[sqlalchemy] Re: Creating Oracle Triggers on Table Create
On Aug 19, 2008, at 1:59 PM, Gerrat wrote:
Is there a way to easily hook into the table creation mechanism so
that whenever a Sequence was specified as part of a Column definition,
a similiar trigger could be inserted (substituting some names
obviously)? I know I can manually issue the DDL after-the-fact for
each table create, but would prefer it be more implicit.
I'm assuming that you mean you're already familiar with the DDL()
construct, which is documented at:
http://www.sqlalchemy.org/docs/05/sqlalchemy_schema.html#docstrings_sqlalchemy.schema_DDL
So the next step is to create your own Table function along the lines
of:
from sqlalchemy.schema import Table as _Table, Sequence, DDL
def Table(name, meta, *args, **kw):
t = _Table(name, meta, *args, **kw)
for c in t.c:
if c.default and isinstance(c.default, Sequence):
DDL(your per-sequence DDL
here).execute_at('after-create', t)
return t
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[sqlalchemy] Re: Creating Oracle Triggers on Table Create
On Aug 19, 2:11 pm, Michael Bayer [EMAIL PROTECTED] wrote:
On Aug 19, 2008, at 1:59 PM, Gerrat wrote:
Is there a way to easily hook into the table creation mechanism so
that whenever a Sequence was specified as part of a Column definition,
a similiar trigger could be inserted (substituting some names
obviously)? I know I can manually issue the DDL after-the-fact for
each table create, but would prefer it be more implicit.
I'm assuming that you mean you're already familiar with the DDL()
construct, which is documented at:
http://www.sqlalchemy.org/docs/05/sqlalchemy_schema.html#docstrings_s...
So the next step is to create your own Table function along the lines
of:
from sqlalchemy.schema import Table as _Table, Sequence, DDL
def Table(name, meta, *args, **kw):
t = _Table(name, meta, *args, **kw)
for c in t.c:
if c.default and isinstance(c.default, Sequence):
DDL(your per-sequence DDL
here).execute_at('after-create', t)
return t
Thanks for the super-quick response, Michael.
That's exactly what I was looking for!
...not sure where my head was at...didn't think of just browsing the
sources to look at the Table class. Pretty straight forward - thanks
again!
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[sqlalchemy] Re: Creating Oracle Triggers on Table Create
On Aug 19, 2008, at 5:08 PM, Gerrat wrote:
This doesn't quite work:
the DDL class (well, the method '_TextClause' in the module
'expression' actually) parses out any sql containing a ':' (colon) as
if it were a bind variable.
Althouth the documentation says: SQL bind parameters are not
available in DDL statements, it still looks for anything that
resembles a bind variable, then binds these variables to the None
value. Sqlalchemy then sends these invalid bind variables off to the
database with the sql.
I get an error back from the database with my trigger sql text,
followed by {'new':None, 'old':None}.
The special keywords in Oracle ':new', and ':old', aren't actually
bind variables when used in PL/SQL.
Any ideas for a workaround?
I'm using version 0.5.0beta3-py2.5
the colon can be escaped using a backslash, i.e. \: .
Maybe it would be a good idea for DDL() to construct _Text() with a
flag to disable bind parameter matching.
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