On Tue, Jun 26, 2018 at 3:56 PM, Victor Reichert <victor.reich...@apptactoe.com> wrote: > Hi, > > I have a class like: > > class SQLClass(db): > > json_field = Column(sqlalchemy.dialects.postgresql.JSONB) > > I'm doing something like: > > session.add( > SQLClass(json_field = dict( > key = [value1] > ) > )) > > session.commit() > > slq_class_obj = session.query(SQLClass).first() > > new_dict = slq_class_obj.json_field > > new_dict['key'].append(value2) > > slq_class_obj. json_field = new_dict > > print(slq_class_obj. json_field) # looks OK > > session.commt() > > print(slq_class_obj. json_field) # I just get [value1] > > The changes I made to json field (new_dict) were not persisted. However, if > just change the json_field to be an empty dict that is persisted. > > I know there are some issues with mutation and the JSON data type, but I > thought since I was setting the field value rather than just mutating the > dict in place the mutation would be tracked.
you are not creating a new dictionary above, just assigning the attribute to itself. that's just in-place mutation. the attribute system might log this as "changed" but when it goes to compare what it loaded from the database with what the value is now, it will see they are equal since they are the same object, and no net change. if your jsonb is storing just a dictionary, place mutabledict around it and your problem is solved. http://docs.sqlalchemy.org/en/latest/orm/extensions/mutable.html?highlight=mutabledict#sqlalchemy.ext.mutable.MutableDict > > Why is setting the field to an empty dict persisted while my change is not? > Any general advice on handling JSON and mutation would also be welcome. > > Thank you for your help! > > ~Victor > > -- > 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. -- 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.
