React Application Update Data from DynamoDB Change

Assuming you are using Cognito as your authentication for your AppSync application, you could set a lambda trigger on the dynamo table that generates a cognito token, and uses that make an authorized request to your mutation endpoint. NOTE: in your cognito userpool>app clients page, you will need to check the Enable username password auth for admin APIs for authentication (ALLOW_ADMIN_USER_PASSWORD_AUTH) box to generate a client secret.

const AWS = require('aws-sdk');
const crypto = require('crypto');
var jwt = require('jsonwebtoken');


const secrets = require('./secrets.js');
var cognitoidentityserviceprovider = new AWS.CognitoIdentityServiceProvider();
var config;





const adminAuth = () => new Promise((res, rej) => {

        const digest = crypto.createHmac('SHA256', config.SecretHash)
          .update(config.userName + config.ClientId)
          .digest('base64');

        var params = {
          AuthFlow: "ADMIN_NO_SRP_AUTH",
          ClientId: config.ClientId, /* required */
          UserPoolId: config.UserPoolId, /* required */
          AuthParameters: {
            'USERNAME': config.userName,
            'PASSWORD': config.password,
            "SECRET_HASH":digest
          },
        };
        cognitoidentityserviceprovider.adminInitiateAuth(params, function(err, data) {
          if (err) {
              console.log(err.stack);
              rej(err);
          }
          else {

              data.AuthenticationResult ? res(data.AuthenticationResult) : rej("Challenge requested, to verify, login to app using admin credentials");
          }
        }); 
});

const decode = auth => new Promise( res => {
    const decoded = jwt.decode(auth.AccessToken);
    auth.decoded = decoded
    res(auth);
});


//example gql query

 const testGql = auth =>  {
     const url = config.gqlEndpoint;

     const payload  = {
         query: `
           query ListMembers {
             listMembers {
               items{
                 firstName
                 lastName
               }
             }
           }
         ` 
     };


     console.log(payload);      
     const options = {
         headers: {
           "Authorization": auth.AccessToken
         },
     };

     console.log(options);
     return axios.post(url, payload, options).then(data =>  data.data)
     .catch(e => console.log(e.response.data));
 };






exports.handler = async (event, context, callback) => {
   await secrets() //some promise that returns your keys object (i use secrets manager)
   .then( keys => {
       #keys={ClientId:YOUR_COGNITO_CLIENT, 
       #      UserPoolId:YOUR_USERPOOL_ID,
       #      SecretHash:(obtained from cognito>userpool>app clients>app client secret),
       #      gqlEndpoint:YOUR_GRAPHQL_ENDPOINT,
       #      userName:YOUR_COGNITO_USER,
       #      password:YOUR_COGNITO_USER_PASSWORD,
       #      }

       config = keys
       return adminAuth()
   })
   .then(auth => {
       return decode(auth)
   })
   .then(auth => {
       return testGql(auth)
   })
   .then( data => {
       console.log(data)
       callback(null, data)
   })
   .catch( e => {
       callback(e)
   })
};