How to make callout from a batch class without Statuscode 500

Question

I have a batch class which basically does a soql of to get a list of account records. In the execute, i want to get the list returned and pass them to a Http callout function which will do a Post request to insert the list into another org. If I run:

moveObjectsToNewOrg b = new moveObjectsToNewOrg();
Database.executeBatch(b, 50);

i get a callout response of: System.HttpResponse[Status=Server Error, StatusCode=500]

However, when i try:

Account acct1 = new Account(Name='Dummy 1');  
Account acct2 = new Account(Name='Dummy 2');  
List<Account> accList = new List<Account>{acct1, acct2};
submitDataToTargetOrg.submitDataUsingRest(accList);

it works perfectly with a statuscode 200. Here is what my batch class looks like :

global class moveObjectsToNewOrg implements Database.Stateful, Database.Batchable<sObject>, Database.AllowsCallouts{

    public Database.QueryLocator start(Database.BatchableContext context){
        if (LOG_THIS_CLASS) System.debug('starting batch.. : ' + context);
        return Database.getQueryLocator('SELECT Id, Name FROM Account WHERE Name LIKE \'Dummy%\'');
    }

    public void execute(Database.BatchableContext context, List<SObject> scope){
        submitDataToTargetOrg.submitDataUsingRest((List<Account>)scope);
    }

    public Void finish(Database.BatchableContext context){}
    }

I call this function which is outside of the batch class:

public static HttpRequest submitDataUsingRest(List<SObject> recordsToTransfer) {
    Schema.SObjectType sObjectType = recordsToTransfer.getSObjectType();
        HttpRequest req;
        if (sObjectType != null){
            String listType = 'List<' + sObjectType + '>';
            List<SObject> castRecords = (List<SObject>)Type.forName(listType).newInstance();
            castRecords.addAll(recordsToTransfer);
            String reqbody = 'grant_type=password&client_id='+clientId+'&client_secret='+clientSecret+'&username='+userName+'&password='+password;

            Http http = new Http();
            req = new HttpRequest();
            req.setBody(reqbody);
            req.setMethod('POST');
            req.setEndpoint('https://eu6.salesforce.com/services/oauth2/token');

            HttpResponse res = http.send(req);
            OAuth2 objAuthenticationInfo = (OAuth2)JSON.deserialize(res.getbody(), OAuth2.class);

            if(objAuthenticationInfo.access_token!=null){
                String requestBody = '{"req":{"accounts":'+JSON.serialize(castRecords)+'}}';
                Http http2 = new Http();
                HttpRequest req1 = new HttpRequest();
                string endP = 'https://eu6.salesforce.com/services/apexrest/getAccountData';
                req1.setHeader('Authorization','Bearer ' + objAuthenticationInfo.access_token);
                req1.setHeader('Content-Type','application/json');
                req1.setMethod('POST');
                req1.setBody(requestBody);
                req1.setEndpoint(endP);
                if (LOG_THIS_CLASS) System.debug('end point : ' + req1.getEndpoint());
                if (LOG_THIS_CLASS) System.debug('end point : ' + req1.getBody());
                HttpResponse res1 = http2.send(req1);
            }
        }

And in the target org, I just do a simple function to insert the parsed Accounts:

@RestResource(urlmapping = '/getAccountData/*')
global  class accountRestService {

    PRIVATE STATIC FINAL BOOLEAN LOG_THIS_CLASS = TRUE;

    global class requestBody {
        global List<Account> accounts;
   }

    @httpPost
    global static List<Account> populateAccountObject(accountRestService.requestBody req){
        if (LOG_THIS_CLASS) System.debug('the request in populateAccountObject.. : ' + req);
        insert req.accounts;
        return req.accounts;
    }
}

To me, it only looks as though there's a problem when inserting the records before doing the callout as i tried in the Anonymous window. Any help pls. thx

Edit: Actually i get the following error in the target org:

Insert field: First exception on row 0 with id 00158000004kohAAE; first error: INVALID_FIELD_FOR_INSERT_UPDATE, cannot specify Id in an insert call:[Id]

Answer 1

It appears to me that based on what you know works, you'd need to do something like this in your execute method:

List<Account> accList = new List<Account>();
for( scope Account a:sObject){ 
   accList.add(a);
}

submitDataToTargetOrg.submitDataUsingRest(accList);

In essence, for the scope, you've not cast the list of sObjects to Accounts yet in your previous code.

Answer 2

actually, all i had to do was change the logic a bit in my target org to create a new account i.e. :

@httpPost
global static List<Account> populateAccountObject(accountRestService.requestBody req){
    List<Account> accountsToInsert = new List<Account>();
    Account newAccount;
    for(Account acc : req.accounts){
        newAccount = new Account(Name = acc.Name, Phone = acc.Phone);
        accountsToInsert.add(newAccount);
    }
    insert accountsToInsert;
    return accountsToInsert;
}

}