打字稿:如何仅从类型中提取可选键? [英] Typescript: How to extract only the optional keys from a type?
本文介绍了打字稿:如何仅从类型中提取可选键?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
假设我有一个这样的类型:
Let's say I have a type like this:
type User = {
uid: string,
displayName?: string,
bestFriend?: string,
}
是否可以使用 a 从我的用户类型中提取可选属性某种映射类型?我正在寻找如何定义OptionalProperties
在下面输入.
Is it possible to extract the optional properties from my User type using a
mapped type of some kind? I'm looking for how to define the
OptioanlProperties<T>
type below.
type OptionalUserProperties = OptionalProperties<User>
// type OptionalUserProperties = "displayName" | "bestFriend"
我的用例是计算一个 UpdateOf
类型,它允许特定的操作"值,例如 DeleteProperty
分配给基本类型中可选的键.
My use-case is to compute an UpdateOf<User>
type that permits specific
"operation" values, like DeleteProperty
to be assigned to keys that are optional in the base type.
export type UpdateOf<T> =
// optional fields may be their own type, or the special DeleteProperty type.
{ [P in OptionalProperties<T>]?: T[P] | DeleteProperty } &
// required fields may be changed, but cannot be deleted.
{ [P in Diff<keyof T, OptionalProperties<T>>]?: T[P] }
推荐答案
是:
type OptionalPropertyOf<T extends object> = Exclude<{
[K in keyof T]: T extends Record<K, T[K]>
? never
: K
}[keyof T], undefined>
这篇关于打字稿:如何仅从类型中提取可选键?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文