Check if Parent record exists using parent's External Id before inserting child

Question

I have a child__c object that has a lookup relationship to Parent__c. Each have an ExternalId__c field in them.

I am trying to create this relationship when inserting a child record.

    List<Child__c> childList = new List<Child__c>();
    for(wrapperObj wr : wrpList){
    Child__c c = new Child__c();
    string parentExtId = wr.Field1 + wr.Field2;
    Parent__c prnt = new Parent__c(External_ID__c = parentExtId);
    c.External_Id__c = wr.Field3 + wr.Field4;
    c.Parent__r = prnt;
    childList.add(c);
    }

upsert childList External_Id__c;

Using this approach I sometime get an error when a Parent doesn't exists with the same parent external Id combination i.e. wr.Field1 + wr.Field2. Error - INVALID_FIELD, Foreign key external ID:XXX not found for field External_ID__c in entity Parent__c .Is there a way to mitigate this error. As of now I do not want to do a SOQL on Parent.

Answer 1

One option available is to use the Database.upsert() method with the allOrNone parameter set false and then look for errors in the results. This is helpful if partial success is acceptable.

Database.UpsertResult[] results = Database.upsert(childList, External_Id__c, false);

for (Database.UpsertResult result : results) {

    if (result.isSuccess()) {
        // child upserted without error

    } else {
        // child could not be upserted
        Database.Error[] errorList = result.getErrors();

        // do something with the error list to inform the
        // caller of a partial failure
    }
}