la gestion des erreurs Flask

Question

Je suis en train de rattraper une erreur générée par flacon-sqlalchemy. malheureusement mon code ne peut pas gérer l'erreur car le débogueur attrape d'abord. Il arrive lorsque je tente d'insérer un enregistrement dans une base de données avec un champ qui est censé être unique, mais est duplicated.Is-il un moyen de contourner cela? C'est le retraçage.

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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J'ai oublié de mentionner comment réagit de ballon lorsque je tente de gérer l'erreur. Je reçois quelque chose lié à un monde non défini. Voici le retraçage pour cela.

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

Vous devez mettre un try / catch dans votre fonction create_user (masterpieces_of_code / app.py) dans le bloc de code qui fait la db.session.commit(), et gérer l'exception là.

Mise à jour: Si vous obtenez un NameError pour IntegrityError alors cela signifie que vous êtes susceptible de manquer un

from sqlalchemy.exc import IntegrityError

dans votre app.py. Ce n'est pas un message de Flask, qui est Python vous parler un nom inconnu (à cause de l'importation manquante) car il interprète le code app.py.