[Sqlalchemy-tickets] Issue #3034: Use my own bindparam for Query.limit() (zzzeek/sqlalchemy)

[Dobes V. <iss...@bi...>]

New issue 3034: Use my own bindparam for Query.limit()
https://bitbucket.org/zzzeek/sqlalchemy/issue/3034/use-my-own-bindparam-for-querylimit

Dobes Vandermeer:

I am trying to use the "baked query" pattern to reduce the time spent generating SQL, which currently is quite significant for our app.

One thing I can't seem to parameterize using a bindparam, however, is the limit on the query.

Although in #805 the limit was changed into a bindparam, this doesn't allow me to provide my own bindparam but rather always creates its own bindparam, assuming the limit I procide is a number already.

I think that if the places where currently it wraps a numeric limit into a bindparam using sql.literal() it would also check if limit was already a bindparam then it would be good.

Here's an example that can be pasted into the test suite:

```
#!python
    def test_select_with_bindparam_limit(self):
        """Does a query allow bindparam for the limit?"""
        sess = self._downgrade_fixture()
        users = []

        def go():
            users[:] = sess.query(self.classes.User)\
                .order_by(self.classes.User.id)\
                .limit(sa.bindparam('n'))\
                .params(n=10)\
                .all()
        self.assert_sql_count(testing.db, go, 2)
```