Hello. This is great! Unfortunately it does not work for me.
First, the "cursor_execute" event does not exist (at least in SA 0.7.X). I found "before_cursor_execute" which has equivalent signature. I debugged it and: * My callback function is successfully registered. * It is called for statements like DROP TABLE, CREATE TABLE and also for each select from a pg tables (I use postgres). * However, it is NOT called for ANY q.all() or foo.bar where both emit SELECT statements. Note that when these calls are made, the callback function that worked so far is still registered... Do you have any idea what could be wrong? Thank you, Ladislav Lenart On 26.9.2012 01:37, Michael Bayer wrote: > pretty much what I use for that is an event listener for SQL, which > logs/doesn't log based on external state. We have kind of a crufty one in > the test suite (see assertsql.py and testing.py->assert_sql_count). > > you can do it like this: > > emitters = set() > @event.listens_for(Engine, "cursor_execute") > def cursor_execute(conn, cursor, statement, parameters, > context, executemany): > for emit in emitters: > emit(statement) > > def assert_no_sql(fn): > def run(*arg, **kw): > def raise_(statement): > assert False, "SQL %s was emitted!" % statement > emitters.add(raise_) > try: > return fn(*arg, **kw) > finally: > emitters.discard(raise_) > > return run > > def test_my_thing(self): > obj = sess.query(Foo).get(1) > @assert_no_sql > def go(): > obj.related_items > go() > > or you can use a context manager, then its like "with assert_no_sql(): ...". > > > On Sep 25, 2012, at 1:59 PM, Ladislav Lenart wrote: > >> Hello. >> >> I would like to detect when an access to a mapped slot issues a SQL query. Is >> that possible with events? Where should I look? >> >> I want to unit-test that a query correctly preloads everything I need: >> >> def some_test(self): >> q = ... >> rows = q.all() >> print "#### Should not emit any SQL from here on ####" >> for each in rows: >> print each.a.b.c.d # Assert this does not emit any SQL >> >> I currently "test this manually" by looking at the output and see that no SQL >> communication was printed after the line "#### ... ####" (db engine is >> started >> with echo=True). >> >> >> Thank you, >> >> Ladislav Lenart >> >> -- >> You received this message because you are subscribed to the Google Groups >> "sqlalchemy" group. >> To post to this group, send email to sqlalchemy@googlegroups.com. >> To unsubscribe from this group, send email to >> sqlalchemy+unsubscr...@googlegroups.com. >> For more options, visit this group at >> http://groups.google.com/group/sqlalchemy?hl=en. >> > -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
