是否有一种简单的方法来遍历列名和值对?

我的SQLAlchemy版本是0.5.6

下面是我尝试使用dict(row)的示例代码:

import sqlalchemy
from sqlalchemy import *
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

print "sqlalchemy version:",sqlalchemy.__version__ 

engine = create_engine('sqlite:///:memory:', echo=False)
metadata = MetaData()
users_table = Table('users', metadata,
     Column('id', Integer, primary_key=True),
     Column('name', String),
)
metadata.create_all(engine) 

class User(declarative_base()):
    __tablename__ = 'users'
    
    id = Column(Integer, primary_key=True)
    name = Column(String)
    
    def __init__(self, name):
        self.name = name

Session = sessionmaker(bind=engine)
session = Session()

user1 = User("anurag")
session.add(user1)
session.commit()

# uncommenting next line throws exception 'TypeError: 'User' object is not iterable'
#print dict(user1)
# this one also throws 'TypeError: 'User' object is not iterable'
for u in session.query(User).all():
    print dict(u)

在我的系统输出上运行这段代码:

Traceback (most recent call last):
  File "untitled-1.py", line 37, in <module>
    print dict(u)
TypeError: 'User' object is not iterable

当前回答

我找到这篇文章是因为我正在寻找一种将SQLAlchemy行转换为dict的方法。我正在使用SqlSoup…但答案是我自己想出来的,所以,如果它能帮助到别人,我的意见是:

a = db.execute('select * from acquisizioni_motes')
b = a.fetchall()
c = b[0]

# and now, finally...
dict(zip(c.keys(), c.values()))

其他回答

行有一个_asdict()函数,它给出一个字典

In [8]: r1 = db.session.query(Topic.name).first()

In [9]: r1
Out[9]: (u'blah')

In [10]: r1.name
Out[10]: u'blah'

In [11]: r1._asdict()
Out[11]: {'name': u'blah'}

在大多数情况下,列名适合它们。但是你可能会像下面这样写代码:

class UserModel(BaseModel):
    user_id = Column("user_id", INT, primary_key=True)
    email = Column("user_email", STRING)

column.name“user_email”而字段名是“email”,column.name不能像以前那样工作。

sqlalchemy_base_model.py

我把答案写在这里

一个适用于继承类的解决方案:

from itertools import chain
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()


class Mixin(object):
    def as_dict(self):
        tables = [base.__table__ for base in self.__class__.__bases__ if base not in [Base, Mixin]]
        tables.append(self.__table__)
        return {c.name: getattr(self, c.name) for c in chain.from_iterable([x.columns for x in tables])}
class User(object):
    def to_dict(self):
        return dict([(k, getattr(self, k)) for k in self.__dict__.keys() if not k.startswith("_")])

这应该有用。

在python 3.8+中,我们可以使用数据类和它附带的asdict方法来实现这一点:

from dataclasses import dataclass, asdict

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from sqlalchemy import Column, String, Integer, create_engine

Base = declarative_base()
engine = create_engine('sqlite:///:memory:', echo=False)


@dataclass
class User(Base):
    __tablename__ = 'users'

    id: int = Column(Integer, primary_key=True)
    name: str = Column(String)
    email = Column(String)

    def __init__(self, name):
        self.name = name
        self.email = 'hello@example.com'


Base.metadata.create_all(engine)

SessionMaker = sessionmaker(bind=engine)
session = SessionMaker()

user1 = User("anurag")
session.add(user1)
session.commit()

query_result = session.query(User).one()  # type: User
print(f'{query_result.id=:}, {query_result.name=:}, {query_result.email=:}')
# query_result.id=1, query_result.name=anurag, query_result.email=hello@example.com

query_result_dict = asdict(query_result)
print(query_result_dict)
# {'id': 1, 'name': 'anurag'}

关键是使用@dataclass装饰器,并用它的类型(name: str = column (String)行的:str部分)注释每一列。

还要注意,由于电子邮件没有注释,因此它不包括在query_result_dict中。