Converting a class based component to hooks (gapi API)

问题

I have this class based component using the gapi (Google Auth) API that renders a button and it works:

import React from 'react';

class GoogleAuth extends React.Component {
  state = { isSignedIn: null };

  componentDidMount() {
    window.gapi.load('client:auth2', () => {
      window.gapi.client
        .init({
          clientId: process.env.REACT_APP_CLIENT_ID,
          scope: 'email',
        })
        .then(() => {
          this.auth = window.gapi.auth2.getAuthInstance();
          this.handleAuthChange();
          this.auth.isSignedIn.listen(this.handleAuthChange);
        });
    });
  }

  handleAuthChange = () => {
    this.setState({ isSignedIn: this.auth.isSignedIn.get() });
  };

  handleSignIn = () => {
    this.auth.signIn();
  };

  handleSignOut = () => {
    this.auth.signOut();
  };

  renderAuthButton() {
    if (this.state.isSignedIn === null) {
      return null;
    } else if (this.state.isSignedIn) {
      return <button onClick={this.handleSignOut}>Sign Out</button>;
    } else {
      return <button onClick={this.handleSignIn}>Sign in with Google</button>;
    }
  }

  render() {
    return <div>{this.renderAuthButton()}</div>;
  }
}

export default GoogleAuth;

I'm having a tough time trying to convert this to use hooks. The main issue is this.auth... That's how the class has a reference to window.gapi.auth2.getAuthInstance()

I have tried many different ways including keeping auth in state like:

export default function GoogleAuth() {
    const [isSignedIn, setIsSignedIn] = useState(null);
    const [auth, setAuth] = useState(null);
    useEffect(() => {
        window.gapi.load('client:auth2', () => {
            window.gapi.client
                .init({
                    clientId: process.env.REACT_APP_CLIENT_ID,
                    scope: 'email',
                })
                .then(() => {
                    setAuth(window.gapi.auth2.getAuthInstance());
                    setIsSignedIn(auth.isSignedIn.get());
                    auth.isSignedIn.listen(() => setIsSignedIn(auth.isSignedIn.get()));
                });
        });
    }, [auth]);

回答1:

Couple issues - you're referencing auth immediately after you're setting the state - auth won't be set until it re-renders with its new state.

I'm playing with similar code, and I had to resort to utilizing window.gapi in the initial setup to properly access the returned auth instance.

I imagine it may throw an error if a user clicks quickly they could catch it before auth is set, but I found the sign in/out functions to be able to handle this.

I also found it easiest to test in Incognito, as cookies and cacheing of the api seemed to create an unpredictable local testing environment.

My current component state

回答2:

It's only 8 months later but try useRef with auth like below. It works for me.

   const GoogleAuth  = () => {
      const [isSignedIn, setSignedIn] = useState(null)
      const auth = useRef(null);
      useEffect(() => {
        window.gapi.load('client:auth2', () => {
          window.gapi.client.init({
            clientId:
              'jcu.apps.googleusercontent.com',
            scope: 'email'
          }).then(() => {
            auth.current = window.gapi.auth2.getAuthInstance();
            setSignedIn(auth.current.isSignedIn.get());
            auth.current.isSignedIn.listen(onAuthChange)
          });
        });
      }, [isSignedIn]);
    
     const onAuthChange = () => {
          setSignedIn(auth.current.isSignedIn.get())
      }
    
     if (isSignedIn === null) {
        return (
          <div>I don't know if we are signed in!</div>
        );
      } else if ( isSignedIn ){
        return (
          <div>I am signed in!</div>
        );
      } else {
        return ( <div>I am not signed in. :(</div>);
      }
    }

来源：https://stackoverflow.com/questions/55961293/converting-a-class-based-component-to-hooks-gapi-api