OperationalError：（OperationalError）no such column

Question

我遇到问题。我不得不这样做查询：

@app.route('/api/subscriptions/<string:id>', methods=('DELETE',)) 
@decorators.login_required 
def delete_subscription(id): 
    dbsession = DBSession() 
    session = Session() 
    favorit = (dbsession.query(StudentsFavorites) 
     .filter(Exams.number == str(id)) 
     .filter(StudentsFavorites.exam_id) 
     .filter(Students.id == StudentsFavorites.student_id) 
     .filter(Students.id == str(session.get_user_id())) 
     .delete()  ) 
    dbsession.flush() 
    return jsonify(error=False) 

但是，当我做到这一点查询，我得到这个异常：

OperationalError: (OperationalError) no such column: exams.number u'DELETE FROM students_favorites WHERE exams.number = ? AND students_favorites.exam_id AND students.id = students_favorites.student_id AND students.id = ?' ('123123123', 'a24213') 

的表非常大，有很多的信息，所以我不能发布所有的。但这个查询工作：

@app.route('/api/subscriptions/<string:id>', methods=('PUT',)) 
@decorators.login_required 
def add_subscription(id): 
    dbsession = DBSession() 
    session = Session() 
    examID = (dbsession.query(Exams.id) 
    .filter(Exams.number == id).first() 
    ) 
    favorit=StudentsFavorites(student_id=session.get_user_id(), exam_id=examID.id) 
    dbsession.add(favorit) 
    dbsession.flush() 
    return jsonify(error=False) 

短视图表：

table: Exams 
rows: id, number (number is the id i put into the function) 

table: StudentsFavorites 
rows: student_id, exams_id 

table: Students 
rows: id 

我真的不明白，他为什么不找数行中的例外。

编辑：

数据库StudentsFavorites：

class StudentsFavorites(Base): 
    """N:M resolve model for the exams to the semester. 
    """ 

    __tablename__ = "students_favorites" 

    student_id = Column(Unicode(255), ForeignKey("students.id"), primary_key=True, autoincrement=False) 

    exam_id = Column(Integer, ForeignKey("exams.id"),   primary_key=True, autoincrement=False) 

    created_at = Column(DateTime, nullable = False, default = datetime.now) 

    student = relationship("Students", uselist = False, lazy="joined") 

    exam = relationship("Exams", uselist=False, lazy="joined") 

像这样的事情？我尝试这样做：

(dbsession.query(StudentsFavorites) 
      .filter(StudentsFavorites.exam.id == str(id)) 
      .filter(StudentsFavorites.student.id == str(session.get_user_id())) 
      .delete() 
) 

但得到的错误，该ID没有在考试中存在/学生

Answer 1

你有同样的问题的两种情况。您的查询有关于StudentFavorites的信息，这意味着它了解StudentFavorites.student_id和StudentFaovrites.exams_id。它不知道任何关于Students.id，Exames.id和Exames.number。 In order for you to query a StudentFavorites object and have it know about those other values you're going to have to perform a sql join。

Join's可能会在sqlalchemy（以及...在常规sql中）中工作时感到有点痛苦。由于我不知道你的表格模式是什么，所以我不能谈论它，但是视图应该看起来像这样。

@app.route('/api/subscriptions/<string:id>', methods=('DELETE',)) 
@decorators.login_required 
def delete_subscription(id): 
    dbsession = DBSession() 
    session = Session() 
    favorit = (dbsession.query(StudentsFavorites) 
     .join(Exames) 
     .join(students) 
     .filter(Exams.number == str(id)) 
     .filter(StudentsFavorites.exam_id) 
     .filter(Students.id == StudentsFavorites.student_id) 
     .filter(Students.id == str(session.get_user_id())) 
     .delete()  ) 
    dbsession.flush() 
    return jsonify(error=False) 

Alternatively, you can look into setting up Foreign key relationships in your table statements if you use the ORM to create your tables

你的第二个例子作品的原因是因为你指定了考试表的查询和使用只在该表中找到的值。

响应编辑： Right now your table relationships aren't set up correctly.具体的章节：许多要从许多许多和删除行到许多表

此示例代码在得多（更好）详细地解释发布的链接，但基本的想法是，你有一个associate_table（在你的情况StudentFavorites）包含的外键有一个或多个其他表中指定的关系。我个人建议你使用表格示例而不是对象示例。

association_table = Table('association', Base.metadata, 
    Column('left_id', Integer, ForeignKey('left.id')), 
    Column('right_id', Integer, ForeignKey('right.id')) 
) 

class Parent(Base): 
    __tablename__ = 'left' 
    id = Column(Integer, primary_key=True) 
    children = relationship("Child", 
        secondary=association_table, 
        backref="parents") 

class Child(Base): 
    __tablename__ = 'right' 
    id = Column(Integer, primary_key=True)