On Wed, Jan 3, 2018 at 1:18 PM, Tim Chen <timch...@gmail.com> wrote: > Let's say I'm using a uuid PK for my models with a ` server_default` set to > `gen_random_uuid()` (in PostgreSQL). Is there a way to ensure the > server_default value? I would like to catch any INSERT or UPDATE statements > that set the PK value and raise an error if possible.
Sure, I would use a before_cursor_execute() handler that does this. You can see the parameters and the statement coming in and raise an error if they have column values you don't want to see. http://docs.sqlalchemy.org/en/latest/core/events.html#sqlalchemy.events.ConnectionEvents.before_cursor_execute this is cleanest using some of the internal state of the context so here is a demo: from sqlalchemy import * from sqlalchemy.orm import * from sqlalchemy import event from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() class A(Base): __tablename__ = 'a' id = Column(Integer, primary_key=True) x = Column(Integer) e = create_engine("sqlite://", echo=True) @event.listens_for(e, "before_cursor_execute") def receive_before_cursor_execute(conn, cursor, statement, parameters, context, executemany): if context.isinsert: table = context.compiled.statement.table for col in table.primary_key: if col.key in context.compiled.binds: raise TypeError("no pk allowed!") Base.metadata.create_all(e) s = Session(e) s.add(A(x=5)) s.commit() # OK s.add(A(id=2, x=7)) s.commit() # not OK > > -- > 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.
