未捕获的不变违规：React.Children.only 预计会收到单个 React 元素子元素

Question

我正在尝试将一个函数传递给生成 menu

的子项

认为我早些时候被卡住了，因为那个例子似乎有一个父子，而我的中间有一个 HOC：

var comparator;
const GenericIsUserLoggedInLink = React.memo(({ isHomeButton, isLoggedIn, logOutUser, route, anchorText, mobile, name, selected, handleItemClick }) => {

 comparator = (prevProps, nextProps) => {

  if (prevProps.isHomeButton !== nextProps.setProps.isHomeButton) {
   return true;
  }
  if (prevProps.isLoggedIn !== nextProps.setProps.isLoggedIn) {
   return true;
  }
  if (prevProps.mobile !== nextProps.setProps.mobile) {
   return true;
  }
  if (prevProps.selected !== nextProps.setProps.selected) {
   return true;
  }
  return false;
 }

 function currentNav(route, name, selected, anchorText, handleItemClick) {
  const navItems = ['home', 'profile', 'dashboard'];
  return (
  <>
    <Link href={route}>
     {navItems.map(currentNavItem => (
      <Menu.Item
       key={currentNavItem}
       name={name}
       active={currentNavItem === selected ? true : false}
       onClick={() => handleItemClick(currentNavItem)}>
       {anchorText}
      </Menu.Item>
     ))}
    </Link>
  </>
  );
 }

 if (isHomeButton) {
  return currentNav(route, name, selected, anchorText, handleItemClick)
 }
 if (isLoggedIn) {
  if (anchorText === undefined) {
   return <Link href="/"><a onClick={() => logOutUser()}>Log out!</a></Link>
  }
  else if (mobile) {
   return currentNav(route, name, selected, anchorText, handleItemClick)
  }
  else if (!(mobile)) {
   return currentNav(route, name, selected, anchorText, handleItemClick)
  }

  else if (anchorText) {
   return <Link href={route}><a>{anchorText}</a></Link>
  }
 } else {
  if (route === "/login") {
   return <Link href="/login"><a>Log in!</a></Link>
  }
  return null
 }
}, comparator);



class DesktopContainer extends Component {
 state = {activeItem: 'home'}

 hideFixedMenu = () => this.setState({ fixed: false })
 showFixedMenu = () => this.setState({ fixed: true })
 handleItemClick = (activeItem) => this.setState({ activeItem })


 logOutUser = () => {
  const { logOutUser } = this.props
  logOutUser()
 }

 render() {
  const { GenericHeadingComponent, children, getWidth, isLoggedIn, logOutUser } = this.props


  const { fixed, activeItem } = this.state

  return (
   <Responsive getWidth={getWidth} minWidth={Responsive.onlyTablet.minWidth}>
    <Visibility
     once={false}
     onBottomPassed={this.showFixedMenu}
     onBottomPassedReverse={this.hideFixedMenu}
    >
     <Segment
      inverted
      textAlign='center'
      style={{ minHeight: 700, padding: '1em 0em' }}
      vertical
     >
      <Menu
       fixed={fixed ? 'top' : null}
       inverted={!fixed}
       pointing={!fixed}
       secondary={!fixed}
       size='large'
      >
       <Container>

        <GenericIsUserLoggedInLink
         isHomeButton={true}
         route="/"
         name='home'
         selected={activeItem}
         handleItemClick={this.handleItemClick}
         mobile={false}
        />

        <GenericIsUserLoggedInLink
         isLoggedIn={isLoggedIn}
         route="/profile"
         anchorText="Profile"
         name='profile'
         selected={activeItem}
         handleItemClick={this.handleItemClick}
         mobile={false}
        />

        <GenericIsUserLoggedInLink
         isLoggedIn={isLoggedIn}
         route="/dashboard"
         anchorText="Dashboard"
         name='dashboard'
         selected={activeItem}
         handleItemClick={this.handleItemClick}
         mobile={false}
        />


        <Menu.Item position='right'>
         <Button inverted={!fixed}>
          <GenericIsUserLoggedInLink
           route="/login"
           isLoggedIn={isLoggedIn}
           logOutUser={logOutUser}
           />
         </Button>
         <Button inverted={!fixed} primary={fixed} style={{ marginLeft: '0.5em' }}>
          <Link href="/register">
           <a>Register</a>
          </Link>
         </Button>
        </Menu.Item>
       </Container>
      </Menu>
      <GenericHeadingComponent />
     </Segment>
    </Visibility>

