Batchable Class from a List, not from a query

Question

Is it possible to run a batchable class from a List<sObject> that is passed into the constructor as opposed to generating a scope list from a query?

For example, I have a list of singleEmailMessage object, essentially composed emails ready to be sent like so: Messaging.sendEmail( email_list ); But since there is a limit of 10 emails per transaction and only so many emails within a given transaction, I need this to be batchable.

For now I have something very simple like this started but not sure where to go from here:

global class SendEmailBatch implements Database.Batchable<sObject> {
    public String query;
    public List<SingleEmailMessage> email_list;

    global SendEmailBatch(List<SingleEmailMessage> emails) {
        this.query = query;
        this.email_list = emails;
    }

    global Database.QueryLocator start(Database.BatchableContext bc) {
        return Database.getQueryLocator(query);
    }

    global void execute(Database.BatchableContext BC, list<Sobject> scope) {
        Messaging.sendEmail( email_list ); 
    }

    global void finish(Database.BatchableContext BC) {}
}

As you can see above I'm attempting to just bypass the default parameters but I'm not sure this is the best way, this is my very first batch class. My thought is I need this list in the scope variable in order for it to properly batch.

Any help you can provide to this question would be very helpful, thanks!

Answer 1

The below is an example of pattern that you need to follow to send bulk emails

List<Messaging.SingleEmailMessage> emails = new List<Messaging.SingleEmailMessage>();
 for(integer i = 0; i < 15; i++){
   Messaging.SingleEmailMessage email = new Messaging.SingleEmailMessage();
   email.setSubject('email '+i+' of 15');
   email.setToAddresses( new List<String>{'[email protected]'} );
   email.setPlainTextBody('this message was generated from apex');
   emails.add(email);
 }
  Messaging.sendEmail(emails);

For each of your scope element generate a Messaging.singleEmailMesssage and outside for loop fire the Messaging.sendEmail method

Also you can use custom iteratable documented below

https://www.salesforce.com/us/developer/docs/apexcode/Content/apex_classes_iterable.htm