Upsert List<SObject> With External Id And No "AllOrNothing" Fix

gistfile1.txt

public static List<Database.UpsertResult> upsertListSObjectsWithExternalIdNoAllOrNothingErrorExampleFix() {
        /* To resolve the System.TypeException: DML on generic List<SObject> only allowed for insert, update or delete"
           error, dynamically instantiate the List of SObject to a list of a concrete SObject type.
         */

        Account a = new Account(
            Name = 'Example Company',
            External_Id__c = 'ExampleCompany'
        );
        
        Schema.SObjectType objectType = a.getSobjectType();
        Schema.DescribeSObjectResult objectDescribe = objectType.getDescribe();
        String objectName = objectDescribe.getName();
        
        Type sObjectListType = Type.ForName('List<' + objectName + '>');
        
        List<SObject> records = (List<SObject>) sObjectListType.newInstance();
        
        records.add(a);
        
        Schema.SObjectField f = Account.Fields.External_Id__c;
        
        // Runs Successfully.
        return Database.Upsert(records, f);
    }