On Apr 25, 2010, at 7:46 PM, Michael Bayer wrote:
>
> You can acheive mostly the result you want using a custom SQL expression
> construct, in conjunction with sqlalchemy.ext.compiler. The construct would
> peek into a context-specific dictionary for its contents at compile time and
> forward onto it's corresponding construct. You'd stick the dictionary on
> the the outermost containing construct, which you can then grab from the
> compiler instance.
here's that:
from sqlalchemy import *
from sqlalchemy.sql.expression import ColumnElement
from sqlalchemy.ext.compiler import compiles
def with_sql_tokens(element, **tokens):
element._sql_tokens = tokens
return element
class SQLToken(ColumnElement):
def __init__(self, name):
self.name = name
@compiles(SQLToken)
def visit_sql_token(element, compiler, **kw):
value = compiler.statement._sql_tokens[element.name]
return compiler.process(value)
if __name__ == '__main__':
from sqlalchemy.sql import table, column
t1 = table('sometable', column('c1'), column('c2'))
s1 = select([t1]).where(SQLToken('whereclause'))
print with_sql_tokens(s1, whereclause=or_(t1.c.c1=='foo', t1.c.c2=='bar'))
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