烧瓶错误处理

Question

我想抓住flask-sqlalchemy产生的错误。不幸的是，我的代码无法处理错误，因为调试器首先捕获它。它发生在我试图插入一个记录到一个应该是唯一但重复的字段的数据库中。有没有办法解决这个问题？这是追溯。

sqlalchemy.exc.IntegrityError 

IntegrityError: (IntegrityError) column username is not unique u'INSERT INTO user (username, password, karma) VALUES (?, ?, ?)' (u'Test', u'test', 0) 
Traceback (most recent call last) 

    * 
     File "/home/josh/Projects/masterpieces_of_code/env/lib/python2.6/site-packages/flask/app.py", line 889, in __call__ 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] return self.wsgi_app(environ, start_response) 

    * 
     File "/home/josh/Projects/masterpieces_of_code/env/lib/python2.6/site-packages/flask/app.py", line 879, in wsgi_app 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] response = self.make_response(self.handle_exception(e)) 

    * 
     File "/home/josh/Projects/masterpieces_of_code/env/lib/python2.6/site-packages/flask/app.py", line 876, in wsgi_app 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] rv = self.dispatch_request() 

    * 
     File "/home/josh/Projects/masterpieces_of_code/env/lib/python2.6/site-packages/flask/app.py", line 695, in dispatch_request 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] return self.view_functions[rule.endpoint](**req.view_args) 

    * 
     File "/home/josh/Projects/masterpieces_of_code/app.py", line 70, in create_user 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] db.session.commit() 

    * 
     File "/usr/share/pyshared/sqlalchemy/orm/scoping.py", line 129, in do 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] return getattr(self.registry(), name)(*args, **kwargs) 

    * 
     File "/usr/share/pyshared/sqlalchemy/orm/session.py", line 653, in commit 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] self.transaction.commit() 

    * 
     File "/usr/share/pyshared/sqlalchemy/orm/session.py", line 364, in commit 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] self._prepare_impl() 

    * 
     File "/usr/share/pyshared/sqlalchemy/orm/session.py", line 348, in _prepare_impl 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] self.session.flush() 

    * 
     File "/usr/share/pyshared/sqlalchemy/orm/session.py", line 1346, in flush 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] self._flush(objects) 

    * 
     File "/usr/share/pyshared/sqlalchemy/orm/session.py", line 1427, in _flush 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] flush_context.execute() 

    * 
     File "/usr/share/pyshared/sqlalchemy/orm/unitofwork.py", line 299, in execute 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] rec.execute(self) 

    * 
     File "/usr/share/pyshared/sqlalchemy/orm/unitofwork.py", line 443, in execute 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] uow 

    * 
     File "/usr/share/pyshared/sqlalchemy/orm/mapper.py", line 1833, in _save_obj 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] execute(statement, params) 

    * 
     File "/usr/share/pyshared/sqlalchemy/engine/base.py", line 1794, in execute 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] object, *multiparams, **params) 

    * 
     File "/usr/share/pyshared/sqlalchemy/interfaces.py", line 149, in execute 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] return execute(clauseelement, *multiparams, **params) 

    * 
     File "/usr/share/pyshared/sqlalchemy/engine/base.py", line 1157, in execute 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] params) 

    * 
     File "/usr/share/pyshared/sqlalchemy/engine/base.py", line 1237, in _execute_clauseelement 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] return self.__execute_context(context) 

    * 
     File "/usr/share/pyshared/sqlalchemy/engine/base.py", line 1268, in __execute_context 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] context.parameters[0], context=context) 

    * 
     File "/usr/share/pyshared/sqlalchemy/engine/base.py", line 1806, in _cursor_execute 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] cursor, statement, parameters, context, False) 

    * 
     File "/home/josh/Projects/masterpieces_of_code/env/lib/python2.6/site-packages/flaskext/sqlalchemy.py", line 115, in cursor_execute 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] return execute(cursor, statement, parameters, context) 

    * 
     File "/usr/share/pyshared/sqlalchemy/engine/base.py", line 1367, in _cursor_execute 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] context) 

    * 
     File "/usr/share/pyshared/sqlalchemy/engine/base.py", line 1360, in _cursor_execute 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] context) 

    * 
     File "/usr/share/pyshared/sqlalchemy/engine/default.py", line 288, in do_execute 

     [Display the sourcecode for this frame] [Open an interactive python shell in this frame] cursor.execute(statement, parameters) 

    IntegrityError: (IntegrityError) column username is not unique u'INSERT INTO user (username, password, karma) VALUES (?, ?, ?)' (u'Test', u'test', 0) 

This is the Copy/Paste friendly version of the traceback. You can also paste this traceback into the public lodgeit pastebin: 

