PHP update text file

Question

I am creating text file to store my variables from one webpage. When a user clicks an add button(like shopping cart) details are entered into the corresponding text file in the server. My code is given below:

$file = "../file/".$profile.".txt";
$qty=1;
$file_handle = fopen($file, "rb");

$profileID=mysql_query("SELECT * FROM `profile` WHERE `name`='$profile'",$con);
$profileID = mysql_fetch_row($profileID);
$profileID=$profileID[0];
$current = file_get_contents($file);
//$current.=file_put_contents($file, $profile."\n");
$result="SELECT p.*, pk.*,p.id as PID FROM `pricing` p
JOIN (SELECT `distributor`,MAX(`version`) AS ver FROM `pricing` GROUP BY `distributor`) mx ON mx.ver = p.version AND p.distributor = mx.distributor
JOIN `product_picker` pk ON pk.code = p.code AND pk.profile_name=$profileID AND p.id=$productID";
$result=mysql_query($result);
while($row = mysql_fetch_array($result))
{
    $pricingID=$row['PID'];
    $code=$row['code'];
    $buy=$row['buy'];
    $markup=$row['custom markup'];
    $sell=$buy*$markup;
    $buy="$".number_format((float)$sell,2,'.','');
    $stock=explode('.',$row['stock']);
    $stock=$stock[0];
}
if (file_exists($file))
{
    $count=count(file($file));
    while (!feof($file_handle) )
    {
        $line_of_text = fgets($file_handle);
        $parts = explode('|', $line_of_text);
        $pid=trim($parts[0]);
        if($pid==$pricingID)
        {
            $qty=$qty+1;
        }

    }
    fclose($file_handle);
}

    $current.=$pricingID."|".$code.",".$buy.",".$stock."|".$qty."\n";
    file_put_contents($file, $current);

According to the code, the text file format will be:

793|EX-24-AFL,$2425.95,0|1
8078|EX-48-AFL,$3619.35,0|1
866|EX-PWR-320-AC,$303.24,20|1
793|EX-24-AFL,$2425.95,0|2
793|EX-24-AFL,$2425.95,0|3

The first column represents the id(793,8078,866). The above code inserted every time to the text file. But I need to change the last value(qty) if the text file's first column is id already exists.

So the output of text file should be

793|EX-24-AFL,$2425.95,0|3
8078|EX-48-AFL,$3619.35,0|1
866|EX-PWR-320-AC,$303.24,20|1

Anyone please help me?

I want to change the last variable($qty) in each line if there is pricingID(first variable in the line) already occurs. Otherwise insert new line to text file — NewPHP
– NewPHP, Commented Nov 20, 2013 at 2:37
Sorry. Didn't see it. Well main thing that jumps out is you only open the file in write mode. Not gonna update it that way. — ficuscr
– ficuscr, Commented Nov 20, 2013 at 2:55

AlienHoboken · Accepted Answer · 2013-11-20 04:23:12Z

First of all, I'd recommend you not write your own flat file for the shopping cart, but rather create a shopping cart table in your database.

However, if you wish to proceed in this manner, what you want can be accomplished with a small change to your existing code.

if (file_exists($file))
{
    $count=count(file($file));
    $new_file_contents = ""; //contents to overwrite this file with

    while (!feof($file_handle) )
    {
        $line_of_text = fgets($file_handle);
        $parts = explode('|', $line_of_text);
        $pid=trim($parts[0]);
        if($pid==$pricingID)
        {
            $parts[2] = $qty + 1; //store incremented qty in array
            $line_of_text = implode("|", $parts); //use implode to put array back together
        }
        $new_file_contents .= $line_of_text; //store this in new file contents
    }
    fclose($file_handle);
}

file_put_contents($file, $new_file_contents);

However, I'd probably approach this with a regular expression. I feel it's an easier way to tackle this and doesn't deal with iterating over each line of the file.

if (file_exists($file))
{
   $file_contents = file_get_contents($file);

   $pattern = "/(${pid}\|[^\|]*\|)([0-9]+)/"; //establish regex pattern matching lines based on pid
   preg_match($pattern, $file_contents, $matches); //match the line of this pid
   $qty = $matches[2] + 1; //get the quantity currently in cart for this product and increment it
   $replace = '${1}' . $qty; //build our replacement string using a callback and new quantity
   $file_contents = preg_replace($pattern, $replace, $file_contents); //replace it in the file
   file_put_contents($file, $file_contents); //overwrite old file with updated quantity
}

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