Question

这是我的代码，用于测试某些类对象的相等性。如果您想知道为什么我不只是在做，请参阅我的other question expect(receivedDeals).toEqual(expectedDeals)和其他更简单的断言。

   type DealCollection = { [key: number]: Deal };  // imported from another file

   it("does the whole saga thing", async () => {
      sagaStore.dispatch(startAction);
      await sagaStore.waitFor(successAction.type);
      const calledActionTypes: string[] = sagaStore
        .getCalledActions()
        .map(a => a.type);
      expect(calledActionTypes).toEqual([startAction.type, successAction.type]);
      const receivedDeals: DealCollection = sagaStore.getLatestCalledAction()
        .deals;
      Object.keys(receivedDeals).forEach((k: string) => {
        const id = Number(k);
        const deal = receivedDeals[id];
        const expected: Deal = expectedDeals[id];
        for (let key in expected) {
          if (typeof expected[key] === "function") continue;
          expect(expected[key]).toEqual(deal[key]);
        }
      });
    });

测试通过了，但是我在expected[key]上遇到了Flow错误：

Cannot get 'expected[key]' because an index signature declaring the expected key / value type is missing in 'Deal'

我可以根据请求从Deal粘贴代码，但是我想您需要知道的是我还没有声明索引签名（因为我不知道怎么做！）。

我搜索了一下，但找不到确切的情况。

更新：我可以通过这样更改deal和expected来消除错误：

const deal: Object = { ...receivedDeals[id] };
const expected: Object = { ...expectedDeals[id] };

由于我正在比较循环中的属性，所以这实际上不是问题。但是我认为我应该能够使用Deal来做到这一点，而且我想知道如何声明错误中提到的索引签名。

PS。额外的问题：在一个疯狂的科学家与Swift杂交JS的世界中，我想您可以做类似的事情

const deal: Object = { ...receivedDeals[id] where (typeof receivedDeals[id] !== "function" };
const expected = // same thing
expect(deal).toEqual(expected);

// And then after some recombining of objects:
expect(receivedDeals).toEqual(expectedDeals);

这是一回事吗？

编辑：

添加一些Deal类的定义：

Deal.js（摘要）

export default class Deal {
  obj: { [key: mixed]: mixed };
  id: number;
  name: string;
  slug: string;
  permalink: string;
  headline: string;
  // ...other property definitions

  constructor(obj?: Object) {
    if (!obj) return;
    this.id = obj.id;
    this.name = obj.name;
    this.headline = obj.headline;
    // ...etc
  }

  static fromApi(obj: Object): Deal {
    const deal = new Deal();
    deal.id = obj.id;
    deal.name = obj.name;
    deal.slug = obj.slug;
    deal.permalink = obj.permalink;
    // ...etc
    return deal;
  }

  descriptionWithTextSize(size: number): string {
    return this.descriptionWithStyle(`font-size:${size}`);
  }

  descriptionWithStyle(style: string): string {
    return `<div style="${style}">${this.description}</div>`;
  }

  distanceFromLocation = (
    location: Location,
    unit: unitOfDistance = "mi"
  ): number => {
    return distanceBetween(this.location, location);
  };

  distanceFrom = (otherDeal: Deal, unit: unitOfDistance = "mi"): number => {
    return distanceBetween(this.location, otherDeal.location);
  };

  static toApi(deal: Deal): Object {
    return { ...deal };
  }

  static collectionFromArray(array: Object[]) {
    const deals: DealCollection = {};
    array.forEach(p => (deals[p.id] = Deal.fromApi(p)));
    return deals;
  }
}

Answer 1

索引签名（或索引器属性）定义为[keyName: KeyType]: ValueType。 DealCollection是一个很好的例子：keyName是key，KeyType是number，而ValueType是Deal。这意味着每当您访问类型为DealCollection的对象的数字属性时，它将返回一个Deal。您将需要向Deal的定义添加类似的表达式，以便访问其上的任意属性。可以在Flow文档的Objects as maps部分中找到更多信息。

流程（InferError）：无法获取'object [key]'，因为在'Class'中缺少声明预期键/值类型的索引签名

编辑：

Deal.js（摘要）

1 个答案: