Django ORM groupby

Question

row_1(PK)	row_2	row_3
1	row	one
2	row	two
3	row	three

Data from my database table looks like the above table.

SELECT
   GROUP_CONCAT(row_3)
FROM table_
WHERE row_2 = 'row'
GROUP BY row_2;

My Django query to achieve above mysql query

table_.objects.filter(
    row_2='row'
).annotate(
    val=GroupConcat('row_3', '')
).values('val')

When converting the above ORM to raw mysql query, it's grouing by primary key (row_1). I want to group by 'row_2' column .

Answer 1

You need to use .order_by(…) ^[Django-doc], yes I know that sounds strange, so:

table_.objects.filter(row2='row').values('row2').annotate(
    val=GroupConcat('row3', '')
).order_by('row2')

But here it looks like you are actually making an aggregate, since only one sort of value for row2 is picked due to the filtering, so grouping by that value is not necessary. You can use .aggregate(…) ^[Django-doc] in that case:

table_.objects.filter(row2='row').aggregate(val=GroupConcat('row3', ''))