next.js - 类型错误 : Cannot destructure property `req` of 'undefined' or 'null'

Question

我正在尝试让名为“With Apollo Auth”的 Next.js 示例正常工作:https://github.com/zeit/next.js/tree/master/examples/with-apollo-auth

我设置了所有内容，但出现错误:

TypeError: Cannot destructure property `req` of 'undefined' or 'null'.

const { AppTree, ctx: { req, res }} = ctx <----- Error line

此错误来自以下页面，该页面是 Next.js 提供的样板代码:

import initApollo from './initApollo'

function parseCookies (req, options = {}) {
  return cookie.parse(req ? req.headers.cookie || '' : document.cookie, options)
}

export default App => {
  return class WithData extends React.Component {
    // It is needed for better devtools experience. Check how react devtools shows it: "MyApp WithData"
    static displayName = `WithData(${App.displayName})`

    // Since apolloState is required but it is missed before this method returns the new props,
    // so it is needed to provide defaults
    static defaultProps = {
      apolloState: {}
    }

    static propTypes = {
      apolloState: PropTypes.object.isRequired
    }

    static async getInitialProps (ctx) {
      const { AppTree, ctx: { req, res }} = ctx
      const apollo = initApollo(
        {},
        {
          getToken: () => parseCookies(req).token
        }
      )

      ctx.ctx.apolloClient = apollo

      let appProps = {}
      if (App.getInitialProps) {
        appProps = await App.getInitialProps(ctx)
      }

      if (res && res.finished) {
        // When redirecting, the response is finished.
        // No point in continuing to render
        return {}
      }

      if (typeof window === 'undefined') {
        // Run all graphql queries in the component tree
        // and extract the resulting data
        try {
          // Run all GraphQL queries
          await getDataFromTree(<AppTree {...appProps} apolloClient={apollo} />)
        } catch (error) {
          // Prevent Apollo Client GraphQL errors from crashing SSR.
          // Handle them in components via the data.error prop:
          // https://www.apollographql.com/docs/react/api/react-apollo.html#graphql-query-data-error
          console.error('Error while running `getDataFromTree`', error)
        }

        // getDataFromTree does not call componentWillUnmount
        // head side effect therefore need to be cleared manually
        Head.rewind()
      }

      // Extract query data from the Apollo's store
      const apolloState = apollo.cache.extract()

      return {
        ...appProps,
        apolloState
      }
    }

    constructor (props) {
      super(props)
      // `getDataFromTree` renders the component first, the client is passed off as a property.
      // After that rendering is done using Next's normal rendering pipeline
      // @ts-ignore
      this.apolloClient = initApollo(props.apolloState, {
        getToken: () => {
          // @ts-ignore
          return parseCookies().token
        }
      })
    }

    render () {
      // @ts-ignore
      return <App apolloClient={this.apolloClient} {...this.props} />
    }
  }
}

我不确定为什么 ctx 未定义。

Answer 1

你做错了解构，修复以下

const { AppTree, req, res } = ctx;