javascript - typescript 和 react-native 的 ForwardRef 错误

Question

使用 forwardRef 时出现ts 错误

// [ts] Property 'forwardRef' does not exist on type 'typeof React'.
const MyComponent = React.forwardRef((props: Props, ref: any) => ...

在 React Native 中，父组件抛出此错误:

Invariant Violation: Element type is invalid: expected a string (for build-in components) or a class/function (for composite components) but got: object

有什么解决办法吗？

Answer 1

根据definitions :

function forwardRef<T, P = {}>(Component: RefForwardingComponent<T, P>): ComponentType<P & ClassAttributes<T>>;
interface RefForwardingComponent<T, P = {}> {
    (props: P & { children?: ReactNode }, ref?: Ref<T>): ReactElement<any> | null;
    propTypes?: ValidationMap<P>;
    contextTypes?: ValidationMap<any>;
    defaultProps?: Partial<P>;
    displayName?: string;
}

ref 是可选参数，尝试以下操作:

在一个类中创建一个 ref 对象，其类型参数等于您想要的目标(在我的例子中是 div 但 View 也适用于 react-native)

private divRef: React.RefObject<div> = React.createRef();

在表示转发组件的 Prop 的界面中，将其作为可选属性公开

interface Props {
  ref?: React.RefObject<div>;
}

声明转发的组件类型为React.ComponentType

const ComponentWithForwardedRef: React.ComponentType<Props> = 
  React.forwardRef((props: Props, ref?: React.Ref<div>) => (
    <div ref={ref}>{props.message}</div>
  ));

创建具有转发 ref 的组件实例时，将创建的 ref 对象作为 prop 发送

<ComponentWithForwardedRef ref={this.divRef} />

一应俱全:

import * as React from "react";
import { render } from "react-dom";

interface Props {
  message: string;
  ref?: React.RefObject<div>;
}

const ComponentWithForwardedRef: React.ComponentType<Props> = 
  React.forwardRef((props: Props, ref?: React.Ref<div>) => (
    <div ref={ref}>{props.message}</div>
  ));

class App extends React.Component<Props> {
  private divRef: React.RefObject<div> = React.createRef();

  public componentDidMount() {
    const div = this.divRef.current;
    // check the console!
    console.log(div);
  }

  public render() {
    return (
      <ComponentWithForwardedRef ref={this.divRef} {...this.props} />
    )
  }
}

render(<App message="hello world" />, document.getElementById("root"));

后代链接:https://codesandbox.io/s/6v152q394k

依赖关系(引用目的)

"@types/react": "^16.3.11",
"@types/react-native": "^0.55.19",
"react-native": "0.55.2",
"typescript": "^2.8.1"