the .any() and .has() operators use a correlated EXISTS query, so no JOIN is
needed (I'd probably guess LINQ does the same, actually).
If you're trying to say something like Job.dependencies, then
"Job.dependencies" is a relationship() in that case, if it's many-to-many that
doesn't really matter, the any() operator knows how to work with many-to-many
that is correctly configured.
Here's a complete example:
from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.ext.declarative import declarative_base, declared_attr
from sqlalchemy import event
Base = declarative_base()
# many-to-many association table
JobDependency = Table('job_dependency', Base.metadata,
Column('jobId', Integer, ForeignKey('job.id'), primary_key=True),
Column('dependsOnJobId', Integer, ForeignKey('job.id'), primary_key=True)
)
class Job(Base):
__tablename__ = 'job'
id = Column(Integer, primary_key=True)
status = Column(String(20), default='queued', nullable=False)
dependencies = relationship(lambda: Job,
secondary=JobDependency,
primaryjoin=id==JobDependency.c.jobId,
secondaryjoin=id==JobDependency.c.dependsOnJobId,
backref='dependencyOf')
e = create_engine("sqlite://", echo='debug')
Base.metadata.create_all(e)
s = Session(e)
j1 = Job(status='queued', dependencies=[Job(status='done'), Job(status='done')])
j2 = Job(status='queued', dependencies=[Job(status='inprogress')])
s.add_all([j1, j2])
jobs = s.query(Job).\
filter(Job.status == 'queued').\
filter(~Job.dependencies.any(Job.status != 'done')).all()
assert jobs == [j1]
On Apr 18, 2014, at 5:20 AM, Maik Riechert <[email protected]> wrote:
>
> query(Job).filter(Job.status ==
> 'queued').filter(~Job.dependencies.any(Dependency.status != 'done'))
>
>
> One more thing. Dependency doesn't exist as a class. Job.dependencies is a
> many-to-many association. That's why you probably have to use aliases to
> refer to the status of the dependency Job. I just couldn't get it to work
> though. The basic model:
>
> # many-to-many association table
> JobDependency = Table('job_dependency', Base.metadata,
> Column('jobId', Integer, ForeignKey('job.id'), primary_key=True),
> Column('dependsOnJobId', Integer, ForeignKey('job.id'), primary_key=True)
> )
>
> class Job(Base):
> __tablename__ = 'job'
>
> id = Column(Integer, primary_key=True)
> status = Column(String(20), default='queued', nullable=False)
>
> dependencies = relationship(lambda: Job,
> secondary=JobDependency,
> primaryjoin=id==JobDependency.c.jobId,
>
> secondaryjoin=id==JobDependency.c.dependsOnJobId,
> backref='dependencyOf')
>
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