TS errors for draft objects with properties that are indexed using well-known symbols

Aperta
  • Qualcosa non va?
#710 3 commenti 5 reazioni 0 assegnatari Vedi su GitHub

I maintainer di solito rispondono entro 4 giorni

Nessuno ha ancora preso questa issue.

Valutazione

Difficoltà
3/5
Tempo stimato
1-2 giorni
Idoneità per principianti
48/100
Tipo di issue
Bug
Chiarezza
Abbastanza chiara
Stato di attività
Ferma
Stack tecnologico
javascript, typescript
Ambito
developer-experience, tooling

Direzione di ricerca

Inizia individuando le definizioni dei tipi di Draft e WritableDraft e confronta il modo in cui gestiscono le proprietà dei simboli noti. Usa il repro TypeScript nell’issue per verificare sia l’accesso alle proprietà sia il passaggio di un draft a withFoo; il lavoro è completato quando il repro non produce errori TS senza modificare il comportamento di mutazione previsto.

Scritto dal modello di indicizzazione a partire dal testo della issue.

Descrizione

typescript

🐛 Bug Report

Draft<T> objects (at least according to TS) don't bring along any symbol-indexed properties from the original object. Is this expected? I'm not sure if this is only an issue in the TS types, or is the underlying JS draft object also missing its symbol-indexed properties?

Although well-known symbols are usually used with classes, I was able to repro the problem with a plain object too.

I'm using TS 4.1, if it matters.

FWIW, I ran into this because I was trying to call produce() with a deeply-nested object which had a Uint8Array-valued property far down in the tree. When I tried to pass the draft object to another method that expected the original type, TS complained that [Symbol.iterator] and [Symbol.toStringTag] properties that were required on Uint8Array but missing on the Draft<T> object. I'm not trying to mutate the array (that'd be #696); I'm just expecting a deep clone but (at least from TS's perspective) the symbol properties are missing.

Link to repro

import produce, { Draft } from 'immer';

const foo = {
  a() { return 42; },
  get [Symbol.toStringTag]() { return 'foo'; }
}

type Foo = typeof foo;

function withFoo(f: Foo) {
  return f[Symbol.toStringTag];
}

const ok = foo[Symbol.toStringTag];  // no error
const ok2 = withFoo(foo);  // no error

const producer = produce((draft: Draft<Foo>) => {
  draft.a();  // no error
  withFoo(draft);
  /*      ^^^^^
    Argument of type 'WritableDraft<{ a(): number; readonly [Symbol.toStringTag]: string; }>' 
    is not assignable to parameter of type '{ a(): number; readonly [Symbol.toStringTag]: string; }'.
    Property '[Symbol.toStringTag]' is missing in type 'WritableDraft<{ a(): number; 
    readonly [Symbol.toStringTag]: string; }>' but required in type 
    '{ a(): number; readonly [Symbol.toStringTag]: string; }'. (2345)
  */

  const fail = draft[Symbol.toStringTag];
  /*           ^^^^^^^^^^^^^^^^^^^^^^^^^
     Element implicitly has an 'any' type because expression of type 'symbol' can't be used
     to index type 'WritableDraft<{ a(): number; readonly [Symbol.toStringTag]: string; }>'.(7053)
  */
});

https://www.typescriptlang.org/play?#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-LaGK4nQAFJCpWCGhhpzZjPMW4IOl1wEAur1+Z1aMWMKX1P0K2nK2Sxs7xqAGJ06vV8A1G4Y1s1Z-a5m2Ge1wByoeCqACOqGAqmQHZyUcdrIYMYUcccCcnKdnJozdezy92BdccDkugAzNoAKwKExGSObgZD+BYyBIYBnGyXEKGrU1M0mfYuBkJlWXQmROSw7CcNwp04AAUXlIV4FAMBnGAdB6hnBoPVkLQGBIPhbAdLtNXQEhUAENJMAAD0QTBPSqLR8mPVJGAEOdnAdDi+AYeBNTgLjMGQfCPA7ZA+LE8UexlOV+0RQdVRHa8x0TZNp1TY101rc1nzga1X1XQs5AAdgABl-L8AJkICEnpIA

LMK if you want me to turn the TS playground code above into a CodeSandbox example; happy to do so.

To Reproduce

Steps to reproduce the behavior:

  1. Create a producer that accepts a TS type that has a well-known symbol property
  2. Try to read that property or call a function that accepts a parameter of T from Draft<T>. Note that mutation is not required-- this problem affects read-only access.

Observed behavior

TS errors as noted above.

Expected behavior

No TS errors.

Environment

We only accept bug reports against the latest Immer version.

  • Immer version:
  • I filed this report against the latest version of Immer
  • [n/a (TS only)] Occurs with setUseProxies(true)
  • [n/a (TS only)] Occurs with setUseProxies(false) (ES5 only)
Lingua principale
JavaScript
Stelle
29k
Fork
905
Merge medio
3g 16h
PR unite (30g)
22

Preparare l'ambiente

Questo progetto non fornisce container di sviluppo, Dockerfile né guida per i contributori, quindi l'ambiente è a tuo carico: parti dal suo README e consulta la nostra guida al primo contributo per i passaggi generali.

Come iniziare

  1. Leggi tutta la issue e poi la guida ai contributi del progetto.
  2. Commenta sulla issue per dire che te ne occupi tu — evita che due persone facciano lo stesso lavoro.
  3. Fai un fork del repository e lavora su un branch.
  4. Apri una pull request che faccia riferimento al numero della issue.

Altre issue di immerjs/immer

Tutte le issue di immerjs/immer

Issue simili

Altre issue su JavaScript

Ricevi le nuove issue nella tua casella

Un breve riepilogo di issue GitHub adatte ai principianti.