Python中的单向一对一关系SqlAlchemy

Question

我正在尝试在 SqlAlchemy 中建立 OneToOne 关系，其中孩子的表 ID 已经是外键，但它抛出了错误：

sqlalchemy.orm.exc.DetachedInstanceError: Instance <Vetor at 0x7fcc81307070> is not bound to a Session; attribute refresh operation cannot proceed

下面，两个模型和服务..

class CUBE(types.UserDefinedType):
 def get_col_spec(self, **kw):
   return "CUBE"

class Vetor(db.Model):
   id = db.Column(db.Integer, primary_key=True)
   data = db.Column(db.DateTime(), default=db.func.now())
   vetor = db.Column(CUBE)
   sistema_origem_id = db.Column(db.Integer)
   
   def __init__(self, vetor, sistema_origem):
       self.vetor = vetor
       self.sistema_origem_id = sistema_origem
       
   def __repr__(self):
       return "<Vetor(id='%s', data='%s', vetor='%s', sistema_origem_id='%s')>" % (self.id, self.data, self.vetor, self.sistema_origem_id)

class FBinary(db.Model):
    id = db.Column(db.Integer, db.ForeignKey("vetor.id"), primary_key=True)
    binario = db.Column(db.LargeBinary)
    contenttype = db.Column(db.String())

    def __init__(self, id, binario, contenttype):
        self.id = id
        self.binario = binario
        self.contenttype = contenttype
    
    def __repr__(self):
        return "<FBinary(id='%s', binario='%s', contentype='%s')>" % (self.id, self.binario, self.contenttype)

试图同时提交的类：

    ....code.....

    face = Vetor(vetor, 1 ) 
    db.session.add(face)

    binario = FBinary(id=face, binario=foto_bytes, contenttype='')
    db.session.add(binario)

    db.session.commit()

Answer 1

我无法重现您的错误。话虽如此，一个可能的解决方案应该是：

    face = Vetor(vetor, 1 ) 
    db.session.add(face)
    db.session.comit()  # Now your database has an entry in Table vetor with id 1

    binario = FBinary(id=face.id, binario=foto_bytes, contenttype='')  # reference the id from your face object.
    db.session.add(binario)
    db.session.commit()

我假设 vetor 是某种数据并且不是 Vetor 对象（为什么要尝试将 Vetor 对象保存在 vetor 表中？）。

希望对您有所帮助。请考虑在您的下一个问题中提供minimal reproducible example。