On Dec 12, 2012, at 10:07 AM, Peter Bunyan wrote: > Much like FormAlchemy, I am trying to update my model from a post in a > generic manner. I'd like to find out if an Attribute(InstrumentedAttribute) > or its associated ColumnProperty is read-only. (please excuse ridiculous > example) > > class Foo(Base): > id = Column(Integer, primary_key=True) > name = Column(String) > title = column_property( > select([func.UPPER(name)]).\ > where(id==id) > ) > > Although setting 'title' will not cause an insert or update in the db > transaction, as it is a column_property, it will be settable. I'd like to not > set the attribute by using class_mapper(Foo).iterate_properties and being > able to determine that it was read_only. I do not ask lightly. I've read > extensively and looked through the source code and come up blank. I also > acknowledge that I wrote the model so I know it's read only - but I'd rather > be lazy and get my update to do the work - after all, that is why I'm using > such an excellent ORM.
the column_property has a .columns collection, of which it is usually just columns[0]. If columns[0] is present in the mapped table, the ORM will write to it; otherwise not. So : mapper = class_mapper(Foo) table = mapper.local_table property = Foo.name.property expression = property.columns[0] is_a_regular_mapped_column = table.c.contains_column(expression) > > > > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To view this discussion on the web visit > https://groups.google.com/d/msg/sqlalchemy/-/kFNDPpm3J9EJ. > To post to this group, send email to sqlalchemy@googlegroups.com. > To unsubscribe from this group, send email to > sqlalchemy+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/sqlalchemy?hl=en. -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
