Typescript泛型中对接口成员的约束 [英] Constraints on interface members in typescript generics

问题描述

我有一个方法，只要它的所有字段都是字符串或数字，它就可以接受任何对象

I have a method, that should accepts any object, as long as all its fields are strings or numbers

我做到了这一点，它与鸭子输入非常有用

I made this, which works great with duck typing

static interpolateParams(
    route: string, 
    params: {[key: string] : string | number}) : string {

    const parts = route
        .split("/")
        .map(part => {
            const match = part.match(/:([a-zA-Z09]*)\??/);
            if (match) {
                if (!params[match[1]]) {
                    console.error("route argument was not provided", route, match[1]);
                    return part;
                }

                return params[match[1]];
            }
            else {
                return part;
            }
        })

    return "/" + parts.slice(1).join("/");
}

并致电

interpolateParams("/api/:method/:value", {method: "abc", value: 10});

现在我想让 interpolateParams 接受路由 params 的任何接口。

Now I want to make interpolateParams to accept any interface for route params.

interpolateParams<IABCParams>("/api/:method/:value", {method: "abc", value: 10});

问题是，对于所有字符串或数字字段，它仍然应该匹配约束

是否可以在给定接口的所有字段上将通用约束指定为特定类型？

Is there a way to specify generic constraint on all fields of given interface to be of certain type?

我尝试过

static interpolateParams<T extends {[key: string] : string | number}>(
    route: string, 
    params: T) : string {

显然得到了这个

类型'IABCParams'不满足约束'{{key：string]：string |数; }'。

Type 'IABCParams' does not satisfy the constraint '{ [key: string]: string | number; }'.

'IABCParams'类型缺少索引签名。

Index signature is missing in type 'IABCParams'.

谢谢

推荐答案

T 的约束可以引用 T （有一些限制），因此您可以使用映射类型来生成约束，该约束具有与 T 相同的字段：

T's constraint can refer to T (with some restrictions), so you can use a mapped type to generate a constraint that has the same fields as T:

function interpolateParams<T extends {[P in keyof T] : string | number}>(
    route: string, 
    params: T) : string { /*...*/ }

请注意，使用圆形类型参数约束的欺骗有时可能会导致问题，尽管这种情况很可能会解决。

Beware that trickery with circular type parameter constraints can sometimes cause problems, though this scenario will likely be OK.

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