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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