On Nov 7, 2007, at 10:23 AM, Werner F. Bruhin wrote:
>
> How can I define a column in the table as read-only?
>
> I have some "computed by" columns, e.g.:
> consumedvalue computed by (quantity*unitprice)
>
> These columns can not be updated, otherwise I get the following
> exception:
> ProgrammingError: (ProgrammingError) (-151, 'isc_dsql_prepare: \n
> attempted update of read-only column')
>
read-only behavior is a class-level thing, so something like this:
class MyClass(object):
def mycol(self):
return self._mycol
mycol = property(mycol)
mapper(MyClass, mytable, properties={
'_mycol':mytable.c.mycol,
'mycol':synonym('_mycol')
})
Theres a ticket in trac which will make the above configuration
slightly less verbose in a future release.
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