“ ITestData”可分配给“ IEntityData”类型的约束，但可以使用其他约束子类型实例化“ IEntityData”

问题描述

我有两节课。抽象超类：

export abstract class Entity<IEntityData> {
  protected readonly _source: IEntityData; // TODO: replace with private


  protected constructor(entityData: IEntityData) { this._source = entityData }

  get source(): IEntityData { return this._source }
}

和继承的类：

import { Entity } from './entity/entity';



interface ITestData {
  foo: string;
  bar: number;
}

export class Test<IEntityData extends ITestData = ITestData>
  extends Entity<IEntityData> {
  constructor(testData: ITestData) {
    super(testData);
  }

  get foo(): string { return this.source.foo }
  get bar(): number { return this.source.bar }
}

在构建期间出现错误。我不明白我在做什么错。

src/app/data/models/test.ts:13:11 - error TS2345: Argument of type 'ITestData' is not assignable to parameter of type 'IEntityData'.
      'ITestData' is assignable to the constraint of type 'IEntityData',but 'IEntityData' could be instantiated with a different subtype of constraint 'ITestData'.
    
    13     super(testData);

解决方法

哦，天哪！解决！我只是替换了这个：

constructor(testData: ITestData) {
  super(testData);
}

与此：

constructor(testData: IEntityData) {
  super(testData);
}