sqlalchemy:如何通过一个查询联接多个表? [英] sqlalchemy: how to join several tables by one query?

问题描述

我有以下SQLAlchemy映射的类:

I have the following SQLAlchemy mapped classes:

class User(Base):
    __tablename__ = 'users'
    email = Column(String, primary_key=True)
    name = Column(String)

class Document(Base):
    __tablename__ = "documents"
    name = Column(String, primary_key=True)
    author = Column(String, ForeignKey("users.email"))

class DocumentsPermissions(Base):
    __tablename__ = "documents_permissions"
    readAllowed = Column(Boolean)
    writeAllowed = Column(Boolean)

    document = Column(String, ForeignKey("documents.name"))

我需要为user.email = "[e-mail]"获取这样的表:

I need to get a table like this for user.email = "[e-mail]":

email | name | document_name | document_readAllowed | document_writeAllowed

如何使用一个对SQLAlchemy的查询请求来完成?以下代码对我不起作用:

How can it be made using one query request for SQLAlchemy? The code below does not work for me:

result = session.query(User, Document, DocumentPermission).filter_by(email = "[e-mail]").all()

谢谢

推荐答案

尝试一下

q = (Session.query(User,Document,DocumentPermissions)
    .filter(User.email == Document.author)
    .filter(Document.name == DocumentPermissions.document)
    .filter(User.email == 'someemail')
    .all())

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