[Sqlalchemy-tickets] Issue #3353: combination of and_() and or_() produces unexpected sql output (zzzeek/sqlalchemy)

[petergrace <iss...@bi...>]

New issue 3353: combination of and_() and or_() produces unexpected sql output
https://bitbucket.org/zzzeek/sqlalchemy/issue/3353/combination-of-and_-and-or_-produces

petergrace:

For the given filter spec, the sql generated does not match what I would expect to see:


```
#!python

.filter(or_( \
            and_(func.len(ExtendedCDR.Source) > 6, ExtendedCDR.DestinationContext=='ael-outbound-dial'), \
            and_(func.len(ExtendedCDR.Destination)>6,ExtendedCDR.DestinationContext=='ael-std-extension') \
        ) \

```
This produces:


```
#!sql

	(len(cdr_extended.[Source]) > ? AND 
	cdr_extended.[DestinationContext] = ? OR 
        len(cdr_extended.[Destination]) > ? AND 
	cdr_extended.[DestinationContext] = ?) 
```
Note only a single set of parantheses wrapping the logic, whereas I would expect to see:


```
#!sql

(
(len(cdr_extended.[Source]) > ? AND cdr_extended.[DestinationContext] = ?)
OR 
(len(cdr_extended.[Destination]) > ? AND cdr_extended.[DestinationContext] = ?)
)

```

If I am misunderstanding how and_ and or_ are supposed to work together, can you set me straight, or alternatively let me know how I can cause sqlalchemy to emit the query with the proper order of operations?