如何使这个PHP代码更高效？ （在CSV文件中编辑一行）

Question

This code works, but I just hacked it together with my limited knowledge of PHP and I'm sure there's a more elegant and efficient way to go about it. If you'd be so kind as to point out how I can improve, that would be great!

So I have a CSV file, structured like so:

Code        Class     Value    Status      Date Created    Date Redeemed
========================================================================
a51f3g45    gold      50       valid       2012-08-20      
4f6a2984    silver    200      redeemed    2012-08-23      2012-08-27      
gf3eb54b    gold      150      valid       2012-08-30      

etc...

The user fills out a form to change the Class, Value, and Status fields of a given line. I cobbled together the following code to replace the old values with the new ones:

$file = 'codes.csv';
$old_csv_string = file_get_contents($file);

preg_match('/('.$_POST['code'].',.*,.*,.*,.*,.*)
/',$old_csv_string,$matches);
$old_row = $matches[1];

preg_match('/'.$_POST['code'].',(.*,.*,.*),.*,.*
/',$old_csv_string,$matches_part);
$old_row_part = $matches_part[1];

$new_row_part = $_POST['class'].",".$_POST['value'].",".$_POST['status'];
$new_row = str_replace($old_row_part,$new_row_part,$old_row);
$new_csv_string = str_replace($old_row,$new_row,$old_csv_string);
file_put_contents($file,$new_csv_string);

So can I do better than 10 lines of code? Any advice would be greatly appreciated :)

Note: I tried using fgetcsv, but I couldn't figure out how to find the unique code within a 2D array, then replace its siblings.

Answer 1

Why are you doing this ? I think you should store the data in a SQL table.
Each time user update data, do it in the table.
If you want the CSV to be downloadable at any moment. Use a .htaccess to redirect your.csv to csv_generator.php only if your.csv does not exist.
csv_generator.php will regenerate the whole csv if it does not exist, save it on hard drive for later use, and send it with correct mime/type in header (so it's transparent for user). User don't see he is requesting a php page.
Then you need to delete the csv on hard drive each time someone update the data (so it will be regenerated on next request)

I think this is the way to have an always ready to download csv online.

Do you know google doc does this ? Users can change data in a spreadsheet wich is available to download as a csv from a url (you need to publish this spreadsheet as a csv file).