sqlalchemy öğretici örneği çalışmıyor

Question

sqlalchemy tutorial'da verilen örnek boyunca yoluma çalışıyorum ama hata alıyorum. Mektuba kadar olan örneği takip ettiğimi söyleyebilirim. Şimdiye dek sahip olduğum kod. DB'yi sorguladıktan sonra .first() başarısız olduğunda başarısız olur.

Ben sürümü 0.7.5 ve piton çıkıyorum 2.7

İşte

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

engine = create_engine('sqlite:///:memory:', echo=True) 
engine.execute("select 1").scalar() # works fine 

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

class User(Base): 
    __tablename__ = 'users' 

    id = Column(Integer, primary_key=True) 
    name = Column(String) 
    fullname = Column(String) 
    password = Column(String) 

    def __init__(self, name, fullname, password): 
     self.name = name 
     self.fullname = fullname 
     self.password = password 

    def __repr__(self): 
     return "<User('%s','%s', '%s')>" % (self.name, self.fullname, self.password) 

jeff_user = User("jeff", "Jeff", "foo") 
session.add(jeff_user) 

our_user = session.query(User).filter_by(name='jeff').first() # fails here 

jeff_user.password = "foobar" 

session.add_all([ 
       User('wendy', 'Wendy Williams', 'foobar'), 
       User('mary', 'Mary Contrary', 'xxg527'), 
       User('fred', 'Fred Flinstone', 'blah')]) 

session.dirty # shows nothing as dirty 
session.new # shows nothing as new 

hata mesajı

2012-02-25 17:48:33,879 INFO sqlalchemy.engine.base.Engine BEGIN (implicit) 
2012-02-25 17:48:33,886 INFO sqlalchemy.engine.base.Engine INSERT INTO users (name, fullname, password) VALUES (?, ?, ?) 
2012-02-25 17:48:33,886 INFO sqlalchemy.engine.base.Engine ('jeff', 'Jeff', 'foo') 
2012-02-25 17:48:33,887 INFO sqlalchemy.engine.base.Engine ROLLBACK 
Traceback (most recent call last): 
    File "learning_sql.py", line 35, in <module> 
    our_user = session.query(User).filter_by(name='ed').first() # fails here 
    File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2024, in first 
    ret = list(self[0:1]) 
    File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 1918, in __getitem__ 
    return list(res) 
    File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2092, in __iter__ 
    self.session._autoflush() 
    File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 983, in _autoflush 
    self.flush() 
    File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 1559, in flush 
    self._flush(objects) 
    File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 1630, in _flush 
    flush_context.execute() 
    File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/unitofwork.py", line 331, in execute 
    rec.execute(self) 
    File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/unitofwork.py", line 475, in execute 
    uow 
    File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/mapper.py", line 2291, in _save_obj 
    execute(statement, params) 
    File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1405, in execute 
    params) 
    File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1538, in _execute_clauseelement 
    compiled_sql, distilled_params 
    File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1646, in _execute_context 
    context) 
    File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1639, in _execute_context 
    context) 
    File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/default.py", line 330, in do_execute 
    cursor.execute(statement, parameters) 
sqlalchemy.exc.OperationalError: (OperationalError) no such table: users u'INSERT INTO users (name, fullname, password) VALUES (?, ?, ?)' ('jeff', 'Jeff', 'foo') 

beklenen baskı çıktı Nedense bu

>>> our_user = session.query(User).filter_by(name='ed').first() 
BEGIN (implicit) 
INSERT INTO users (name, fullname, password) VALUES (?, ?, ?) 
('ed', 'Ed Jones', 'edspassword') 
SELECT users.id AS users_id, users.name AS users_name, users.fullname AS users_fullname, users.password AS users_password 
FROM users 
WHERE users.name = ? 
LIMIT 1 OFFSET 0 
('ed',) 
>>> our_user 
<User('ed','Ed Jones', 'edspassword')> 

olduğunu SELECT olması gerektiğinde kodum bir ROLLBACK'e neden oluyor.

Answer 1

Veritabanı, tablo yapısını eksik olduğu için bu hatayı alıyorsunuz (görünüşte bu satırı eğitim dosyasında kaçırdınız, Declare Mapping altyazısında bulunuyor). Sadece masa/model tanımları sonra aşağıdaki ekleyerek şemayı oluşturmak için:

Class User(Base) 
    ... 

# Initialize database schema (create tables) 
Base.metadata.create_all(engine)