Question

我一直收到此错误“ TypeError：无效的尝试去破坏不可迭代的实例的结构”，并且我不确定出什么问题了。我正在使用React和Context API，这是我的代码。不知道我是否想念错字了？

Store.tsx


interface IState {
    episodes: [],
    favourites: []
}

interface IAction {
    type: string,
    payload: any
}

const initialState: IState = {
    episodes: [],
    favourites: []
}


export const Store = React.createContext<IState | any>(initialState)

function reducer(state: IState, action: IAction): IState {
    switch (action.type) {
        case 'FETCH_DATA':
            return {...state, episodes: action.payload }
        default:
            return state
    }
}



export function StoreProvider(props: any): JSX.Element {
    const [state, dispatch] = React.useReducer(reducer, initialState)
    return <Store.Provider value={{state, dispatch}}>{props.children}</Store.Provider>
}

App.tsx

import React, { useEffect } from 'react'
import { Store } from './Store'


export default function App():JSX.Element {
  const [state, dispatch] = React.useContext(Store)

  useEffect(() => {
    state.episodes.length() === 0 && fetchDataAction()
  })

  const fetchDataAction = async () => {
    const URL = 'https://api.tvmaze.com/singlesearch/shows?q=the-office&embed=episodes'
    const data = await fetch(URL)
    const dataJSON = await data.json()
    return dispatch({
      type: 'FETCH_DATA',
      payload: dataJSON._embedded.episodes
    })
  }
  console.log(state)

  return (
    <>
      <h1>Rick and Morty</h1>
      <p>Pick your favourite episode</p>
    </>
  )
}

Index.tsx

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import { StoreProvider } from './Store'


ReactDOM.render(
<StoreProvider>
<App />
</StoreProvider>, document.getElementById('root'));

任何帮助将不胜感激。谢谢

Answer 1

弄清楚，只需将select * from Pet_Owner where Owner_id in ( select Owner_id from Pet where Pet_id in (select Pet_id in Booking) and PType='DOG' group by owner_id having count(1) >= 2) ) order by Owner_id更改为const [state, dispatch] = React.useContext(Store)

在React

1 个答案: