Question

我有四个表-用户，加拿大，法国，德国-完全独立。我（我相信）将它们添加到数据库中。但是，除了“用户”之外，所有数据库的列似乎都无法查询，尽管它们在那里。（一个人可以查询它们，但不使用fliter（）或all（）或first（）或对查询结果进行迭代。）我想知道问题是否在于我是否需要使用这个declarative_base东西？

DATABASE_URL = os.environ["DATABASE_URL"]

app = Flask(__name__)      

app.secret_key = "real key will go here"

app.config.update(mail_settings)
app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False
app.config['SQLALCHEMY_DATABASE_URI'] = DATABASE_URL

db = SQLAlchemy(app)

class Users(db.Model):
    __tablename__ = "Users"
    id_ = db.Column(db.Integer, primary_key=True)
    name_ = db.Column(db.String(100))
    email_ = db.Column(db.String(100))
    date_ = db.Column(db.Date())
    count_ = db.Column(db.Integer)
    def __init__(self, email, name, date=datetime.datetime.now().date(), count=0):
        self.name_ = name
        self.email_ = email
        self.date_ = date
        self.count_ = count
    def __repr__(self):
        return '<User %r>' % self.email_

class Canada(db.Model):
    __tablename__ = 'Canada'
    id_ = db.Column(db.Integer, primary_key=True)
    address = db.Column(db.String(100))
    def __init__(self, address):
        self.address = address
    def __repr__(self):
        return "<Canadian address %r>" % self.address

class France(db.Model):
    __tablename__ = "France"
    id_ = db.Column(db.Integer, primary_key=True)
    address = db.Column(db.String(100))
    def __init__(self, address):
        self.address = address
    def __repr__(self):
        return "<French address %r>" % self.address

class Germany(db.Model):
    __tablename__ = "Germany"
    id_ = db.Column(db.Integer, primary_key=True)
    address = db.Column(db.String(100))
    def __init__(self, address):
        self.address = address
    def __repr__(self):
        return "<German address %r>" % self.address

db.create_all()
db.session.commit()

我可以添加用户，然后使用网络表单查询他们，而不会出现任何问题。

但是，当我尝试添加加拿大数据库时（在添加之前我先检查它是否已经存在），我的查询失败：

db.session.query(Canada).filter(Canada.address == address).first()

以下是输出：

2018-09-11T13:49:14.998235+00:00 app[web.1]: Traceback (most recent call last):
2018-09-11T13:49:14.998237+00:00 app[web.1]: File "/app/.heroku/python/lib/python2.7/site-packages/flask/app.py", line 2292, in wsgi_app
2018-09-11T13:49:14.998239+00:00 app[web.1]: response = self.full_dispatch_request()
2018-09-11T13:49:14.998241+00:00 app[web.1]: File "/app/.heroku/python/lib/python2.7/site-packages/flask/app.py", line 1815, in full_dispatch_request
2018-09-11T13:49:14.998242+00:00 app[web.1]: rv = self.handle_user_exception(e)
2018-09-11T13:49:14.998244+00:00 app[web.1]: File "/app/.heroku/python/lib/python2.7/site-packages/flask/app.py", line 1718, in handle_user_exception
2018-09-11T13:49:14.998246+00:00 app[web.1]: reraise(exc_type, exc_value, tb)
2018-09-11T13:49:14.998247+00:00 app[web.1]: File "/app/.heroku/python/lib/python2.7/site-packages/flask/app.py", line 1813, in full_dispatch_request
2018-09-11T13:49:14.998249+00:00 app[web.1]: rv = self.dispatch_request()
2018-09-11T13:49:14.998251+00:00 app[web.1]: File "/app/.heroku/python/lib/python2.7/site-packages/flask/app.py", line 1799, in dispatch_request
2018-09-11T13:49:14.998253+00:00 app[web.1]: return self.view_functions[rule.endpoint](**req.view_args)
2018-09-11T13:49:14.998255+00:00 app[web.1]: File "/app/app.py", line 111, in admin
2018-09-11T13:49:14.998256+00:00 app[web.1]: if db.session.query(Canada).filter(Canada.address == address).first() is None:
2018-09-11T13:49:14.998258+00:00 app[web.1]: File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2888, in first
2018-09-11T13:49:14.998260+00:00 app[web.1]: ret = list(self[0:1])
2018-09-11T13:49:14.998262+00:00 app[web.1]: File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2680, in __getitem__
2018-09-11T13:49:14.998263+00:00 app[web.1]: return list(res)
2018-09-11T13:49:14.998265+00:00 app[web.1]: File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2988, in __iter__
2018-09-11T13:49:14.998267+00:00 app[web.1]: return self._execute_and_instances(context)
2018-09-11T13:49:14.998269+00:00 app[web.1]: File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 3011, in _execute_and_instances
2018-09-11T13:49:14.998270+00:00 app[web.1]: result = conn.execute(querycontext.statement, self._params)
2018-09-11T13:49:14.998272+00:00 app[web.1]: File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 948, in execute
2018-09-11T13:49:14.998274+00:00 app[web.1]: return meth(self, multiparams, params)
2018-09-11T13:49:14.998276+00:00 app[web.1]: File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/sql/elements.py", line 269, in _execute_on_connection
2018-09-11T13:49:14.998278+00:00 app[web.1]: return connection._execute_clauseelement(self, multiparams, params)
2018-09-11T13:49:14.998279+00:00 app[web.1]: File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1060, in _execute_clauseelement
2018-09-11T13:49:14.998281+00:00 app[web.1]: compiled_sql, distilled_params
2018-09-11T13:49:14.998282+00:00 app[web.1]: File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1200, in _execute_context
2018-09-11T13:49:14.998284+00:00 app[web.1]: context)
2018-09-11T13:49:14.998297+00:00 app[web.1]: File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1413, in _handle_dbapi_exception
2018-09-11T13:49:14.998299+00:00 app[web.1]: exc_info
2018-09-11T13:49:14.998300+00:00 app[web.1]: File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/util/compat.py", line 265, in raise_from_cause
2018-09-11T13:49:14.998302+00:00 app[web.1]: reraise(type(exception), exception, tb=exc_tb, cause=cause)
2018-09-11T13:49:14.998304+00:00 app[web.1]: File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1193, in _execute_context
2018-09-11T13:49:14.998305+00:00 app[web.1]: context)
2018-09-11T13:49:14.998308+00:00 app[web.1]: File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/engine/default.py", line 509, in do_execute
2018-09-11T13:49:14.998310+00:00 app[web.1]: cursor.execute(statement, parameters)
2018-09-11T13:49:14.998311+00:00 app[web.1]: ProgrammingError: (psycopg2.ProgrammingError) column Canada.address does not exist
2018-09-11T13:49:14.998313+00:00 app[web.1]: LINE 1: SELECT "Canada".id_ AS "Canada_id_", "Canada".address AS "Ca...
2018-09-11T13:49:14.998315+00:00 app[web.1]: ^
2018-09-11T13:49:14.998318+00:00 app[web.1]: [SQL: 'SELECT "Canada".id_ AS "Canada_id_", "Canada".address AS "Canada_address" \nFROM "Canada" \nWHERE "Canada".address = %(address_1)s \n LIMIT %(param_1)s'] [parameters: {'address_1': u'123 fake st. canada\r', 'param_1': 1}] (Background on this error at: http://sqlalche.me/e/f405)

