Hello, I am actually working on my previous post about the OrderedDict and the None values and I met new problems and new questions. I didn't found answers on the Internet, so here I am !
As explained in the official documentation (or in the following topic : https://groups.google.com/forum/#!msg/sqlalchemy/2dVQTvzmi84/8J8lGpLfw4EJ), using backref or back_populates on relationship "sets up the "synchronization" of the two directions, which consists of an event that performs the complimentary set/append operation when an append/set occurs on the other side". Here is the example gived by the topic previously mentionned : p = Parent('parent1') c = Child('child1') c.parent = p p.children.append(c) *p's children will contain c twice.* In deed, the "c.parent = p" operation results in the "append" on the other side, and vice versa. In my case, I'm working on an existing project which contains a lot of classes and the methods are already designed in order to add the objects on the two sides. It is so because the program is using Pickle to persist everything (my objectiv is to replace it by SQLAlchemy). Of course, I could adapt the code but it will be a lot of work and I don't like the idea that my structures are automatically synchronized without explicit declarations. Furthermore, what will happen if I decide, one day, to stop using SQLAlchemy ? My code would be too dependent on the fonctionnalities provided by SQLAlchemy. So, my questions are : 1) Is it feasible to avoid to use backref or back_populates ? Would it be a bad idea to work without these fonctionnalities ? Will I face for example inconsistent state of the program ? 2) Is it possible to use back_populates and allow SQLAlchemy to detect that it should not append something which was already inserted ? Thank you very much ! Regards, Sven -- SQLAlchemy - The Python SQL Toolkit and Object Relational Mapper http://www.sqlalchemy.org/ To post example code, please provide an MCVE: Minimal, Complete, and Verifiable Example. See http://stackoverflow.com/help/mcve for a full description. --- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at https://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
