sqlalchemy - How to select count from a union query

Question

My goal is that I have two tables, each describes a relationship between a user and either a "team" or "company"

If there are any rows that says "admin" in the tables for the userid, then I want to know that, otherwise if no rows then i need to know that as well.

What I have so far is as follows (UserTeamLink and UserCompanyLink) are Orm tabels.

obj = UserTeamLink
q1 = session.query(func.count(obj.type).label("cnt")).filter(obj.type == 'admin').filter(obj.user_id == id) ; str(q1) ; q1.all()
obj = UserCompanyLink
q2 = session.query(func.count(obj.type).label("cnt")).filter(obj.type == 'admin').filter(obj.user_id == id) ; str(q2) ; q2.all()

my_union = q1.union_all(q2)
query = select([func.sum(my_union.c.cnt).label("total_cnt")], from_obj=my_union)
query.all()

however, the line "query = select([func.sum(my_union.c.cnt).label("total_cnt")], from_obj=my_union)" breaks with:

AttributeError: 'BaseQuery' object has no attribute 'c'

The entire output is as follows:

>>> obj = UserTeamLink
>>> q1 = session.query(func.count(obj.type).label("cnt")).filter(obj.type == 'admin').filter(obj.user_id == id) ; str(q1) ; q1.all()
'SELECT count(user_team.type) AS cnt \nFROM user_team \nWHERE user_team.type = :type_1 AND user_team.user_id = :user_id_1'
[(0L,)]
>>> obj = UserCompanyLink
>>> q2 = session.query(func.count(obj.type).label("cnt")).filter(obj.type == 'admin').filter(obj.user_id == id) ; str(q2) ; q2.all()
'SELECT count(user_company.type) AS cnt \nFROM user_company \nWHERE user_company.type = :type_1 AND user_company.user_id = :user_id_1'
[(0L,)]
>>> 
>>> my_union = q1.union_all(q2)
>>> query = select([func.sum(my_union.c.cnt).label("total_cnt")], from_obj=my_union)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'BaseQuery' object has no attribute 'c'

Is there a way to fix this?

In summary what I'm attempting to do is select counts from both tables, then union into another table and then add them.

Thank you.

Answer 1

You need to use my_union as subquery

my_union = q1.union_all(q2).subquery()
query = select([func.sum(my_union.c.cnt).label("total_cnt")], from_obj=my_union)

Answer 2

Here's my own problem solved, I used a slightly different approach than @rmn's however I think both should work:

    q_union = q1.union_all(q2)
    q_union_cnt = db.session.query(func.sum(q_union.subquery().columns.cnt).label("total_cnt"))
    admin_points = q_union_cnt.scalar()