Typescript: 如何包装接口属性？

huangapple
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英文:

Typescript: How to wrap interface properties?

问题

  1. 假设我有以下的定义：
  3. ```js
  4. interface ISomeInterface {
  5.   propertyA: string,
  6.   propertyB: number,
  7.   propertyC: boolean,
  8.   propertyD: ISomeOtherInterface // bonus points for this one!
  9. }
  11. class MyGeneric<T> {}
  12. class MyGenericContainer<T> {}

现在我想要"包装"所有属性，使得我得到类似这样的结果：

  1. interface ISomeWrappedInterface {
  2.   propertyA: MyGeneric<string>,
  3.   propertyB: MyGeneric<number>,
  4.   propertyC: MyGeneric<boolean>,
  5.   propertyD: MyGenericContainer<ISomeOtherInterface>
  6. }

注意：propertyD 可能是不可能的，但如果属性类型不是某种"基本"类型，我只是希望它被另一个类包装

这是我已经完成的部分：

  1. type FromInterface<I> = ({
  2.   [T in keyof I]: MyGeneric<typeof T>;
  3.                                    ^--------
  4. });
  6. type Wrapped = FromInterface<ISomeInterface>;

但这不起作用，因为'T' only refers to a type, but is being used as a value here。我猜这是因为T在这里已经是一个类型，但显然我想要迭代的属性的"type"类型。

免责声明：我找到了这个问题，看起来类似，但实际上不是。

  2. <details>
  3. <summary>英文:</summary>
  5. Suppose I have the following definitions:
  7. ```js
  8. interface ISomeInterface {
  9.   propertyA: string,
  10.   propertyB: number,
  11.   propertyC: boolean,
  12.   propertyD: ISomeOtherInterface // bonus points for this one!
  13. }
  15. class MyGeneric&lt;T&gt; {}
  16. class MyGenericContainer&lt;T&gt; {}

now I want to "wrap" all properties, so that I recieve something like that:

  1. interface ISomeWrappedInterface {
  2.   propertyA: MyGeneric&lt;string&gt;,
  3.   propertyB: MyGeneric&lt;number&gt;,
  4.   propertyC: MyGeneric&lt;boolean&gt;,
  5.   propertyD: MyGenericContainer&lt;ISomeOtherInterface&gt;
  6. }

Note: PropertyD is probably impossible, but in case the property type is not some "primitive", I simply want it to be wrapped by another class

This is as far as I have gotten:

  1. type FromInterface&lt;I&gt; = ({
  2.   [T in keyof I]: MyGeneric&lt;typeof T&gt;;
  3.                                    ^--------
  4. });
  6. type Wrapped = FromInterface&lt;ISomeInterface&gt;;

But this does not work, because &#39;T&#39; only refers to a type, but is being used as a value here.
I guess it's because T already is a type here, but obviously I want the "widened" type of the property that I am iterating.

Disclaimer: I've found this question, seems similar, but isn't.

答案1

得分: 1

你可以使用以下方法：

  1. type FromInterface<T> = {
  2.   [K in keyof T]: T[K] extends string | number | Date
  3.     ? MyGeneric<T[K]>
  4.     : MyGenericContainer<T[K]>;
  5. };

Playground链接

英文:

You can use:

  • mapped type to transform each proprerty in the input type
  • conditional type to select output property type depending on some condition
  1. type FromInterface&lt;T&gt; = {
  2.   [K in keyof T]: T[K] extends string | number | Date 
  3.                   ? MyGeneric&lt;T[K]&gt; 
  4.                   : MyGenericContainer&lt;T[K]&gt;;                            
  5. };

Playground link

huangapple
  • 本文由 发表于 2023年3月4日 02:28:53
  • 转载请务必保留本文链接：https://go.coder-hub.com/75630665.html
  • typescript
  • typescript-generics
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