Traceback (most recent call last): 
    File "/home/josh/Projects/masterpieces_of_code/env/lib/python2.6/site-packages/flask/app.py", line 889, in __call__ 
    return self.wsgi_app(environ, start_response) 
    File "/home/josh/Projects/masterpieces_of_code/env/lib/python2.6/site-packages/flask/app.py", line 879, in wsgi_app 
    response = self.make_response(self.handle_exception(e)) 
    File "/home/josh/Projects/masterpieces_of_code/env/lib/python2.6/site-packages/flask/app.py", line 876, in wsgi_app 
    rv = self.dispatch_request() 
    File "/home/josh/Projects/masterpieces_of_code/env/lib/python2.6/site-packages/flask/app.py", line 695, in dispatch_request 
    return self.view_functions[rule.endpoint](**req.view_args) 
    File "/home/josh/Projects/masterpieces_of_code/app.py", line 70, in create_user 
    db.session.commit() 
    File "/usr/share/pyshared/sqlalchemy/orm/scoping.py", line 129, in do 
    return getattr(self.registry(), name)(*args, **kwargs) 
    File "/usr/share/pyshared/sqlalchemy/orm/session.py", line 653, in commit 
    self.transaction.commit() 
    File "/usr/share/pyshared/sqlalchemy/orm/session.py", line 364, in commit 
    self._prepare_impl() 
    File "/usr/share/pyshared/sqlalchemy/orm/session.py", line 348, in _prepare_impl 
    self.session.flush() 
    File "/usr/share/pyshared/sqlalchemy/orm/session.py", line 1346, in flush 
    self._flush(objects) 
    File "/usr/share/pyshared/sqlalchemy/orm/session.py", line 1427, in _flush 
    flush_context.execute() 
    File "/usr/share/pyshared/sqlalchemy/orm/unitofwork.py", line 299, in execute 
    rec.execute(self) 
    File "/usr/share/pyshared/sqlalchemy/orm/unitofwork.py", line 443, in execute 
    uow 
    File "/usr/share/pyshared/sqlalchemy/orm/mapper.py", line 1833, in _save_obj 
    execute(statement, params) 
    File "/usr/share/pyshared/sqlalchemy/engine/base.py", line 1794, in execute 
    object, *multiparams, **params) 
    File "/usr/share/pyshared/sqlalchemy/interfaces.py", line 149, in execute 
    return execute(clauseelement, *multiparams, **params) 
    File "/usr/share/pyshared/sqlalchemy/engine/base.py", line 1157, in execute 
    params) 
    File "/usr/share/pyshared/sqlalchemy/engine/base.py", line 1237, in _execute_clauseelement 
    return self.__execute_context(context) 
    File "/usr/share/pyshared/sqlalchemy/engine/base.py", line 1268, in __execute_context 
    context.parameters[0], context=context) 
    File "/usr/share/pyshared/sqlalchemy/engine/base.py", line 1806, in _cursor_execute 
    cursor, statement, parameters, context, False) 
    File "/home/josh/Projects/masterpieces_of_code/env/lib/python2.6/site-packages/flaskext/sqlalchemy.py", line 115, in cursor_execute 
    return execute(cursor, statement, parameters, context) 
    File "/usr/share/pyshared/sqlalchemy/engine/base.py", line 1367, in _cursor_execute 
    context) 
    File "/usr/share/pyshared/sqlalchemy/engine/base.py", line 1360, in _cursor_execute 
    context) 
    File "/usr/share/pyshared/sqlalchemy/engine/default.py", line 288, in do_execute 
    cursor.execute(statement, parameters) 
IntegrityError: (IntegrityError) column username is not unique u'INSERT INTO user (username, password, karma) VALUES (?, ?, ?)' (u'Test', u'test', 0) 

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我忘记提及烧瓶如何反应，当我尝试处理错误。我得到一些与未定义的全球相关的东西。这就是追溯。

Traceback (most recent call last): 
    File "/home/josh/Projects/masterpieces_of_code/env/lib/python2.6/site-packages/flask/app.py", line 889, in __call__ 
    return self.wsgi_app(environ, start_response) 
    File "/home/josh/Projects/masterpieces_of_code/env/lib/python2.6/site-packages/flask/app.py", line 879, in wsgi_app 
    response = self.make_response(self.handle_exception(e)) 
    File "/home/josh/Projects/masterpieces_of_code/env/lib/python2.6/site-packages/flask/app.py", line 876, in wsgi_app 
    rv = self.dispatch_request() 
    File "/home/josh/Projects/masterpieces_of_code/env/lib/python2.6/site-packages/flask/app.py", line 695, in dispatch_request 
    return self.view_functions[rule.endpoint](**req.view_args) 
    File "/home/josh/Projects/masterpieces_of_code/app.py", line 72, in create_user 
    except(IntegrityError): 
NameError: global name 'IntegrityError' is not defined 

Answer 1

你需要把一个try/catch在你create_user功能（masterpieces_of_code/app.py）中的代码做了db.session.commit()块，并处理异常那里。

更新：如果你正在为IntegrityError一个NameError那么就意味着你很可能在你的app.py缺少

from sqlalchemy.exc import IntegrityError 

。这不是Flask的消息，那是Python告诉你一个未知名称（因为缺少导入），因为它解释app.py中的代码。