Let's say I have the following model with a synonym for the "code"
column that is called "value":
from elixir import *
from sqlalchemy import create_engine, and_
engine = create_engine('sqlite:///:memory:', echo=True)
metadata.bind = engine
class Node(Entity):
using_options(tablename='nodes')
parent = ManyToOne('Node')
code = Field(String(20), unique=True)
name = Field(String(50))
lft = Field(Integer)
rgt = Field(Integer)
value = Synonym('code')
setup_all(True)
n2 = Node.table.alias('n2')
query = Node.query.filter(and_(n2.c.code == 'xxx',
n2.c.lft <= Node.c.lft,
n2.c.rgt >= Node.c.rgt))
The query above works fine. However, if I want the query to refer to
"value" instead of "code", I just couldn't find a clean way to do so.
Here's one workaround that retrieves the actual column name from the
synonym and then uses it in the query:
prop = Node.mapper.get_property('value')
if hasattr(prop, 'name'):
colname = prop.name
else:
colname = prop.key
query = Node.query.filter(and_(n2.c[colname] == 'xxx',
n2.c.lft <= Node.c.lft,
n2.c.rgt >= Node.c.rgt))
Another workaround is to modify table.c so that it is possible to use
table.c.value:
Group.c['value'] = Group.c.code
query = Node.query.filter(and_(n2.c.value == 'xxx',
n2.c.lft <= Node.c.lft,
n2.c.rgt >= Node.c.rgt))
What I prefer is to make it possible to alias the Entity, and then use
it directly in query and have it resolves the synonym transparently,
i.e.:
n2 = Node.alias('n2')
query = Node.query.filter(and_(n2.value == 'xxx',
n2.lft <= Node.lft,
n2.rgt >= Node.rgt))
Which way do you think is the cleanest? Is there any other workaround?
Regards,
Yap
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