How to evaluate multiple child records in order to update a parent's status

Question

I have a sample request (header) table and product information (details). What I'm trying to do is after a product is shipped, an integration writes to the child record(s) and updates a field called: ship date actual with a date for when the product has been shipped. After all the child records have been marked with a ship date- the system should then update the parent status to Shipped. Otherwise, if there are child records not yet marked with a ship date- then keep the header status as it is: approved. I'm new to this- (I know, terribly obvious).

Parent Table: Sample_Request_Account_Information__c

Child Table: Sample_Request_Product_Information__c

Here is my apex code: I tried to look at an example which was posted on this forum to try my best to get this to work:

Apex Class: /** Updates the status field on Sample Request Account Information*/

public with sharing class childTriggerHandler {
   public void UpdateFields(List< Sample_Request_Product_Information__c > newList) 
   {
        List< Sample_Request_Account_Information__c > updateList = new List< Sample_Request_Account_Information__c >();
        Map<id,List< Sample_Request_Product_Information__c >> mapParentIDAndChild = new Map<id,List< Sample_Request_Product_Information__c >>();
        boolean flag;
        set<Id> parentTrue = new set<Id>();
        for(Sample_Request_Product_Information__c objChild : newList) {
            parentTrue.add(objChild.(Sample_Request_Account_Information__c));
        }
        for(Sample_Request_Product_Information__c objChild : [select id , Ship_Date_Actual__c, Sample_Request_Account_Information__c from Sample_Request_Product_Information__c where Sample_Request_Account_Information__c IN: parentTrue] ){
            system.debug('<<<<<<objChild '+objChild );
            if(mapParentIDAndChild.containsKey(objChild.Sample_Request_Account_Information__c)) {
                system.debug('<<<<<<in if 1st ');
                mapParentIDAndChild.get(objChild.(Sample_Request_Account_Information__c).add(objChild));
                system.debug('<<<<<<in if 1st mapParentIDAndChild '+mapParentIDAndChild);
            } else {
                system.debug('<<<<<<in else 1st ');
                mapParentIDAndChild.put(objChild.Sample_Request_Account_Information__c,new List< Sample_Request_Product_Information__c >{objChild});
                system.debug('<<<<<<in else 1st mapParentIDAndChild '+mapParentIDAndChild);
            }
        }
        for(Id objId : mapParentIDAndChild.keySet()) {
            flag = true;
            for(Sample_Request_Product_Information__c objChild : mapParentIDAndChild.get(objId)) {
                if(objChild.Ship_Date_Actual__c !==''){
                    flag = true;
                    break;
                }
            }
            if(flag == true) {
                updateList.add(new Sample_Request_Account_Information__c (Id = objId , Status__c = 'Shipped'));
            } else {
                updateList.add(new Sample_Request_Account_Information__c (Id = objId , Status__c = 'Approved'));
            }
        }
        if(!updateList.isEmpty()) {
            update updateList;
        }
    }// end of UpdateFields
}// end of childTriggerHandler

Answer 1

Alternative solution (no code)

1. Add two RSF fields on Parent: CountChildren__c, CountShippedChildren
2. Use a workflow/process builder that compares when both are equal and then updates Parent with header field

Usual caveats about RSF apply (no cross object formula references, no reference to formula fields with TODAY() or other relative dates

Answer 2

I could see few issues with the code

1. There shouldn't be ( after the dot notation. So change

   parentTrue.add(objChild.(Sample_Request_Account_Information__c));
   

to

parentTrue.add(objChild.Sample_Request_Account_Information__c);

2. You comparison operator is wrong. It should be != than !== and also you can't compare Date with String. So compare the date with NULL instead of '' which is string.

3. flag = true will always be true and update the parent status to 'Shipped' even all of child's ship date is null. So modify it as

   flag = true;
   for(Sample_Request_Product_Information__c objChild : mapParentIDAndChild.get(objId)) {
       if(objChild.Ship_Date_Actual__c == NULL){
           flag = false;
           break;
       }
   }
   

Hope it helps.