SqlAlchemy - 按关系属性过滤 [英] SqlAlchemy - Filtering by Relationship Attribute

问题描述

我对 SQLAlchemy 没有太多经验，我遇到了无法解决的问题.我尝试搜索并尝试了很多代码.这是我的类(简化为最重要的代码):

I don't have much experience with SQLAlchemy and I have a problem, which I can't solve. I tried searching and I tried a lot of code. This is my Class (reduced to the most significant code):

class Patient(Base):
    __tablename__ = 'patients'
    id = Column(Integer, primary_key=True, nullable=False)
    mother_id = Column(Integer, ForeignKey('patients.id'), index=True)
    mother = relationship('Patient', primaryjoin='Patient.id==Patient.mother_id', remote_side='Patient.id', uselist=False)
    phenoscore = Column(Float)

我想查询所有患者，其母亲的phenoscore是(例如)== 10

and I would like to query all patients, whose mother's phenoscore is (for example) == 10

如上所述，我尝试了很多代码，但我不明白.在我看来，逻辑上的解决方案是

As told, I tried a lot of code, but I don't get it. The logically solution, in my eyes, would be

patients = Patient.query.filter(Patient.mother.phenoscore == 10)

因为，您可以在输出时为每个元素访问 .mother.phenoscore 但是，此代码不这样做.

because, you can access .mother.phenoscore for each element when outputting but, this code doesn't do it.

是否有(直接)可能通过关系的属性进行过滤(无需编写 SQL 语句或额外的连接语句)，我不止一次需要这种过滤器.

Is there a (direct) possibility to filter by an attribute of a relationship (without writing the SQL Statement, or an extra join-statement), I need this kind of filter more than one time.

即使没有简单的解决方案，我也很高兴得到所有答案.

Even if there is no easy solution, I am happy to get all answers.

推荐答案

使用方法 has() 关系(更易读):

Use method has() of relationship (more readable):

patients = Patient.query.filter(Patient.mother.has(phenoscore=10))

或加入(通常更快):

patients = Patient.query.join(Patient.mother, aliased=True)
                    .filter_by(phenoscore=10)

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