for more details

[conikeec]

Thanks @verdverm

From a data modeling standpoint, a platform can be "many products" aggregated
In cases like these how can we leverage disjunction (product or platform)?

[verdverm]

Long-term: this is the comment to pay attention to: #1163 (reply in thread)

Short-term, you can use a discriminator field. Something that is in the data that can uniquely separate them, as I have used pid in this example: https://cuelang.org/play/?id=Oenn0KqbYqK#cue@export@cue

We could refine this depending on desired output and the data characteristics.

@myitcv should we convert this to a discussion?

[conikeec]

Thanks again @verdverm for the suggestion. I will try tonight.
Can I update the docs to reflect this use case with an example as I am suspecting this question might be asked again.

[verdverm]

You'd have to ask @myitcv that one.

I run https://cuetorials.com and would love to collab on the field subset problem/ example there. I have some thoughts already, if you open a discussion on the repo, we can iterate.

[conikeec]

@verdverm #1247

[mpvl]

The way to disambiguate in this case is to set a default value:

product: #Platform | *#Product

This picks the less specific version in case both succeed.

Much older versions of CUE were "smarter" and picked less specific cases over more specific cases. But this was a bit magical, aside from potential runtime inefficiencies, so we require explicit

I do think there is merit detecting subsumed and thus redundant values in disjunctions in a vet command.