我正在尝试创造一个界面
export interface MenuItem {
title: string;
component?: any;
click?: any;
icon: string;
}
是否有方法要求组件或单击进行设置 是否有一种方法要求两个属性都不能设置?
我正在尝试创造一个界面
export interface MenuItem {
title: string;
component?: any;
click?: any;
icon: string;
}
是否有方法要求组件或单击进行设置 是否有一种方法要求两个属性都不能设置?
当前回答
我喜欢将Pick与包含所有属性的基本类型一起使用,以建立这些类型的条件需求。
interface MenuItemProps {
title: string;
component: any;
click: any;
icon: string;
}
export interface MenuItem =
Pick<MenuItemProps, "title" | "icon" | "component"> |
Pick<MenuItemProps, "title" | "icon" | "click">
这样既干净又灵活。您可以任意地复杂化您的需求,断言诸如“需要所有属性,只需要这两个属性,或者只需要这一个属性”之类的东西,同时保持您的声明简单易读。
其他回答
在TypeScript 2.8中添加的Exclude类型的帮助下,提供了一种要求至少一组属性中的一个的通用方法:
type RequireAtLeastOne<T, Keys extends keyof T = keyof T> =
Pick<T, Exclude<keyof T, Keys>>
& {
[K in Keys]-?: Required<Pick<T, K>> & Partial<Pick<T, Exclude<Keys, K>>>
}[Keys]
要求提供一个且仅提供一个的部分而非绝对的方法是:
type RequireOnlyOne<T, Keys extends keyof T = keyof T> =
Pick<T, Exclude<keyof T, Keys>>
& {
[K in Keys]-?:
Required<Pick<T, K>>
& Partial<Record<Exclude<Keys, K>, undefined>>
}[Keys]
下面是一个TypeScript游乐场链接,展示了两者的作用。
RequireOnlyOne的警告是TypeScript在编译时并不总是知道运行时存在的每个属性。因此,显然RequireOnlyOne不能做任何事情来防止它不知道的额外属性。我提供了一个示例,说明RequireOnlyOne如何错过playground链接末尾的内容。
使用以下示例快速概述它的工作原理:
interface MenuItem {
title: string;
component?: number;
click?: number;
icon: string;
}
type ClickOrComponent = RequireAtLeastOne<MenuItem, 'click' | 'component'>
Pick<T, Exclude<keyof T, Keys>> from RequireAtLeastOne becomes { title: string, icon: string}, which are the unchanged properties of the keys not included in 'click' | 'component' { [K in Keys]-?: Required<Pick<T, K>> & Partial<Pick<T, Exclude<Keys, K>>> }[Keys] from RequireAtLeastOne becomes { component: Required<{ component?: number }> & { click?: number }, click: Required<{ click?: number }> & { component?: number } }[Keys] Which becomes { component: { component: number, click?: number }, click: { click: number, component?: number } }['component' | 'click'] Which finally becomes {component: number, click?: number} | {click: number, component?: number} The intersection of steps 1 and 2 above { title: string, icon: string} & ({component: number, click?: number} | {click: number, component?: number}) simplifies to { title: string, icon: string, component: number, click?: number} | { title: string, icon: string, click: number, component?: number}
最后我这样做了:
export interface MenuItem {
title: string;
icon: string;
}
export interface MenuItemComponent extends MenuItem{
component: any;
}
export interface MenuItemClick extends MenuItem{
click: any;
}
然后我用了:
appMenuItems: Array<MenuItemComponent|MenuItemClick>;
但希望有一种方法可以用单一界面来建模。
我用这个:
type RequireField<T, K extends keyof T> = T & Required<Pick<T, K>>
用法:
let a : RequireField<TypeA, "fieldA" | "fieldB">;
这使得fieldA和fieldB是必需的。
这里有一个简单的方法来实现其中一个,但不是两个
type MenuItem = {
title: string;
component: any;
click?: never;
icon: string;
} | {
title: string;
component?: never;
click: any;
icon: string;
}
// good
const menuItemWithComponent: MenuItem = {
title: 'title',
component: "my component",
icon: "icon"
}
// good
const menuItemWithClick: MenuItem = {
title: 'title',
click: "my click",
icon: "icon"
}
// compile error
const menuItemWithBoth: MenuItem = {
title: 'title',
click: "my click",
component: "my click",
icon: "icon"
}
还有另一个解决方案:
type RequiredKeys<T, K extends keyof T> = Required<Pick<T, K>> & Omit<T, K>;
type MenuItem2 = RequiredKeys<MenuItem, "component" | "click">;