Allow consumer to further alter the behavior of isDraftable

[thesnups]

🚀 Feature Proposal

I'm not 100% sure what this API would look like, but I'd like to see the mechanism for altering the behavior of isDraftable to be more configurable by the consumer. The current mechanism (applying the immerable symbol to objects that would otherwise be undraftable) is limiting for my use case.

Motivation

In my app there are two window contexts (the top window and an iframe window context) in which objects are created, and these objects frequently get passed between the two contexts. Immer's current isDraftable predicate only returns true for objects that are created in the same window context as itself, which means it only returns true for objects that were created in the top window. The immerable symbol could be used to solve this problem, but we would need to apply it in many places, whereas it would be simpler to have a way to tell Immer to take into account objects from either window context.

Example

Again, I'm not sure what it should look like, but one idea would be to allow the consumer to specify it's own isDraftable predicate that either A) overrides the built-in isDraftable, or B) is used as a "final" check when all of the existing isDraftable checks fail.

import { setIsDraftableOverride } from 'immer';

function myCustomIsDraftableFunction(val) {
  // ...
}

setIsDraftableOverride(myCustomIsDraftableFunction);

Let me know your thoughts!

[mweststrate]

I think that might be fixed if you would also share immer between the windows?

[thesnups]

How do you propose doing this? I'm not seeing how that could work. The problem is on this line: https://github.com/immerjs/immer/blob/master/src/common.js#L31 Immer only checks for objects created with the object prototype in its current scope. Not objects created in other windows

[mweststrate]

I think a solution could be to add the symbol to check for as argument to the `Immer` constructor, which is consistent with other not-common customizations of immer.

…

On Sat, Sep 28, 2019 at 3:04 AM Daniel Worsnup ***@***.***> wrote: How do you propose doing this? I'm not seeing how that could work. The problem is on this line: https://github.com/immerjs/immer/blob/master/src/common.js#L31 Immer only checks for objects created with the object prototype in its current scope. Not objects created in other windows — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#405?email_source=notifications&email_token=AAN4NBBMKSACLWPQG2VSZO3QL23SJA5CNFSM4ILDNOJKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD72OJJI#issuecomment-536143013>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAN4NBCIJMH7QX6NSHHJM5TQL23SJANCNFSM4ILDNOJA> .

[mweststrate]

For the object check: this check (from redux toolkit) might work cross frames?

function isPlainObject(value) {
  if (typeof value !== 'object' || value === null) return false;
  var proto = value;

  while (Object.getPrototypeOf(proto) !== null) {
    proto = Object.getPrototypeOf(proto);
  }

  return Object.getPrototypeOf(value) === proto;
}

[mweststrate]

Closing for inactivity

[atvoid]

@mweststrate I think the one from lodash is better. what do you think ?

export function isPlainObject(value: any): boolean {
	if (!value || typeof value !== "object") return false
	const proto = Object.getPrototypeOf(value)
	if (proto === null) {
		return true
	}
	const Ctor =
		Object.hasOwnProperty.call(proto, "constructor") && proto.constructor
	return (
		typeof Ctor == "function" &&
		Function.toString.call(Ctor) === objectCtorString
	)
}

#767