Add preserve_pkey argument which allows user to specify primary key for tables which do not auto populate.

Author: ptomasula

src/odm2datamodels/base.py

@@ -105,14 +105,32 @@ def read_query(self,
                 return df.to_dict()
             raise TypeError("Unknown output format")
 
-    def create_object(self, obj:object) -> Union[int, str]:
-        pkey_name = obj.get_pkey_name()
-        setattr(obj, pkey_name, None)
     def insert_query(self, objs:List[object]) -> None:
         with self.session_maker() as session:
             session.add_all(objs)
             session.commit()
 
+    def create_object(self, obj:object, preserve_pkey:bool=False) -> Union[int, str]:
+        """ Accepts an ORM mapped model and created a corresponding database record
+
+        Accepts on one of the ORM mapped models and creates the corresponding database 
+        record, returning the primary key of the newly created record.
+
+        Arguments:
+            obj:object - The ORM mapped model
+            preserve_pkey:bool - Default=False - flag indicating if the primary key for 
+                the object should be preserved. Avoid in general use cases where database has 
+                a serial that auto assigned primary key, however this can be set to True to
+                specify you own the primary key value.  
+
+        Returns:
+            primary key: Union[int, str]        
+
+        """
+        
+        if not perserve_pkey:
+            pkey_name = obj.get_pkey_name()
+            setattr(obj, pkey_name, None)
 
         with self.session_maker() as session:
             session.add(obj)