我尝试了很多事情-将代码移到不同的文件中，添加一些涉及“引擎”的代码，更改加拿大列的名称，更改加拿大的名称-但似乎没有任何问题。我注意到的一件事是，我遵循的所有教程在其数据库中仅使用一个表。我想知道这是否是问题的核心。我一直找不到使用多个独立表的指南。

似乎这些列在那里。

>>> for column in Users.__table__.columns:
...     print column
... 
Users.id_
Users.name_
Users.email_
Users.date_
Users.count_
>>> mapper = inspect(Users)
>>> for column in mapper.attrs:
...     print column
... 
Users.id_
Users.name_
Users.email_
Users.date_
Users.count_
>>> 

>>> from sqlalchemy import inspect
>>> mapper = inspect(Canada)
>>> for column in mapper.attrs:
...     print column
... 
Canada.id_
Canada.address
>>> for column in Canada.__table__.columns:
...     print column
... 
Canada.id_
Canada.address

我不知道为什么我的脚本可以查询“用户”列而不是加拿大的列。

那么SQLAlchemy为什么在其中找不到该列的地方生成查询呢？

2018-09-11T13:49:14.998311+00:00 app[web.1]: ProgrammingError: (psycopg2.ProgrammingError) column Canada.address does not exist
2018-09-11T13:49:14.998313+00:00 app[web.1]: LINE 1: SELECT "Canada".id_ AS "Canada_id_", "Canada".address AS "Ca...
2018-09-11T13:49:14.998315+00:00 app[web.1]: ^
2018-09-11T13:49:14.998318+00:00 app[web.1]: [SQL: 'SELECT "Canada".id_ AS "Canada_id_", "Canada".address AS "Canada_address" \nFROM "Canada" \nWHERE "Canada".address = %(address_1)s \n LIMIT %(param_1)s'] [parameters: {'address_1': u'123 fake st. canada\r', 'param_1': 1}] (Background on this error at: http://sqlalche.me/e/f405)

当我做heroku run python时，会看到以下内容：

`>>> from app import db, Users, Canada
>>> db.session.query(Users).all()
[<User u'mhd@example.com'>, <User u'md@example.edu'>]
>>> db.session.query(Canada).all()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2836, in all
    return list(self)
  File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2988, in __iter__
    return self._execute_and_instances(context)
  File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 3011, in _execute_and_instances
    result = conn.execute(querycontext.statement, self._params)
  File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 948, in execute
    return meth(self, multiparams, params)
  File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/sql/elements.py", line 269, in _execute_on_connection
    return connection._execute_clauseelement(self, multiparams, params)
  File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1060, in _execute_clauseelement
    compiled_sql, distilled_params
  File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1200, in _execute_context
    context)
  File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1413, in _handle_dbapi_exception
    exc_info
  File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/util/compat.py", line 265, in raise_from_cause
    reraise(type(exception), exception, tb=exc_tb, cause=cause)
  File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1193, in _execute_context
    context)
  File "/app/.heroku/python/lib/python2.7/site-packages/sqlalchemy/engine/default.py", line 509, in do_execute
    cursor.execute(statement, parameters)
sqlalchemy.exc.ProgrammingError: (psycopg2.ProgrammingError) column Canada.address does not exist
LINE 1: SELECT "Canada".id_ AS "Canada_id_", "Canada".address AS "Ca...
                                             ^
 [SQL: 'SELECT "Canada".id_ AS "Canada_id_", "Canada".address AS "Canada_address" \nFROM "Canada"'] (Background on this error at: http://sqlalche.me/e/f405)

Users和Canada之间有一些绝对不同。

Answer 1

也许您需要检查“加拿大”表中是否存在“地址”字段，因为该日志向您显示了postgres数据库错误：

(psycopg2.ProgrammingError) column Canada.address does not exist

如果表中不存在该字段，则需要运行迁移或使用postgres命令“添加列”（alter table documentantion）手动将其添加到数据库中

我希望这能奏效：）

SQLAlchemy建议表缺少其具有的列：ProgrammingError：（psycopg2.ProgrammingError）列Canada.address不存在

1 个答案: