Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From: Ben Finney <ben+python@benfinney.id.au>
Newsgroups: comp.lang.python
Subject: Re: Best way to inplace alter a list going into postgres
Date: Tue, 31 May 2016 14:54:02 +1000
Lines: 22
Message-ID: <mailman.44.1464670453.1839.python-list@python.org>
References: <705c69aa-f82d-4e03-9d83-bb33ed20ad4d@googlegroups.com> <85r3ci7rpx.fsf@benfinney.id.au>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
X-Trace: news.uni-berlin.de ZM6w3ARq1byf7f9e5BkVhQm8cc8bPBAp3qCaHDaOoNMQ==
Cancel-Lock: sha1:PyM2jIl20Oh4SFP+GnwCbmFZEbk=
Return-Path: <python-python-list@m.gmane.org>
X-Original-To: python-list@python.org
Delivered-To: python-list@mail.python.org
X-Spam-Status: OK 0.002
X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'modify': 0.04; 'correct.': 0.07; 'type,': 0.07; 'alter': 0.09; 'indicates': 0.09; 'postgres': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'subject:into': 0.09; 'question.': 0.13; 'example).': 0.16; 'inability': 0.16; 'received:80.91.229.3': 0.16; 'received:io': 0.16; 'received:plane.gmane.org': 0.16; 'received:psf.io': 0.16; "python's": 0.23; 'split': 0.23; 'header:User-Agent:1': 0.26; 'subject:list': 0.26; 'header:X-Complaints-To:1': 0.26; '(such': 0.27; 'sequence': 0.27; 'record': 0.29; 'convert': 0.29; 'instead,': 0.33; 'list': 0.34; 'mapping': 0.35; 'but': 0.36; 'list,': 0.36; 'should': 0.36; 'to:addr:python-list': 0.36; 'subject:: ': 0.37; 'being': 0.37; 'received:org': 0.37; 'list.': 0.37; 'names': 0.38; 'data': 0.39; 'sure': 0.39; 'to:addr:python.org': 0.40; 'field': 0.60; 'your': 0.60; 'decision': 0.61; '_o__)': 0.84; 'mencken': 0.84; 'received:125': 0.84; '\xe2\x80\x94henry': 0.84; 'subject:Best': 0.93
X-Injected-Via-Gmane: http://gmane.org/
X-Gmane-NNTP-Posting-Host: jigong.madmonks.org
X-Public-Key-ID: 0xAC128405
X-Public-Key-Fingerprint: 517C F14B B2F3 98B0 CB35  4855 B8B2 4C06 AC12 8405
X-Public-Key-URL: http://www.benfinney.id.au/contact/bfinney-pubkey.asc
X-Post-From: Ben Finney <bignose+hates-spam@benfinney.id.au>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.4 (gnu/linux)
X-BeenThere: python-list@python.org
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe: <https://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive: <http://mail.python.org/pipermail/python-list/>
List-Post: <mailto:python-list@python.org>
List-Help: <mailto:python-list-request@python.org?subject=help>
List-Subscribe: <https://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
X-Mailman-Original-Message-ID: <85r3ci7rpx.fsf@benfinney.id.au>
X-Mailman-Original-References: <705c69aa-f82d-4e03-9d83-bb33ed20ad4d@googlegroups.com>
Xref: csiph.com comp.lang.python:109270

Sayth Renshaw <flebber.crue@gmail.com> writes:

> What is the best way to inplace alter a list going into a postgres
> database using split but being sure that the order of items remains
> correct.

That's a trick question. The best way to modify fields of a record is
not with a list.

Instead, you should get the record in the form of a mapping (such as
Python's built-in mapping type, ‘dict’) and alter the fields *by name*.

Ony when it's time to serialise the data should you then convert it to a
list, extracting by the sequence of field names (‘horseattrs’ in your
example).

-- 
 \       “Firmness in decision is often merely a form of stupidity. It |
  `\        indicates an inability to think the same thing out twice.” |
_o__)                                                —Henry L. Mencken |
Ben Finney