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Re: try pattern for database connection with the close method

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On Sat, Feb 21, 2015 at 5:22 AM, Mark Lawrence <breamoreboy@yahoo.co.uk> wrote:
> On 21/02/2015 02:42, Mario Figueiredo wrote:
>>
>> Hello all,
>>
>> I'm using the following pattern for db access  that requires me to
>> close the connection as soon as it is not needed:
>>
>>          import sqlite3 as lite
>>
>>          try:
>>              db = lite.connect('data.db')
>>          except lite.DatabaseError:
>>              raise OSError('database file corrupt or not found.')
>>          else:
>>              try:
>>                  with db:
>>                      db.execute(sql, parms)
>>              except lite.IntegrityError:
>>                  raise ValueError('invalid data')
>>              finally:
>>                  db.close()
>>
>> Since it's a bit verbose, is there a better way?
>>
>> Note: The user of this API has the whole database functionality
>> abstracted away. Hence the exception channeling in the except clauses.
>>
>
> Use your context manager at the outer level.
>
> import sqlite3 as lite
>
> try:
>     with lite.connect('data.db') as db:
>     try:
>         db.execute(sql, parms)
>     except lite.IntegrityError:
>         raise ValueError('invalid data')
> except lite.DatabaseError:
>     raise OSError('database file corrupt or not found.')

This could result in the OSError being misleadingly raised due to some
DatabaseError raised by the execute rather than the connect.

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try pattern for database connection with the close method Mario Figueiredo <marfig@gmail.com> - 2015-02-21 03:42 +0100
  Re: try pattern for database connection with the close method Chris Kaynor <ckaynor@zindagigames.com> - 2015-02-20 18:59 -0800
  Re: try pattern for database connection with the close method Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-02-21 12:22 +0000
    Re: try pattern for database connection with the close method Mario Figueiredo <marfig@gmail.com> - 2015-02-22 19:41 +0100
      Re: try pattern for database connection with the close method Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-02-22 19:07 +0000
        Re: try pattern for database connection with the close method Mario Figueiredo <marfig@gmail.com> - 2015-02-23 00:25 +0100
      Re: try pattern for database connection with the close method Skip Montanaro <skip.montanaro@gmail.com> - 2015-02-22 13:15 -0600
        Re: try pattern for database connection with the close method Mario Figueiredo <marfig@gmail.com> - 2015-02-23 00:30 +0100
  Re: try pattern for database connection with the close method Ian Kelly <ian.g.kelly@gmail.com> - 2015-02-21 08:16 -0700
  Re: try pattern for database connection with the close method Peter Otten <__peter__@web.de> - 2015-02-21 16:22 +0100
    Re: try pattern for database connection with the close method Mario Figueiredo <marfig@gmail.com> - 2015-02-23 00:35 +0100
  Re: try pattern for database connection with the close method Peter Otten <__peter__@web.de> - 2015-02-21 16:27 +0100
  Re: try pattern for database connection with the close method Ian Kelly <ian.g.kelly@gmail.com> - 2015-02-21 08:50 -0700
  Re: try pattern for database connection with the close method Peter Otten <__peter__@web.de> - 2015-02-21 18:02 +0100

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