    {children}
   </Responsive>
  )
 }
}

DesktopContainer.propTypes = {
 children: PropTypes.node,
}

class MobileContainer extends Component {
 state = { activeItem: 'home' }

 handleSidebarHide = () => this.setState({ sidebarOpened: false })

 handleToggle = () => this.setState({ sidebarOpened: true })
 handleItemClick = (activeItem) => this.setState({ activeItem })

 logOutUser = () => {
  const { logOutUser } = this.props
  logOutUser()
 }

 render() {
  const { GenericHeadingComponent, children, getWidth, isLoggedIn, logOutUser, mobile } = this.props
  const { sidebarOpened, activeItem } = this.state

  return (
   <Responsive
    as={Sidebar.Pushable}
    getWidth={getWidth}
    maxWidth={Responsive.onlyMobile.maxWidth}
   >
    <Sidebar
     as={Menu}
     animation='push'
     inverted
     onHide={this.handleSidebarHide}
     vertical
     visible={sidebarOpened}
    >

     <GenericIsUserLoggedInLink
      isHomeButton={true}
      route="/"
      name='home'
      anchorText="Home"
      selected={activeItem}
      handleItemClick={this.handleItemClick}
      mobile={true}
     />

     <GenericIsUserLoggedInLink
      isLoggedIn={isLoggedIn}
      route="/profile"
      anchorText="Profile"
      name='profile'
      selected={activeItem}
      handleItemClick={this.handleItemClick}
      mobile={true}
     />

     <GenericIsUserLoggedInLink
      isLoggedIn={isLoggedIn}
      route="/dashboard"
      anchorText="Dashboard"
      name='dashboard'
      selected={activeItem}
      handleItemClick={this.handleItemClick}
      mobile={true}
     />

     <Menu.Item>
      <GenericIsUserLoggedInLink
       route="/login"
       isLoggedIn={isLoggedIn}
       logOutUser={logOutUser}
      />
     </Menu.Item>
     <Menu.Item >
      <Link href="/register">
       <a>Register</a>
      </Link>
     </Menu.Item>
    </Sidebar>

    <Sidebar.Pusher dimmed={sidebarOpened}>
     <Segment
      inverted
      textAlign='center'
      style={{ minHeight: 350, padding: '1em 0em' }}
      vertical
     >
      <Container>
       <Menu inverted pointing secondary size='large'>
        <Menu.Item onClick={this.handleToggle}>
         <Icon name='sidebar' />
        </Menu.Item>
       </Menu>
      </Container>
      <GenericHeadingComponent mobile={mobile} />
     </Segment>
     {children}
    </Sidebar.Pusher>
   </Responsive>
  )
 }
}

MobileContainer.propTypes = {
 children: PropTypes.node,
}

这个错误是在我的 <DesktopContainer/> 和 <MobileContainer/> 组件中引起的。

这些是错误：

index.js:1 The above error occurred in the <Link> component:
    in Link
    in Unknown (created by MobileContainer)
    in div (created by Menu)
    in Menu (created by Sidebar)
    in RefFindNode (created by Ref)
    in Ref (created by Sidebar)
    in Sidebar (created by MobileContainer)
    in div (created by SidebarPushable)
    in SidebarPushable (created by Responsive)
    in Responsive (created by MobileContainer)
    in MobileContainer (created by LayoutComponent)
    in LayoutComponent (created by Connect(LayoutComponent))
    in Connect(LayoutComponent) (created by HomepageLayout)
    in HomepageLayout (created by Connect(HomepageLayout))
    in Connect(HomepageLayout) (created by Home)
    in Home (created by Connect(Home))
    in Connect(Home) (created by MyApp)
    in PersistGate (created by MyApp)
    in Provider (created by MyApp)
    in MyApp (created by AppWithRedux)
    in AppWithRedux
    in Suspense (created by AppContainer)
    in Container (created by AppContainer)
    in AppContainer

