您可以使用现有的解决方案,例如typescript-is https://www.npmjs.com/package/typescript-is,尽管这可能需要您切换到ttypescript
(允许插件的编译器的自定义构建)
如果您需要自定义解决方案,我们可以使用纯 TS 构建一个解决方案。首先是要求:
最后一个要求可以通过拥有一个具有相同键的对象来满足A
,所有必需的键和值是属性的类型。这样一个对象的类型是Record<keyof A, Types>
。然后这个对象可以用作验证的源,我们可以获取每个键并验证它的指定类型:
interface A {
a: string
}
type Types = "string" | "number" | "boolean";
function asA(data: unknown): A {
const keyValidators: Record<keyof A, Types> = {
a: "string"
}
if (typeof data === 'object' && data !== null) {
let maybeA = data as A
for (const key of Object.keys(keyValidators) as Array<keyof A>) {
if (typeof maybeA[key] !== keyValidators[key]) {
throw new Error('data is not an A');
}
}
return maybeA;
}
throw new Error('data is not an A');
}
let data: unknown = JSON.parse('{"a": "yes"}');
let a = asA(data);
我们可以更进一步,创建一个可以验证任何对象类型的通用工厂函数,我们还可以允许一些额外的事情,例如指定函数或允许可选属性:
interface A {
a: string
opt?: string
// b: number // error if you add b
}
function asOptional<T>(as: (s: unknown, errMsg?: string) => T) {
return function (s: unknown, errMsg?: string): T | undefined {
if (s === undefined) return s;
return as(s);
}
}
function asString(s: unknown, errMsg: string = ""): string {
if (typeof s === "string") return s as string
throw new Error(`${errMsg} '${s} is not a string`)
}
function asNumber(s: unknown, errMsg?: string): number {
if (typeof s === "number") return s as number;
throw new Error(`${errMsg} '${s} is not a string`)
}
type KeyValidators<T> = {
[P in keyof T]-?: (s: unknown, errMsg?: string) => T[P]
}
function asFactory<T extends object>(keyValidators:KeyValidators<T>) {
return function (data: unknown, errMsg: string = ""): T {
console.log(data);
if (typeof data === 'object' && data !== null) {
let maybeT = data as T
for (const key of Object.keys(keyValidators) as Array<keyof T>) {
keyValidators[key](maybeT[key], errMsg + key + ":");
}
return maybeT;
}
throw new Error(errMsg + 'data is not an A');
}
}
let data: unknown = JSON.parse('{"a": "yes"}');
const asA = asFactory<A>({
a: asString,
opt: asOptional(asString)
/// b: asNumber
})
let a = asA(data);
interface B {
a: A
}
const asB = asFactory<B>({
a: asA
})
let data2: unknown = JSON.parse('{ "a": {"a": "yes"} }');
let b = asB(data2);
let berr = asB(data);