在TypeScript中扩展React组件

我正在使用React.js和TypeScript . 有没有办法创建从其他组件继承但有一些额外的道具/状态的React组件?

我想要实现的是这样的:

interface BaseStates {
    a: number;
}

class GenericBase<S extends BaseStates> extends React.Component<void, S> {
    protected getBaseInitialState(): BaseStates {
        return { a: 3 };
    }
}

class Base extends GenericBase<BaseStates> {
    getInitialState(): BaseStates {
        return super.getBaseInitialState();
    }
}

interface DerivedStates extends BaseStates {
    b: number;
}

class Derived extends GenericBase<DerivedStates> {
    getInitialState(): DerivedStates {
        var initialStates = super.getBaseInitialState() as DerivedStates; // unsafe??
        initialStates.b = 4;
        return initialStates
    }
}

但是,如果我在 Derived 中调用 this.setState ,则会失败,我收到TypeScript错误( DerivedStates 类型的参数不能分配给 S 类型) . 我想这不是特定于TypeScript的东西,而是将继承与泛型混合的一般限制(?) . 这有什么类型安全的解决方法吗?

UPDATE

我解决的解决方案(根据David Sherret的回答):

interface BaseStates {
    a: number;
}

class GenericBase<S extends BaseStates> extends React.Component<void, S> {
    constructor() {
        super();
        this.state = this.getInitialState();
    }

    getInitialState(): S {
        return { a: 3 } as S;
    }

    update() {
        this.setState({ a: 7 } as S);
    }
}

interface DerivedStates extends BaseStates {
    b: number;
}

class Derived extends GenericBase<DerivedStates> {
    getInitialState(): DerivedStates {
        var initialStates = super.getInitialState();
        initialStates.b = 4;
        return initialStates;
    }

    update() {
        this.setState({ a: 7, b: 4 });
    }
}

回答(1)

2 years ago

您可以使用类型断言在 Derived 中一次性设置状态的一些属性:

this.setState({ b: 4 } as DerivedStates); // do this
this.setState({ a: 7 } as DerivedStates); // or this
this.setState({ a: 7, b: 4 });            // or this

顺便说一下, getInitialState 不需要有不同的名字......你可以这么做:

class GenericBase<S extends BaseStates> extends React.Component<void, S> {
    constructor() {
        super();        
        this.state = this.getInitialState();
    }

    protected getInitialState() {
        return { a: 3 } as BaseStates as S;
    }
}

class Derived extends GenericBase<DerivedStates> {
    getInitialState() {
        var initialStates = super.getInitialState();
        initialStates.b = 4;
        return initialStates;
    }
}