$A.getCallback error says property undefined

Question

Could someone explain what is happening within these lines in detail, as I am getting an error pointed to these lines. Also please advise on any fixes possible. thanks

approvePaymentRequest: function(component) {
        this.submitAction(component, "c.approvePaymentRequest");
      },
      submitAction: function(component, methodName) {
        component.set("v.disabled", true);
        this.enqueueAction(component, methodName, { paymentRequestId: component.get("v.paymentRequest.Id") },
          function() {
            var refreshComponentEvent = $A.get("e.c:refreshComponentEvent");
            refreshComponentEvent.setParams({ "event": "paymentRequestUpdated" });
            refreshComponentEvent.fire();
            component.find("recordLoader").reloadRecord(true);
            $A.get("e.force:refreshView").fire();
          },
          function() {
            component.set("v.disabled", false);
          }
        );
      },

APEX

  @AuraEnabled
  public static void approvePaymentRequest(Id paymentRequestId) {
    Payment_Request__c paymentRequest = [SELECT Id, Status__c, Coop_Campaign__c FROM Payment_Request__c WHERE Id = :paymentRequestId];
    paymentRequest.Approved_Date__c = Date.today();
    paymentRequest.Status__c = 'Approved';
    update paymentRequest;

    List<Coop_Campaign__c> coopCampaigns = [SELECT Id, Payment_Status__c FROM Coop_Campaign__c WHERE Id = :paymentRequest.Coop_Campaign__c AND (Payment_Status__c = 'Pending Finance Approval')];
    if (coopCampaigns.size() > 0) {
      Coop_Campaign__c coopCampaign = coopCampaigns[0];
      List<Payment_Request__c> paymentRequests = [SELECT Id FROM Payment_Request__c WHERE Coop_Campaign__c = :coopCampaign.Id AND (Status__c = 'Pending Finance Approval')];
      if (paymentRequests.size() == 0 && coopCampaign != null) {
        coopCampaign.Payment_Status__c = 'Approved';
        update coopCampaign;
      }
    }
  }

And here is the error message I get

Answer 1

component.find("recordLoader").reloadRecord(true);

In the above code, when you get the undefined error , you need to make sure that whichever variables throws undefined error, is assigned a value to it.

In this case, component.find("recordLoader")

recordLoader would normally be an assigned ID of what would probably be another aura component in the template of the JS file.

If you are not familiar with what might be going on I would suggest you take a look at Calling Component Methods.