Two inserts in one trigger casues the second insert to fail

Question

I have a triggerHandler on the Opportunity object which inserts other objects on afterInsert if it meets the criteria (Opportunity Line Item and Payment). The objects are added to a list before inserting but when the first list is inserted the next list is emptied/nulled so nothing is being inserted on the next list.

The instantiation of the lists looks like this:

static List<Membership__c> membershipsToUpdate;
static List<Case> casesToUpdate;
static List<OpportunityLineItem> oppItemsToInsert;
static List<npe01__OppPayment__c> paymentsToInsert;

public TRG_OpportunityHandler(){
    membershipsToUpdate = new List<Membership__c>();
    casesToUpdate = new List<Case>();
    oppItemsToInsert = new List<OpportunityLineItem>();
    paymentsToInsert = new List<npe01__OppPayment__c>();
}

And the inserts look like this:

  if(paymentsToInsert.size() > 0) {
        insert paymentsToInsert;
    }
    if(oppItemsToInsert.size() > 0) {
        insert oppItemsToInsert;
    }
    if(membershipsToUpdate.size() > 0) {
        update membershipsToUpdate;
    }
    if(casesToUpdate.size() > 0 ){
        update casesToUpdate;
    }

If I switch place and insert oppItemsToInsert before paymentsToInsert then oppItems are inserted but not payments. Is it really not possible to do 2 DML transactions in one trigger? How else can I do this?

Answer 1

Moving the instantiation from the constructor of the handler to inside the afterInsert trigger method solved it. Since the trigger was firing again with an update it reinstatiated the lists and nulled them: http://prntscr.com/oxnuhp