如何通過從 axios 獲取，使用反應功能組件的 useState 中的數據

Question

我正在研究 jhipster 生成的反應項目。 當我從我的 rest api 執行獲取請求時。

GET http://localhost:8080/api/account
Accept: */*
Cache-Control: no-cache
Authorization: Bearer bearerValue

我得到這個答案：

HTTP/1.1 200 OK
Expires: 0
Cache-Control: no-cache, no-store, max-age=0, must-revalidate
X-XSS-Protection: 1; mode=block
Pragma: no-cache
X-Frame-Options: DENY
Referrer-Policy: strict-origin-when-cross-origin
Content-Security-Policy: default-src 'self'; frame-src 'self' data:; script-src 'self' 'unsafe-inline' 'unsafe-eval' https://storage.googleapis.com; style-src 'self' https://fonts.googleapis.com 'unsafe-inline'; img-src 'self' data:; font-src 'self' https://fonts.gstatic.com data:
Date: Sun, 05 Apr 2020 18:26:07 GMT
Connection: keep-alive
Vary: Origin
Vary: Access-Control-Request-Method
Vary: Access-Control-Request-Headers
X-Content-Type-Options: nosniff
Feature-Policy: geolocation 'none'; midi 'none'; sync-xhr 'none'; microphone 'none'; camera 'none'; magnetometer 'none'; gyroscope 'none'; speaker 'none'; fullscreen 'self'; payment 'none'
Transfer-Encoding: chunked
Content-Type: application/json

{
  "id": 3,
  "login": "admin",
  "firstName": "Administrator",
  "lastName": "Administrator",
  "email": "admin@localhost",
  "imageUrl": "",
  "activated": true,
  "langKey": "fr",
  "createdBy": "system",
  "createdDate": null,
  "lastModifiedBy": "system",
  "lastModifiedDate": null,
  "authorities": [
    "ROLE_USER",
    "ROLE_ADMIN"
  ]
}

這意味着 API 沒問題。 我的問題是我怎樣才能從我的 state 中的 axios promise 獲得結果，只執行一個請求。

這是我嘗試繼續的方法。

投資組合.tsx

export interface IPortfolioProps extends StateProps,
  DispatchProps,
  RouteComponentProps<{ url: string }> {
}

export interface AccountState {
  id: number,
  login: string,
  firstName: string,
  lastName: string,
  email: string,
  imageUrl: string,
  activated: boolean,
  langKey: string,
  createdBy: string,
  createdDate: string,
  lastModifiedBy: string,
  lastModifiedDate: string,
  authorities: Array<string>
}

export const Portfolio = (props: IPortfolioProps) => {

  const currentAccountState = async (): Promise<AccountState> => {
    return await axios.get<AccountState>(`/api/account`)
      .then((response) => {
        return response.data
      });
  };

  // eslint-disable-next-line @typescript-eslint/ban-ts-ignore
  // @ts-ignore
  const isAdmin: boolean = () => {
    let as: AccountState;
    currentAccountState()
      .then(response => {
        as = response;
        // eslint-disable-next-line no-console
        console.log('as : ', as);
        return as.authorities.find(
          authority => authority === AUTHORITIES.ADMIN) !== undefined;
      });
  };

  const [admin, setAdmin] = useState(isAdmin);

  return (
    <div>
      {`admin : ${admin}`}
    </div>);
}

運行應用程序時，我總是在屏幕上顯示“管理員：未定義”，而我的控制台登錄顯示正確的帳戶預期帳戶。 我想要保存為 state boolean 答案是當前用戶是管理員，在管理員 state 中。

Answer 1

我認為這是因為admin沒有默認值，所以admin在您從 API 收到響應之前首次呈現頁面時undefined 。 最好先用默認值初始化它，在掛載時調用 API，然后用響應更新 state。

您可以嘗試以下方法：

const [admin, setAdmin] = useState(null);

useEffect(() => {
    if (!admin) {
        const currentAccountState = async (): Promise<AccountState> => {
            return await axios.get<AccountState>(`/api/account`)
                .then((response) => {
                    return response.data
                });
        };
        currentAccountState()
            .then(response => {
                console.log('as : ', response );
                // probably add better handling here in the case that there is no result in the find, otherwise you mightrun into the same issue if admin is undefined again
                setAdmin(response.authorities.find(authority => authority === AUTHORITIES.ADMIN) !== undefined);
            });
    }
}, [admin])

return (
    <div>
        {`admin : ${admin}`}
    </div>
);