It is common (for us) to have tables with an identity column and that
column *not* be the primary key. I am dealing with this by querying
the system catalogs and caching the result within the table meta-data
object itself (probably a bad idea but doing it for expediency). The
system catalog query returns -- of course -- the database-level
identifier for the column with the identity property set. How do I
find out if the insert parameters have a value for the identity
column? I am using something like this which has a very evil look to
it:
if identity_column in [t.c[key].name for key in
self.compiled_parameters[0]]:
pjjH
if self.compiled.isinsert:
self.logger.debug('pre_exec for an
INSERT')
t = self.compiled.statement.table
if self._table_identity_column(t) is not None:
self.HAS_IDENTITY = True
# This returns the database-level name of the column
# Since the parameters may have different names (this
# will happen if a named parameter, 'key', was passed
# to the Column constructor), we need to project out
the names
identity_column = self._table_identity_column(t)
self.logger.debug([t.c[key].name for key in
self.compiled_parameters[0]])
if identity_column in [t.c[key].name for key in
self.compiled_parameters[0]]:
self.IDENTITY_INSERT = True
self.logger.debug('setting IDENTITY_INSERT ON FOR
%s' % (t))
# detect if the table has an identity column by direct query against
the system catalogs
def _table_identity_column(self, t):
"""Return the name of the this table's identity column"""
# negative caching
if not hasattr(t, '_identity_column'):
t._identity_column = None
s = sql.select([syscolumns.c.name],
from_obj=syscolumns.join(sysobjects))
s = s.where(sql.and_(sysobjects.c.name == t.name, sql.text
("(status & 128 = 128)")))
r = self.connection.execute(s).fetchone()
if r is not None:
t._identity_column = r[0]
return t._identity_column
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