[英]How to create a Typescript type based on the keys/values of a dictionary?
有没有办法根据字典值自动生成类型? 例如,给定这个常量值字典:
export const SHIPMETHODS: OptionsMap<UpsShipMethodOption> = {
'UPS': 'GND',
'UPS AIR2': '2DA',
'UPS 3DAY SELECT': '3DS'
}
有没有办法自动生成这样的类型,而不必复制所有内容?
export type ShipMethodOptionMap = {
'UPS': 'GND',
'UPS AIR2': '2DA',
'UPS 3DAY SELECT': '3DS'
}
不幸的是 keyof 似乎不起作用,因为它是 object 而不是类型,所以这不起作用:
export type UpsShipMethodOption = keyof SHIPMETHODS // Doesn't work
我还尝试将映射类型与键的预声明联合类型一起使用,但它也不起作用:
/*
Type 'KeyOptions' is not assignable to type 'string | number | symbol'.
Type 'KeyOptions' is not assignable to type 'symbol'.ts(2322)
*/
export type OptionsMap<KeyOptions> = {
readonly [Property in KeyOptions]: string;
}
export const SHIPMETHODS: OptionsMap<UpsShipMethodOption> = {
'UPS': 'GND',
'UPS AIR2': '2DA',
'UPS 3DAY SELECT': '3DS'
}
export type UpsShipMethodOption = 'UPS' | 'UPS AIR2' | 'UPS 3DAY SELECT'
我有一堆这样的词典,其中大部分都很大(30+键)。 将字典复制到任何地方都会使维护起来很痛苦,以防值发生变化,所以任何帮助都会很棒!
我认为您只需要typeof
运算符。 它只是获取值的类型。
const SHIPMETHODS = {
'UPS': 'GND',
'UPS AIR2': '2DA',
'UPS 3DAY SELECT': '3DS'
} as const // as const is important.
type ShipMethodOptionMap = typeof SHIPMETHODS
/*
type ShipMethodOptionMap = {
readonly UPS: "GND";
readonly 'UPS AIR2': "2DA";
readonly 'UPS 3DAY SELECT': "3DS";
}
*/
type UpsShipMethodOption = keyof ShipMethodOptionMap
// type UpsShipMethodOption = "UPS" | "UPS AIR2" | "UPS 3DAY SELECT"
只需注意object 上的as const
,它允许 typescript 推断字符串文字,以便它们成为类型的一部分。
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