React with TypeScript: Type '{}' is not assignable to type

Question

I have a component in React that shows a navigation based on a prop. I cannot figure out why I am getting this error when I'm trying to run the application:

(19,8): Type '{}' is not assignable to type 'IntrinsicAttributes & IntrinsicClassAttributes<TableSystems> & Readonly<{ children?: ReactNode; }...'.
  Type '{}' is not assignable to type 'Readonly<{ todos: any; showNav: boolean; }>'.
    Property 'todos' is missing in type '{}'.

My component look like this:

import * as React from 'react'
import Navigation from '../components/Navigation'
import TableSystems from '../components/TableSystems'

class SystemTable extends React.PureComponent<{showNav: boolean }> {
  render(){
  return (

    <div >
    <div >
    <div className="navigationContainer">
    <Navigation {...this.props.showNav} className="sideMenu"/>
      <TableSystems/>
      </div>
    </div>
  </div>)
  }
}


export default SystemTable

I can't find what's the problem here.

The component looks like this:

import * as React from 'react';
import history from '../history';


class Navigation extends React.Component<any>  {

constructor(props){
    super(props);
    this.toVersions = this.toVersions.bind(this);
  }

  toVersions(){
    history.push('/versions');
  }

  render() {
    var style = this.props.visible ? "toggled" : "";
    console.log(style);
    return (
      <div className={style} id="wrapper">


        <div id="sidebar-wrapper">
          <ul className="sidebar-nav">
            <li className="sidebar-brand">
              <a href="#">
                Menu
              </a>
            </li>
            <li >
              <a className="nav-link" href="#">List1</a>
            </li>
            <li >
              <a className="nav-link" href="#">List2</a>
            </li>
            <li >
              <a className="nav-link" href="" onClick={this.toVersions}>List3</a>
            </li>
            <li >
              <a className="nav-link" href="#">List4</a>
            </li>
          </ul>
        </div>
      </div>
    )
  }
}

export default Navigation

Answer 1

您需要通过将属性todos定义为todos?: any使其成为可选属性，否则必须将值传递给它： { todos: null, showNav: boolean } 。

Answer 2

While I can only guess the element throwing the error (no clue where line 19 is), the error is quite self explanatory:

Type '{}' is not assignable to type 'Readonly<{ todos: any; showNav: boolean; }>'. Property 'todos' is missing in type '{}'.

The component expects a todo property and a showNav property, you are providing none of these. Try specifying the props explicitly:

<YourElement todos={ this.props.whatever } showNav={true}> ... </YourElement>

Another solution is to use the spread operator to use an objects properties for the element's props:

const someVar = { todos: "your type for todos here", showNav: true };

<YourElement { ...someVar } \>

Ensure you also type your element's props:

interface Props {
    prop: string;
}

const SampleElement: React.SFC<Props> = (props) =>
    <div>{props.prop}</div>

class AnotherElement extends React.Component<Props> { ... }

Answer 3

因此解决方案是将{... this.props}添加到组件中，如下所示：

<TableSystems {...this.props}/>