FieldByName Can't Get Hidden Field

[rawkode]

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

0.3.0

Does this issue reproduce with the latest release?

FieldByName has a second parameter, a bool; which according to the comments should allow us to get a hidden field or definition.

package main

import (
	"fmt"

	"cuelang.org/go/cue"
)

func main() {
	var cueRuntime cue.Runtime

	testCue := `{
	_schema: {
		version: "v1"
	}
}`

	cueInstance, err := cueRuntime.Compile("", testCue)
	cueValue := cueInstance.Value()

	hiddenField, err := cueValue.FieldByName("_schema", true)
	if err != nil {
		fmt.Println("Error", err)
	}
	fmt.Println(hiddenField.Name)

	fields, _ := cueValue.Fields(cue.All())
	for fields.Next() {
		if fields.Label() == "_schema" {
			fmt.Println("Found _schema", fields.Value())
		}
	}
}

[mpvl]

We have just officially deprecated FieldByName. Hidden fields are tricky, as they are scoped by package, pretty much like Go's non-exported names. So FieldByName was broken for that purpose.

Really the only thing you'll need for looking up fields is LookupPath.

E.g. v.LookupPath(cue.MakePath(cue.Hid("_schema", "_"))).

This API will allow looking up hidden fields related to any of the packages.

[mpvl]

Note that the Iterator interface is broken too in that regard. We should implement Selector, instead of Label, to be accurate.

The API is currently being reworked to use the Path/Selector approach, which is nice, much more powerful, and prepares for the CUE query extension (#165 ).

[cueckoo]

This issue has been migrated to cue-lang/cue#880.

For more details about CUE's migration to a new home, please see cue-lang/cue#1078.