如何根据另一个嵌套属性有条件地设置 TypeScript 属性？

Question

我有以下类型：

type Settings = {
    enableAdvancedFeature?: boolean;
};

type Options = {
    settings?: Settings;
    enforceAdvancedOrder?: boolean;
};

我想仅当

enforceAdvancedOrder

为

settings.enableAdvancedFeature

时才将

true

属性设置为布尔值。

如果

settings.enableAdvancedFeature

是

false

或

undefined

，那么

enforceAdvancedOrder

应该是

undefined

。

这是所需行为的示例：

const validOption1: Options = {
    settings: { enableAdvancedFeature: true },
    enforceAdvancedOrder: true,
};

const validOption2: Options = {
    settings: { enableAdvancedFeature: false },
    enforceAdvancedOrder: undefined, // enforceAdvancedOrder should be undefined
};

const invalidOption: Options = {
    settings: { enableAdvancedFeature: false },
    enforceAdvancedOrder: true, // This should cause a TypeScript error
};

我尝试为选项定义条件类型，但无法弄清楚如何在嵌套属性之间强制执行这种依赖关系。

如何定义选项类型来实现此行为，同时保持类型安全？任何建议将不胜感激！

Answer 1

就这样

type ConditionalOption =
    | { enforceAdvancedOrder?: boolean, settings?: { enableAdvancedFeature?: true } }
    | { enforceAdvancedOrder?: undefined, settings?: { enableAdvancedFeature?: false | undefined } }

示例

    let a: ConditionalOption = {
        settings: {
            enableAdvancedFeature: true
        },
        enforceAdvancedOrder: true
    } // okay
    let b: ConditionalOption = {
        settings: {
            enableAdvancedFeature: false
        },
        enforceAdvancedOrder: true,
    } // throws error
    let c: ConditionalOption = {
        settings: {
            enableAdvancedFeature: false
        },
        enforceAdvancedOrder: undefined
    } // okay