Calling a rest API from one Org to another Org?

Question

I have created Connected App & Auth Provider.
This is the Code i am currently running. Getting error. What I am doing wrong?
Can anyone please help me with this?

1st Org - (Class which will get 10 Account details)

@RestResource(urlMapping='/v1/getAccounts/*')
global with sharing class FetchAccount {
@HttpGet
    global static list<account> fetchAccount(){
        RestRequest req = RestContext.request;
        RestResponse res = Restcontext.response;
        List<account> listAccount =[Select Id , Name from Account LIMIT 10 ];
        return listAccount ;
    }
}

2nd Org - (REST API which is calling method from 1st Org)

public class AccountRestExampleConsumeFromOtherSFOrg{

public String AccountRestExampleConsumeFromOtherSFOrg(){

String endpoint='https://login.salesforce.com/services/oauth2/token';

String username = '*******'; 
String password = '********';
String ClientId= '********************';
String ClientSecret = '***************'; 

Httprequest req = new HttpRequest();    
req.setMethod('POST');    
//req.setHeader('Content-Type','application/json');

req.setBody('grant_type=password + &client_id=' + ClientId + '&client_secret=' + ClientSecret + '&username=' + username +'&password=' + password); 

req.setEndpoint(endpoint);
//req.setHeader('Authorization', 'OAuth '+UserInfo.getSessionId());
Http http = new Http();
HttpResponse res;       
String Access_Token;
try {
res = http.send(req);                
system.debug('body:'+res.getBody());  
JSONParser parser = JSON.createParser(res.getBody());
while (parser.nextToken() != null) {
    if ((parser.getCurrentToken() == JSONToken.FIELD_NAME) && (parser.getText() == 'access_token')) {
            parser.nextToken();
            Access_Token = parser.getText();    
            } 
    }            
}catch(system.CalloutException e){            
system.debug('error'+e);
}
system.debug('access token'+Access_Token);
Httprequest req1 = new HttpRequest();  
req1.setEndpoint('https://einsteinpersi-dev- 
ed.my.salesforce.com/services/apexrest/v1/getAccounts');  
req1.setMethod('GET');    
req1.setHeader('Content-Type','application/x-www-form-urlencoded');
req1.setHeader('Authorization','Bearer '+Access_Token);            
Http http1 = new Http();
HttpResponse res1 = http1.send(req1);                 
system.debug('body11:'+res1.getBody()); 
return res1.getBody();
}
}

Error I am getting -

Answer 1

There are 2 things wrong in your callout in 2nd org.

1. Set body is not proper,

   req.setBody('grant_type=password&client_id=' + ClientId + '&client_secret=' + ClientSecret + '&username=' + username +'&password=' + password); 
   

2. You don't have to set Authorization header as Session ID from Source org to get access token. Remove that.

Src: https://developer.salesforce.com/docs/atlas.en-us.api_rest.meta/api_rest/intro_understanding_username_password_oauth_flow.htm

Answer 2

Finally understood what was the issue. Solved the problem.
Although, the error it was showing was - "Invalid grant_type", actually I was not able to call API in another Org because 'Access Token' wasn't getting generated.

Answer - I had to append my Org's "Security Token" with my Org password....!!!!!

Till now I was only passing Org password in req.setBody().
Rest of the code absolutely correct & no changes required.

Answer 3

You must append the user’s security token to their password A security token is an automatically-generated key from Salesforce. For example, if a user's password is mypassword, and their security token is XXXXXXXXXX, then the value provided for this parmeter must be mypasswordXXXXXXXXXX. For more information on security tokens see “Reset Your Security Token” in the online help.enter link description here

Answer 4

Update your setBody method by

req.setBody('grant_type=password&client_id=' + ClientId + '&client_secret=' + ClientSecret + '&username=' + username +'&password=' + password); 

Refer the format here: https://developer.salesforce.com/docs/atlas.en-us.api_rest.meta/api_rest/intro_understanding_username_password_oauth_flow.htm