how are you?

Im doing a proof of concept using React and Cognito Hosted UI. I have this code here using react router dom:

return (
      <div>
        <main>
          <Switch>
          < Route path='/' exact>
              {
              (localStorage.getItem('access_token') && localStorage.getItem('access_token')!=='undefined') ? history.replace('/home'): (
                <div>
                  <b>You are not logged in Igor, please log in using Google or User and Password. </b>
                  <b></b>
                  <a href="https://<MY_DOMAIN>.auth.us-east-1.amazoncognito.com/login?client_id=<MY_CLIENT_ID>&response_type=code&scope=aws.cognito.signin.user.admin email openid phone profile&redirect_uri=<MY_CLOUDFRONT_DISTRIBUTION_APEX>">Sign in</a>
                </div>
              )
              }
            </Route>
            <Route path='/calculator'>
              <Calculator/>
            </Route>
            <Route path='/home/'>
              <Welcome/>
            </Route>
            <Route path='/welcome/'>
              <RedirectPage/>
            </Route>
          </Switch>
        </main>
      </div>
    ); 

Im using S3 as a static website hosting, thats why i point to S3 cloudfront distribution apex. Then, in my App function (residex inside App.js file), i make this validation every times the user access, to verify if this comes from a redirect, and if comes, i exchange the auth_code for a JWT token, that will be used with API Gateway:

      const location = useLocation();
      const history = useHistory();
      let authCode = new URLSearchParams(location.search).get('code');
      console.log(authCode)

      if(authCode){
        fetch('https://<GATEWAY_ID>.execute-api.us-east-1.amazonaws.com/dev/auth',{
              method: 'POST',
              body: JSON.stringify(authCode),
              headers: {
                'Content-Type': 'application/json'
              }
            }).then((res)=>{return res.json()}).then(data=>{
              console.log('access token is:');
              console.log(data.result['access_token']);
              console.log('id token is:');
              console.log(data.result['id_token']);
              localStorage.setItem('access_token',data.result['access_token']);
              history.replace('/home')
            });
      }

The problem is that after i make the authentication, either using google or login and password, i receive the code, i authenticate on cognito using a lambda on backend (on /dev/auth route, behind the Gateway), the lambda performs the authentication well, but my frontend page enters in a loop, and after print null a bunch of times (from the line console.log(authCode), i receive an error, telling that im in a loop). Im very newbie in react, im doing this POC to understand the concept and to show this proccess to a client.

Thanks in advance! I can't share the code as entire because that are stored in private company repository.

My complete code:

import React from 'react';
import { Route, Switch } from 'react-router-dom';
import Calculator from './pages/Calculator';
import Welcome from './pages/Welcome';
import {useHistory, useLocation} from 'react-router-dom';
import RedirectPage from './pages/Loading';

function App() {
      const location = useLocation();
      const history = useHistory();
      let authCode = new URLSearchParams(location.search).get('code');
      console.log(authCode)

      if(authCode){
        fetch('https://<GATEWAY_ID>.execute-api.us-east-1.amazonaws.com/dev/auth',{
              method: 'POST',
              body: JSON.stringify(authCode),
              headers: {
                'Content-Type': 'application/json'
              }
            }).then((res)=>{return res.json()}).then(data=>{
              console.log('access token is:');
              console.log(data.result['access_token']);
              console.log('id token is:');
              console.log(data.result['id_token']);
              localStorage.setItem('access_token',data.result['access_token']);
              history.replace('/home')
            });
      }
    
    return (
      <div>
        <main>
          <Switch>
          < Route path='/' exact>
              {
              (localStorage.getItem('access_token') && localStorage.getItem('access_token')!=='undefined') ? history.replace('/home'): (
                <div>
                  <b>You are not logged in Igor, please log in using Google or User and Password. </b>
                  <b></b>
                  <a href="<HOSTED_UI_COGNITO>">Sign in</a>
                </div>
              )
              }
            </Route>
            <Route path='/calculator'>
              <Calculator/>
            </Route>
            <Route path='/home/'>
              <Welcome/>
            </Route>
            <Route path='/welcome/'>
              <RedirectPage/>
            </Route>
          </Switch>
        </main>
      </div>
    ); 
}

export default App;

UPDATE 1: I think that the error is here:

localStorage.getItem('access_token') && localStorage.getItem('access_token')!=='undefined') ? history.replace('/home')

when the Lambda API returns an error, the workflow goes well, but the localStorage isn't filled with the JWT token.

I need to wait the response from the lambda function, insert JWT in localStorage, and then moves the user to /home url.

UPDATE 2: After some hours of debugging, and a lot of help, i finaly discover the problem. The problem was related to this line:

return (
      <div>
        <main>
          <Switch>
          < Route path='/' exact>
              {
              (localStorage.getItem('access_token') && localStorage.getItem('access_token')!=='undefined') ? history.replace('/home')

Cause we already have a useEffect statement that looks for the code and perform some actions, using this same code we enter in a loop statement. I just delete that and it works! thanks.

CodePudding user response：

I can see that you have written you api call code inside a functional component and i am assuming you want hit the api only once to achieve that you can write ur code inside useEffect

 useEffect(()=>{
    if(authCode){
        fetch('https://<GATEWAY_ID>.execute-api.us-east-1.amazonaws.com/dev/auth',{
              method: 'POST',
              body: JSON.stringify(authCode),
              headers: {
                'Content-Type': 'application/json'
              }
            }).then((res)=>{return res.json()}).then(data=>{
              console.log('access token is:');
              console.log(data.result['access_token']);
              console.log('id token is:');
              console.log(data.result['id_token']);
              localStorage.setItem('access_token',data.result['access_token']);
              history.replace('/home')
            });
      }
    
    },[authCode])