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

Elixir是这样做的。这个解决方案的价值在于,它允许递归地包括关系的字典表示。

def to_dict(self, deep={}, exclude=[]):
    """Generate a JSON-style nested dict/list structure from an object."""
    col_prop_names = [p.key for p in self.mapper.iterate_properties \
                                  if isinstance(p, ColumnProperty)]
    data = dict([(name, getattr(self, name))
                 for name in col_prop_names if name not in exclude])
    for rname, rdeep in deep.iteritems():
        dbdata = getattr(self, rname)
        #FIXME: use attribute names (ie coltoprop) instead of column names
        fks = self.mapper.get_property(rname).remote_side
        exclude = [c.name for c in fks]
        if dbdata is None:
            data[rname] = None
        elif isinstance(dbdata, list):
            data[rname] = [o.to_dict(rdeep, exclude) for o in dbdata]
        else:
            data[rname] = dbdata.to_dict(rdeep, exclude)
    return data

其他回答

我不能得到一个好的答案,所以我用这个:

def row2dict(row):
    d = {}
    for column in row.__table__.columns:
        d[column.name] = str(getattr(row, column.name))

    return d

编辑:如果上面的函数太长,不适合某些口味,这里是一个一行(python 2.7+)

row2dict = lambda r: {c.name: str(getattr(r, c.name)) for c in r.__table__.columns}

在@balki回答之后,从SQLAlchemy 0.8开始,您可以使用_asdict(),可用于KeyedTuple对象。这为最初的问题提供了一个非常直接的答案。只是,在你的例子中改变最后两行(for循环):

for u in session.query(User).all():
   print u._asdict()

这是因为在上面的代码中u是类型类KeyedTuple的对象,因为.all()返回KeyedTuple的列表。因此,它有_asdict()方法,该方法很好地将u作为字典返回。

WRT @STB: AFAIK的答案,任何。all()返回的是一个KeypedTuple的列表。因此,无论是否指定列,只要处理的是应用于Query对象的.all()的结果,上述方法都是有效的。

两种方式:

1.

for row in session.execute(session.query(User).statement):
    print(dict(row))

2.

selected_columns = User.__table__.columns
rows = session.query(User).with_entities(*selected_columns).all()
for row in rows :
    print(row._asdict())

Elixir是这样做的。这个解决方案的价值在于,它允许递归地包括关系的字典表示。

def to_dict(self, deep={}, exclude=[]):
    """Generate a JSON-style nested dict/list structure from an object."""
    col_prop_names = [p.key for p in self.mapper.iterate_properties \
                                  if isinstance(p, ColumnProperty)]
    data = dict([(name, getattr(self, name))
                 for name in col_prop_names if name not in exclude])
    for rname, rdeep in deep.iteritems():
        dbdata = getattr(self, rname)
        #FIXME: use attribute names (ie coltoprop) instead of column names
        fks = self.mapper.get_property(rname).remote_side
        exclude = [c.name for c in fks]
        if dbdata is None:
            data[rname] = None
        elif isinstance(dbdata, list):
            data[rname] = [o.to_dict(rdeep, exclude) for o in dbdata]
        else:
            data[rname] = dbdata.to_dict(rdeep, exclude)
    return data

我是一个新晋的Python程序员,遇到了使用join表获取JSON的问题。使用这里的答案中的信息,我构建了一个函数,将合理的结果返回到JSON,其中包括表名,避免使用别名或字段冲突。

简单地传递会话查询的结果:

test = Session()。查询(VMInfo、客户). join(客户).order_by (VMInfo.vm_name) .limit (50) .offset (10)

json = sqlAl2json(test)

def sqlAl2json(self, result):
    arr = []
    for rs in result.all():
        proc = []
        try:
            iterator = iter(rs)
        except TypeError:
            proc.append(rs)
        else:
            for t in rs:
                proc.append(t)

        dict = {}
        for p in proc:
            tname = type(p).__name__
            for d in dir(p):
                if d.startswith('_') | d.startswith('metadata'):
                    pass
                else:
                    key = '%s_%s' %(tname, d)
                    dict[key] = getattr(p, d)
        arr.append(dict)
    return json.dumps(arr)