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
返回this:class:的内容。KeyedTuple作为字典
In [46]: result = aggregate_events[0]
In [47]: type(result)
Out[47]: sqlalchemy.util._collections.result
In [48]: def to_dict(query_result=None):
...: cover_dict = {key: getattr(query_result, key) for key in query_result.keys()}
...: return cover_dict
...:
...:
In [49]: to_dict(result)
Out[49]:
{'calculate_avg': None,
'calculate_max': None,
'calculate_min': None,
'calculate_sum': None,
'dataPointIntID': 6,
'data_avg': 10.0,
'data_max': 10.0,
'data_min': 10.0,
'data_sum': 60.0,
'deviceID': u'asas',
'productID': u'U7qUDa',
'tenantID': u'CvdQcYzUM'}
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。
