我们有一个基础StoreObject
类,它为保存到数据库的对象提供了转换/消毒等通用方法。我希望能够使用泛型从这些方法中指定更严格的返回类型。但是,在将typeof StoreObject
与typeof AClassThatExtendsStoreObject
进行比较时,我的尝试导致了错误,这是我们在各种实用程序功能中所做的检查。您能指出我在下面做错了什么的方向吗?
class StoreObject<S> {
toStoreObject(s: S): S {
// Perform some sanitisation etc.
return s;
}
}
interface Fact {
id: string;
fact: string;
}
// A concrete implementation of StoreUnit where we attempt to define the actual model of the object being stored
class FactStoreObject extends StoreObject<Fact> {}
// We've got some general utils that interact objects using these classes
// These typicallay take a concrete implementation of StoreUnit to be used as a parser/processer
function doSomething(StoreObjectClass: typeof StoreObject) {
// Typically:
// const parsedObject = new StoreObjectClass(someObject).toStoreObject()
// persistToDb(parsedObject)
}
// This errors with "Type 'S' is not assignable to type 'Fact'"
doSomething(FactStoreObject);
答案 0 :(得分:1)
由于此行而导致错误:
const parsedObject = new StoreObjectClass(someObject)
首先,您需要可构造的接口:
export interface IConstructable<T> {
new (): T;
}
第二,您需要在工厂方法中包括该类型的参数:
function doSomething<T>( t: IConstructable<T> ) {
const parsedObject = ( new t() ).toStoreObject();
// persistToDb(parsedObject);
}
答案 1 :(得分:0)
在提供的代码中,在“ doSomething”函数中,参数类型被指定为“ StoreObject”,而没有指定其泛型类型。为了解决该错误,您需要执行以下操作:
这是示例:
function doSomething<T>(StoreObjectClass: { new(): StoreObject<T> }) {
// typically
const someObject = <any>{id: "001", fact: "A real fact"};
const parsedObject = new StoreObjectClass().toStoreObject(someObject);
// persistToDb(parsedObject)
}
doSomething<Fact>(FactStoreObject);