combineLatest 和严格类型错误 - "No overload matches this call."

Question

最近将项目从 Angular v9 更新到 v11。选择了严格的打字，当然得到了无数的错误，难倒了这个。

使用 combineLatest 从 3 个 observables 生成一个发布（每个都是一个 firebase doc.valueChanges() 或 collection.valueChanges()）

我的代码：

getEdition(editionId: string): AngularFirestoreDocument<Edition> {
    return this.afs.collection('editions').doc(editionId);
}

const editionRef: Observable<Edition | undefined> = this.editionService.getEdition(ed.id).valueChanges();

combineLatest([editionRef, sectionsRef, articlesRef]).subscribe(([edition, sections, articles]: [Edition, Section[], Article[]]) => {
   // do stuff, returns void
});

Edition.ts:

import { Moment } from 'moment';

export interface Edition {
  id: string;
  pubTypeId: string;
  date: string | Moment;
  imgCaption: string;
  imgCredit: string;
  imgLink: string;
  imgSrc: string;
  introText: string;
  hasPreface: boolean;
  preface: string;
  printLink: string;
}

我的错误：

error TS2769: No overload matches this call.
  Overload 1 of 5, '(observer?: NextObserver<[Edition | undefined, DocumentData, DocumentData]> | ErrorObserver<[Edition | undefined, DocumentData, DocumentData]> | CompletionObserver<...> | undefined): Subscription', gave the following error.
    Argument of type '([edition, sections, articles]: [Edition, Section[], Article[]]) => void' is not assignable to parameter of type 'NextObserver<[Edition | undefined, DocumentData, DocumentData]> | ErrorObserver<[Edition | undefined, DocumentData, D
ocumentData]> | CompletionObserver<...> | undefined'.
      Property 'complete' is missing in type '([edition, sections, articles]: [Edition, Section[], Article[]]) => void' but required in type 'CompletionObserver<[Edition | undefined, DocumentData, DocumentData]>'.
  Overload 2 of 5, '(next?: ((value: [Edition | undefined, DocumentData, DocumentData]) => void) | undefined, error?: ((error: any) => void) | undefined, complete?: (() => void) | undefined): Subscription', gave the following error.
    Argument of type '([edition, sections, articles]: [Edition, Section[], Article[]]) => void' is not assignable to parameter of type '(value: [Edition | undefined, DocumentData, DocumentData]) => void'.
      Types of parameters '__0' and 'value' are incompatible.
        Type '[Edition | undefined, DocumentData, DocumentData]' is not assignable to type '[Edition, Section[], Article[]]'.
          Type 'Edition | undefined' is not assignable to type 'Edition'.
            Type 'undefined' is not assignable to type 'Edition'.

我知道我需要以某种方式调整我的打字，但鉴于我在这里使用的是 combineLatest，我不确定该怎么做...

Answer 1

我的猜测是 editionRef -> edition -> Edition 链中的某处有一个隐含的 any 类型。来自文档：

Any variable, parameter or property that is initialized with null or undefined will have type any, even if strict null checks is turned on.

所以我会首先尝试在该链中找到一个未初始化的 undefined 或 null 变量。

错误

Type 'undefined' is not assignable to type 'Edition'.

表示 this.editionService.getEdition(ed.id).valueChanges() 永远不允许 return undefined 并且 Observable 的类型只能是 Edition.

最后，在您的修复中，最好实际指明需要强制执行的类型。

您可以我们 as 对类型进行类型转换，但您正在将您不确定的内容更改为您需要的内容。此选项可能会起作用，但不会按照输入的方式“强制”输入。

所以最好的解决方案，正如您在评论中所说：

subscribe(([edition, sections, articles]: [Edition | undefined, Section[], Article[]]) => { ... }

combineLatest 和严格类型错误 - "No overload matches this call."

Error with combineLatest and strict typings - "No overload matches this call."

typescript

angularfire2

angular