CASE WHEN with ORM (SQLalchemy)

Question

I am using SQLAlchemy with the ORM paragdim. I don't manage to find a way to do a CASE WHEN instruction. I don't find info about this on the web. Is it possible ?

Accepted Answer

See sqlalchemy.sql.expression.case function and more examples on the documentation page. But it would look like this (verbatim from the documentation linked to):

```
case([(orderline.c.qty > 100, item.c.specialprice),
      (orderline.c.qty > 10, item.c.bulkprice)
    ], else_=item.c.regularprice)
case(value=emp.c.type, whens={
        'engineer': emp.c.salary * 1.1,
        'manager':  emp.c.salary * 3,
    })
```

edit-1: (answering the comment) Sure you can, see example below:

```
class User(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True, autoincrement=True)
    first_name = Column(String)
    last_name = Column(String)

xpr = case([(User.first_name != None, User.first_name + " " + User.last_name),],
        else_ = User.last_name).label("full_name")

qry = session.query(User.id, xpr)
for _usr in qry:
    print _usr.fullname
```

Also see Using a hybrid for an example of `case` used in the hybrid properties.

CASE WHEN with ORM (SQLalchemy)

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