Parent update causes remount of context consumer?

问题

I have a wrapper component that creates a context consumer and passes the context value as a prop to a handler component. When the parent of the wrapper component updates, it's causing my handler component to remount instead of just update.

const Wrapper = forwardRef((props, ref) => {
  class ContextHandler extends Component {
    componentDidMount() {
      // handle the context as a side effect
    }

    render() {
      const { data, children } = this.props;
      return (
        <div ref={ref} {...data}>{children}</div>
      );
    }
  }
  return (
    <Context.Consumer>
      {
        context => (
          <ContextHandler
            data={props}
            context={context}
          >
            {props.children}
          </ContextHandler>
        )
      }
    </Context.Consumer>
  );
});

I put the wrapper inside a parent component:

class Parent extends Component {

  state = {
    toggle: false
  }

  updateMe = () => {
    this.setState(({toggle}) => ({toggle: !toggle}))
  }

  render() {
    const { children, data } = this.props;
    return (
      <Wrapper
        onClick={this.updateMe}
        {...data}
        ref={me => this.node = me}
      >
        {children}
      </Wrapper>
    )
  }
}

When I click on the Wrapper and cause an update in Parent, the ContextHandler component remounts, which causes its state to reset. It should just update/reconcile and maintain state.

What am I doing wrong here?

回答1:

Your ContextHandler class is implemented within the render function of the Wrapper component which means that an entirely new instance will be created on each render. To fix your issue, pull the implementation of ContextHandler out of the render function for Wrapper.

来源：https://stackoverflow.com/questions/55483564/parent-update-causes-remount-of-context-consumer