反应钩子“useSelector"在函数中调用

问题描述

我无法弄清楚useSelector"发生了什么，我需要一点帮助.

I cannot figure out what going on with "useSelector" I need little help, please.

错误

React Hook "useSelector" 在函数 "render_user" 中调用，该函数既不是 React 函数组件，也不是自定义的 React Hook 函数

class Navigationbar extends Component {

  onLogoutClick = e => {
    e.preventDefault();
    this.props.logoutUser(); //this.props.
  };

  render() {
      const render_user = () => {

        const auth = useSelector(state => state.auth); Error Message is here
        //More Code Here
      );
    };
  }

Navigationbar.propTypes = {
  logoutUser: PropTypes.func.isRequired,
  auth: PropTypes.object.isRequired
};

const mapStateToProps = state => ({
  auth: state.auth
});

export default connect(
  mapStateToProps,
  { logoutUser }
)(Navigationbar);

推荐答案

该错误是由于您违反了 钩子规则:

The error is due to the fact that you violated the rules of hooks:

• 仅在顶层调用挂钩
• 仅从 React 函数调用钩子

违规行为:

1. useSelector() 不在顶层调用.它在 render() 中的 render_user() 中调用(即嵌套函数).
2. useSelector() 是类组件的一部分，Navigationbar

1. useSelector() is not called in top-level. It is called in render_user() in render() (i.e nested function).
2. useSelector() is part of a class component, Navigationbar

你可以提取一个组件来遵循钩子的规则并使用useSelector:

You can extract a component to follow the rules of hooks and make use of useSelector:

function User() { // Rule 2: call hooks in function component
  const auth = useSelector(state => state.auth); // Rule 1: call hooks in top-level
  return <>{auth}</>
}

class Navigationbar extends Component {

  render_user() {
    if (props.authenticated) {
      return <User />
    }
    // not yet authenticated
    // do something else
  }

  render() {
    return <>{this.render_user()}</>
  }
}

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