From: Charles Calvert <cbciv@...>
Date: 2010-10-27T04:33:06+09:00
Subject: Re: Update a particular Field in a csv file

Probably too late to help the OP, but in case anyone finds this in an
archive ...

On Thu, 15 Apr 2010 08:35:40 -0500, Antony Nambikkai
<nas@srasys.co.in> wrote in
<9194cbbbcba0148e8db87e3a509aee6b@ruby-forum.com>:

>Hi Friends,
>
>I am having a role.csv file as like
>
>emp_id,dep_id,role,salary,accepted
>1,1,SSE,10000,YES
>2,2,SSE,11000,NO
>3,1,SSE,9000,YES
>4,2,SSE,12000,YES
>5,1,SSE,8000,NO
>
>Now, I need to update this role.csv file as like below
>
>emp_id,dep_id,role,salary,accepted
>1,1,SSE,10000,NO
>2,2,SSE,11000,YES
>3,1,SSE,9000,NO
>4,2,SSE,12000,YES
>5,1,SSE,8000,NO

[snip code]

>I am facing 2 issues in this
>
>1. For every updating the CSV file, I am rewriting the whole CSV file.
>That not a teddy way to do it.
>2. I am opening the file first time for reading and 2nd time for
>writing. That is also not convincing me.

The problem is that you're dealing with a single file, not a database.
In order to alter the contents of that file, you're going to have to
read the entire thing into memory, alter it, and then write it back
out to disk.  That's just the way it works.

You could always move the data into a database, which would allow you
to update only an individual record.
-- 
Charles Calvert
Moderator - alt.computer.consultants.moderated
Submission Address: accm@celticwolf.net
Contact Address: accm_mod@celticwolf.net