VM451 main.js:12445 The above error occurred in the <Link> component:
    in Link
    in Unknown (created by DesktopContainer)
    in div (created by Container)
    in Container (created by DesktopContainer)
    in div (created by Menu)
    in Menu (created by DesktopContainer)
    in div (created by Segment)
    in Segment (created by DesktopContainer)
    in div (created by Visibility)
    in RefFindNode (created by Ref)
    in Ref (created by Visibility)
    in Visibility (created by DesktopContainer)
    in div (created by Responsive)
    in Responsive (created by DesktopContainer)
    in DesktopContainer (created by LayoutComponent)
    in LayoutComponent (created by Connect(LayoutComponent))
    in Connect(LayoutComponent) (created by HomepageLayout)
    in HomepageLayout (created by Connect(HomepageLayout))
    in Connect(HomepageLayout) (created by Home)
    in Home (created by Connect(Home))
    in Connect(Home) (created by MyApp)
    in PersistGate (created by MyApp)
    in Provider (created by MyApp)
    in MyApp (created by AppWithRedux)
    in AppWithRedux
    in Suspense (created by AppContainer)
    in Container (created by AppContainer)
    in AppContainer

VM453 dll_397dc449097af0b4e992.js:26942 Uncaught Invariant Violation: React.Children.only expected to receive a single React element child.
    at http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:26942:26
    at Object.onlyChild [as only] (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:26945:5)
    at Link.render (http://localhost:8016/_next/static/development/pages/index.js?ts=1572206599026:25504:35)
    at finishClassComponent (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:17380:31)
    at updateClassComponent (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:17335:24)
    at beginWork (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:18846:16)
    at HTMLUnknownElement.callCallback (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:688:14)
    at Object.invokeGuardedCallbackDev (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:738:16)
    at invokeGuardedCallback (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:795:31)
    at beginWork$ (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:23558:7)
    at performUnitOfWork (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:22549:12)
    at workLoopSync (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:22526:22)
    at renderRoot (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:22219:11)
    at scheduleUpdateOnFiber (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:21760:22)
    at scheduleRootUpdate (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:24660:3)
    at updateContainerAtExpirationTime (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:24688:10)
    at updateContainer (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:24777:10)
    at http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:25304:7
    at unbatchedUpdates (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:22028:12)
    at legacyRenderSubtreeIntoContainer (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:25303:5)
    at Object.hydrate (http://localhost:8016/_next/static/development/dll/dll_397dc449097af0b4e992.js?ts=1572206599026:25370:12)
    at renderReactElement (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:9362:26)
    at _callee4$ (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:9494:13)
    at tryCatch (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:698:40)
    at Generator.invoke [as _invoke] (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:924:22)
    at Generator.prototype.<computed> [as next] (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:750:21)
    at asyncGeneratorStep (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:226:24)
    at _next (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:248:9)
    at http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:255:7
    at new Promise (<anonymous>)
    at new F (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:2352:28)
    at http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:244:12
    at _doRender (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:9508:20)
    at doRender (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:9437:20)
    at _callee2$ (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:9247:20)
    at tryCatch (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:698:40)
    at Generator.invoke [as _invoke] (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:924:22)
    at Generator.prototype.<computed> [as next] (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:750:21)
    at asyncGeneratorStep (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:226:24)
    at _next (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:248:9)
    at http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:255:7
    at new Promise (<anonymous>)
    at new F (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:2352:28)
    at http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:244:12
    at _render (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:9268:18)
    at render (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:9219:18)
    at _callee$ (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:9200:13)
    at tryCatch (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:698:40)
    at Generator.invoke [as _invoke] (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:924:22)
    at Generator.prototype.<computed> [as next] (http://localhost:8016/_next/static/runtime/main.js?ts=1572206599026:750:21)

谁能发现我可以在哪里包装 <></> 来解决这个错误？

Answer 1

Link from Next.js 期望 one children，如果提供多个 children 将抛出错误。

您可以用 a 标签包裹多个 children：

<Link href={route}>
  <a>
    {navItems.map(currentNavItem => (
      <Menu.Item
        key={currentNavItem}
        name={name}
        active={currentNavItem === selected ? true : false}
        onClick={() => handleItemClick(currentNavItem)}>
        {anchorText}
      </Menu.Item>
    ))}
 </a>
</Link>

Answer 2

if 在 next.js

中给出错误

  <Link href="/"><a> Home </a></Link>

试试下面对我有用的方法

 <Link href="/">
 <a> Home </a>
 </Link>

未捕获的不变违规：React.Children.only 预计会收到单个 React 元素子元素

Uncaught Invariant Violation: React.Children.only expected to receive a single React element child

javascript

reactjs

react-props

higher-order-components

react-state