[Sqlalchemy-tickets] Issue #4337: aggregate_order_by doesn't accept multiple columns as order_by argument (zzzeek/sqlalchemy)

[Pierre C. <iss...@bi...>]

New issue 4337: aggregate_order_by  doesn't accept multiple columns as order_by argument
https://bitbucket.org/zzzeek/sqlalchemy/issues/4337/aggregate_order_by-doesnt-accept-multiple

Pierre Collet:

Hello,

The [aggregate_order_by](http://docs.sqlalchemy.org/en/latest/dialects/postgresql.html#sqlalchemy.dialects.postgresql.aggregate_order_by) function currently take only 2 arguments (target and order_by) while PostgreSQL (9.6 in my case) totally accept multiple columns in the ORDER BY clause.


For instance:
```
#!sql

SELECT array_agg(status ORDER BY pk_col1, pk_col2)
FROM table_with_pk_on_two_columns
GROUP BY  col_x;
```

As Mike Bayer emphasized ([here](https://groups.google.com/forum/#!topic/sqlalchemy/A_jfE8hOQHQ) ), it is possible to use a sqlalchemy.sql.expression.ClauseList to specified multiple columns as order_by argument.

Example:

```
#!python

from sqlalchemy.dialects.postgresql import aggregate_order_by 
from sqlalchemy import column 
from sqlalchemy.dialects import postgresql 
from sqlalchemy.sql.expression import ClauseList 

elem = aggregate_order_by(column('a'), ClauseList(column('b').asc(), column('c').desc())) 

print(elem.compile(dialect=postgresql.dialect())) 
a ORDER BY b ASC, c DESC 
```


Still, it would be convenient to make the order_by argument a list (*order_by).


Pierre.