sqlachemy中的join如何工作?在
class Enrollments(Base):
__tablename__ = 'Enrollments'
StudentID = Column(INTEGER, ForeignKey('Student.StudentID'))
FinalGrade = Column(VARCHAR(3))
class Student(Base):
__tablename__ = 'Student'
StudentID = Column(INTEGER, primary_key=True)
Name = Column(VARCHAR(100))
EnrolledIn = relationship('Enrollments')
session.query(Student).join(Enrollments).all() #what isn't giving me what I expect
我希望这会给我三列(StudentID,Name,FinalGrade,EnrolledIn),但是它只给了我学生对象,没有应该附加的注册,我做错了什么?在
注册被附加到每个
Student
对象,作为student.EnrolledIn
。在但是连接用于查询,而不是获取;如果您想预先加载它们,则需要
此处记录关系加载:http://docs.sqlalchemy.org/en/rel_0_9/orm/tutorial.html#eager-loading
{{cd3}通常只为cd3}类的名称保留
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