Dialogflow easy way for authorization

Does exist an easy way to connect Dialogflow agent to node.js code? When I use this code with the correct projectID taken from the Dialogflow agent's settings page, I have the following error:

Error: Unexpected error while acquiring application default credentials: Could not load the default credentials. Browse to https://developers.google.com/accounts/docs/application-default-credentials for more information.

const sessionClient = new dialogflow.SessionsClient();
const sessionPath = sessionClient.sessionPath(projectId, sessionId);

I visited the page, but for what I want I think is quite confused (they quotes other API and a lot of setting), how can I solve this?

I want to take informations from a file and loading all without installing third party APIs.

It is not very well documented, but the easiest way to authenticate is using the JSON file provided on your google cloud platform console.

const sessionClient = new dialogflow.SessionsClient({
    keyFilename: '/path/to/google.json'
});
const sessionPath = sessionClient.sessionPath(projectId, sessionId);

This also works for all the other clients. ContextsClients, EntityTypesClient and so on.

I am writing the code, which worked for me. Please follow all the steps provided in Reference link 2 and for coding purpose you can use the snippet provided.

I have also added the sample JSON of Google Cloud Oauth

References:

1. https://www.npmjs.com/package/dialogflow#samples
2. https://medium.com/@tzahi/how-to-setup-dialogflow-v2-authentication-programmatically-with-node-js-b37fa4815d89

//Downloaded JSON format

{
  "type": "service_account",
  "project_id": "mybot",
  "private_key_id": "123456asd",
  "private_key": "YOURKEY",
  "client_email": "[email protected]",
  "client_id": "098091234",
  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
  "token_uri": "https://oauth2.googleapis.com/token",
  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/yourID%40mybot.iam.gserviceaccount.com"
}


//------*********************---------------------------
//
const projectId = 'mybot';

//https://dialogflow.com/docs/agents#settings
// generate session id (currently hard coded)
const sessionId = '981dbc33-7c54-5419-2cce-edf90efd2170';
const query = 'hello';
const languageCode = 'en-US';

// Instantiate a DialogFlow client.
const dialogflow = require('dialogflow');
let privateKey = 'YourKey';

// as per goolgle json
let clientEmail = "[email protected]";
let config = {
  credentials: {
    private_key: privateKey,
    client_email: clientEmail
  }
}
const sessionClient = new dialogflow.SessionsClient(config);

// Define session path
const sessionPath = sessionClient.sessionPath(projectId, sessionId);

// The text query request.
const request = {
  session: sessionPath,
  queryInput: {
    text: {
      text: query,
      languageCode: languageCode,
    },
  },
};

// Send request and log result
sessionClient
  .detectIntent(request)
  .then(responses => {
    console.log('Detected intent');
    const result = responses[0].queryResult;
    console.log(`  Query: ${result.queryText}`);
    console.log(`  Response: ${result.fulfillmentText}`);
    if (result.intent) {
      console.log(`  Intent: ${result.intent.displayName}`);
    } else {
      console.log(`  No intent matched.`);
    }
  })
  .catch(err => {
    console.error('ERROR:', err);
  });

I have the same issue few months ago, check this, this is how i solve it. From your JSON that Google Cloud extract this lines.

const dialogflow = require('dialogflow');
const LANGUAGE_CODE = 'en-US'
const projectId = 'projectid';
const sessionId = 'sessionId';
const query = 'text to check';


let privateKey = "private key JSON";
let clientEmail = "email acount from JSON";
let config = {
credentials: {
    private_key: privateKey,
    client_email: clientEmail
}
};

sessionClient = new dialogflow.SessionsClient(config);

async function sendTextMessageToDialogFlow(textMessage, sessionId) {
// Define session path
const sessionPath = this.sessionClient.sessionPath(projectId, sessionId);
// The text query request.
const request = {
    session: sessionPath,
    queryInput: {
        text: {
            text: textMessage,
            languageCode: LANGUAGE_CODE
        }
    }
}
try {
    let responses = await this.sessionClient.detectIntent(request)
    console.log('DialogFlow.sendTextMessageToDialogFlow: Detected intent', responses);
    return responses
} catch (err) {
    console.error('DialogFlow.sendTextMessageToDialogFlow ERROR:', err);
    throw err
}
};


sendTextMessageToDialogFlow(query, sessionId)

Since the original question, the documentation for Dialogflow authentication has been improved. You should find all your answers here:

Authentication and access contro

I follow the above solutions with little changes :

// A unique identifier for the given session
const sessionId = uuid.v4();

// Create a new session

const sessionClient = new dialogflow.SessionsClient({
    keyFilename: require("path").join('config/google-credential.json')
});
const sessionPath = sessionClient.sessionPath(process.env.DIALOGFLOW_PROJECTID, sessionId);