Unable to morph process.env values to non-strings

[TizzySaurus]

Report a bug

🔎 Search Terms

pipe, object, process.env

🧩 Context

• ArkType version: 2.0-dev.26
• TypeScript version (5.1+): 5.5
• Other context you think may be relevant (JS flavor, OS, etc.): N/A

🧑‍💻 Repro

import { type } from "arktype"

process.env.VALUE = "true"

const t = type({
    VALUE: ["'true'|'false'", "=>", x => {console.log("hi from morph"); return x === "true"}]
})
const envs1 = t.assert(process.env) // runs morph but doesn't change `VALUE` to boolean
console.log(typeof envs1.VALUE) // string

const envs2 = t.assert(Object.fromEntries(Object.entries(process.env))) // runs morph and changes `VALUE` to boolean
console.log(typeof envs2.VALUE) // boolean

[TizzySaurus]

After further investigation with @dikatok on Discord, it seems the cause of this is actually that process.env is an "exotic object" (i.e. "not a standard object"), for which in this case it's impossible to have a non-string value (values get coerced to string):

More info about this process.env functionality is detailed within nodejs/node#12126.

It would be nice if ArkType could somehow detect this, and automatically convert to a standard object via the spread operator ({...process.env, keyBeingMorphed: resultOfMorph}). The following changes to this code seem to do the trick, but I've not thoroughly tested:

				// apply the morph function and assign the result to the
				// corresponding property, or to root if path is empty
				if (parent === undefined) this.root = result
				else parent[key!] = result

                                /* Changes are all below */
				// `process.env` doesn't allow non-string values,
				// so we have to create a copy object.
                                // https://github.com/nodejs/node/issues/12126
				if (typeof result !== "string" && typeof parent[key!] === "string")
					parent = {...parent, key: result}

[Dimava]

This should be a clone-morph, do we have those?

I'm not sure if AT should have exceptions for exotic objects (process.env, localStorage, Proxy instances)

[dikatok]

@Dimava the best workaround for those kind of objects is cloning by ourselves on application level before feeding it to AT? at least for the moment?

[ssalbdivad]

@dikatok Yes. I do plan eventually to offer a config option to clone before morphing:

#959

For now, just spread process .env before applying your morph