not totally sure what you’re going for here as I think you’re looking at the problem using a different vocabulary. From the query you have at the bottom, it appears you’d want this:
for teacher in
session.query(Teacher).join(Teacher.aula).filter(Aula.nr_aula=='B2'):
print teacher.id, teacher.name
for aula in teacher.aula:
print aula.nr_aula
overall the best approach is to figure out what SQL represents the query you’re
trying to do, then we can express that using a Query.
On Nov 25, 2013, at 2:37 PM, mando <mandol...@gmail.com> wrote:
> Hi to all,
> I've copied ([1]) and rewrote some parts of this code [0] that is usefull for
> my project, where I need to reusing some tables as a child of many parents.
> In concrete I need something like this:
>
> Table_parent_1
>
> Table_parent_2
>
> Table_child_1
>
> Table_parent_1_to_child_1
>
> Table_parent_2_to_child_1
>
> And the following code do it!
>
> When I insert data into the tables all running properly, but if I want to
> make a query with a filter, the query return me all the records, and not only
> the record which I'm searching for.
>
> It's possible to make a direct query to all tables with a filter? Or is more
> usefull realize a class that embed the tables to make a direct query?
>
> Every suggestion will be helpful.
> Thanks in advance.
> Best regards.
>
> Luca
>
>
> [0]
> Link
>
> [1]
> from sqlalchemy import create_engine
> from sqlalchemy import Table, Column, Integer, String, ForeignKey, Sequence
> from sqlalchemy.ext.declarative import declarative_base
> from sqlalchemy.orm import sessionmaker, relationship
>
>
> Base = declarative_base()
>
>
> teachers_lessons = Table(
> "teachers_lessons",
> Base.metadata,
> Column("fk_teacher", Integer, ForeignKey("teachers.id")),
> Column("fk_lesson", Integer, ForeignKey("lessons.id")),
> )
>
> aula_lessons = Table(
> "aula_lessons",
> Base.metadata,
> Column("fk_teacher", Integer, ForeignKey("teachers.id")),
> Column("fk_aula", Integer, ForeignKey("aula.id")),
> )
>
> computer_aula = Table(
> "computer_aula",
> Base.metadata,
> Column("fk_computer", Integer, ForeignKey("computer.id")),
> Column("fk_aula", Integer, ForeignKey("aula.id")),
> )
>
> class Teacher(Base):
> __tablename__ = "teachers"
>
> id = Column("id", Integer, Sequence("teachers_id_seq"),
> primary_key=True)
> name = Column("name", String(50), nullable=False)
>
> lessons = relationship(
> "Lesson",
> backref="teachers",
> secondary=teachers_lessons
> )
>
> aula = relationship(
> "Aula",
> backref="teachers",
> secondary=aula_lessons
> )
>
> class Computer(Base):
> __tablename__ = "computer"
>
> id = Column("id", Integer, Sequence("computer_id_seq"),
> primary_key=True)
> pc_code = Column("pc_code", String(50), nullable=False)
>
> aula = relationship(
> "Aula",
> backref="computer",
> secondary=computer_aula
> )
>
>
> class Lesson(Base):
> __tablename__ = "lessons"
>
> id = Column("id", Integer, Sequence("lessons_id_seq"), primary_key=True)
> name = Column("name", String(50), nullable=False)
>
> class Aula(Base):
> __tablename__ = "aula"
>
> id = Column("id", Integer, Sequence("aula_id_seq"), primary_key=True)
> nr_aula = Column("nr_aula", String(50), nullable=False)
>
>
> class Schedule(Teacher, Lesson, Aula):
> pass
>
>
> engine = create_engine("sqlite:///sqlalchemy_test.db")
> Base.metadata.create_all(engine)
> Session = sessionmaker(bind=engine)
>
>
> if __name__ == "__main__":
> s = Session()
>
> ## t1 = Teacher(name="gennaro")
> ## t1.lessons = [
> ## Lesson(name="gennaro lesson"),
> ## ]
> ##
> ## t1.aula = [
> ## Aula(nr_aula="B2"),
> ## ]
> ## s.add(t1)
> ##
> ## s.commit()
> ##
> ## t1 = Teacher(name="giulio")
> ## t1.lessons = [
> ## Lesson(name="giulio lesson 1"),
> ## Lesson(name="giulio lesson 2"),
> ## ]
> ##
> ## t1.aula = [
> ## Aula(nr_aula="A3"),
> ## ]
> ## s.add(t1)
> ##
> ## s.commit()
> ##
> ##
> ## t1 = Computer(pc_code="pcn1234")
> ## t1.aula = [
> ## Aula(nr_aula="B2"),
> ## ]
> ## s.add(t1)
> ##
> ## s.commit()
>
> Session = sessionmaker(bind=engine, autoflush=True, autocommit=True)
> session = Session()
> data = session.query(Schedule).filter(Aula.nr_aula=='B2') #
>
> print data
>
> for i in data:
> print i.id, i.name
> for i in i.aula:
> print i.nr_aula
>
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