I solved everything by overriding against()
_DDL_MATCHER = re.compile(ur"\$\{(_\w+)\:{0,1}([^\}]*)\}")
class CustomDDL(DDL):
def __init__(self, statement, on=None, context=None, bind=None):
super(CustomDDL, self).__init__(statement, on, context, bind)
def against(self, target):
global _DDL_MATCHER
def repl(match):
func = match.group(1)
args = match.group(2)
return getattr(self, func)(target, args)
return _DDL_MATCHER.sub(repl, self.statement);
This works for me.
I'm getting engine from target.metadata.bind and I hope that it's correct way.
On Wed, Sep 1, 2010 at 2:15 AM, Petr Kobalíček <kobalicek.p...@gmail.com> wrote:
> Hi,
>
> I have problem to understand which way should be used to write custom
> DDL class. I'm generating some stored procedures for my tables. The
> procedures are very similar and I'd like to use some generic way. Now
> I'm nearly done, but I need some way how to extract some information
> from table to use it in my DDL.
>
> I discovered that for this I need the engine where DDL runs.
>
> My custom class may look like this:
>
> class CustomDDL(DDL):
> def against(self, target):
> # Is this the method I should generate the DDL? How can I access
> engine from here?
> self.target = target
>
> There is also possibility to create a __call__ method where the engine
> is, but I'm not sure if this is the right place.
>
> So my questions:
>
> - which method I should override to make my custom DDL substitution
> - do I need to base class on DDL or DDLElement? I can create my own,
> but I'm not sure if I can add it.
>
>
>
> Currently I'm using something like this to inject some triggers/functions:
>
> _DDL_MATCHER = re.compile(ur"\$\{(_\w+)\:{0,1}([^\}]*)\}")
>
> class CustomDDL(object):
> def __init__(self, event, ddl):
> self.event = event
> self.ddl = ddl
>
> def inject(self, table):
> DDL(self.compile(table)).execute_at(self.event, table)
>
> def compile(self, table):
> global _DDL_MATCHER
> def repl(match):
> func = match.group(1)
> args = match.group(2)
> return getattr(self, func)(table, args)
> return _DDL_MATCHER.sub(repl, self.ddl);
>
> def _TABLE(self, table, args):
> return table.name + args
>
> def _PREPARE_DECLARATION(self, table, args):
> result = u""
> if hasattr(table, "area"):
> for column in table.area:
> #result += u"condition_" + unicode(column.name) + u" " + \
> # unicode(column.type.get_dbapi_type(engine.dialect.dbapi)) + u"; "
> pass
> return result
>
> def _PREPARE_CONDITION(self, table, args):
> return ""
>
> def _WHERE(self, table, args):
> if args:
> return u"WHERE " + args
> else:
> return u""
>
> This works for me, except I need to access the engine.
>
> Thanks for any info about this
>
> Best regards
> Petr
>
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