Delete lines from CSV file using html web page

Question

I am writing a web page that will display the content of a CSV file in a table and I want to add a Delete button at the end of each row that would delete that line in CSV file, but I'm having some problems with the delete button. Here is what i have so far:

<?php
$fileName = "Contacts.csv";

echo "<table> \n\n";
$f = fopen("Contacts.csv", "r");
$i=0;
while (($line = fgetcsv($f)) !== false) {
        echo "<tr>";
        foreach ($line as $cell) {
                echo " <td> " . htmlspecialchars($cell) . " </td> ";
        }
      echo "<td><button type=\"button\" onclick= ?????? >Delete</button></td>";
        echo "</tr>\n";
        $i++;
}
fclose($f);
echo "\n</table>";
$string="Hello";
?>

And then there is a function that I found online for deleting the line in CSV that takes two parameters, the name of CSV file and the nuber of the line to delete.

function delLineFromFile($fileName, $lineNum){
// check the file exists 
  if(!is_writable($fileName))
    {
    // print an error
    print "The file $fileName is not writable";
    // exit the function
    exit;
    }
   else
      {
    // read the file into an array    
    $arr = file($fileName);
    }

  // the line to delete is the line number minus 1, because arrays begin at zero
  $lineToDelete = $lineNum-1;

  // check if the line to delete is greater than the length of the file
  if($lineToDelete > sizeof($arr))
    {
      // print an error
    print "You have chosen a line number, <b>[$lineNum]</b>,  higher than the length of the file.";
    // exit the function
    exit;
    }

   //remove the line
  unset($arr["$lineToDelete"]);

  // open the file for reading
  if (!$fp = fopen($fileName, 'w+'))
    {
    // print an error
    print "Cannot open file ($fileName)";
  // exit the function
    exit;
    }

  // if $fp is valid
  if($fp)
    {
        // write the array to the file
        foreach($arr as $line) { fwrite($fp,$line); }

        // close the file
        fclose($fp);
        }

echo "Contact was deleted successfully!";
}

So actually the problem is that I don't know how to put the appropriate number of line to delete in the function delLineFromFile. Does anyone know how to do that?

Increment a variable `$i` for each line and add that to the `name=` attribute? — Madara's Ghost, Oct 18 '11 at 13:02
I tried doing something in that direction, but then I don't know how to use button names to produce input for the delLineFromFile() function — Jaro, Oct 18 '11 at 13:20
duplicate title http://stackoverflow.com/questions/4072015/remove-line-from-csv-file — ka_lin, Oct 18 '11 at 13:21
Maybe you'd like to use [Python and csv module](http://stackoverflow.com/questions/4521426/delete-blank-rows-from-csv-using-python) instead. Otherwise, you might consider other approach: Instead of deleting the file, break the csv line onto a separate array, implode and then write back without the deleted values. [Try](http://www.codingforums.com/showthread.php?t=59950). — AleksanderKseniya, Oct 24 '11 at 20:41
Hopefully your CSV file isn't too large, as that delete function sucks the entire thing into memory. — Marc B, Oct 27 '11 at 14:24

score 0 · Accepted Answer · answered Oct 27 '11 at 14:21

Here is what worked for me in the end, instead of a button I used http link:

echo "<table> \n\n";
$f = fopen("Contacts.txt", "r");
$i=1;
while (($line = fgetcsv($f)) !== false) {
        echo "<tr>";
        foreach ($line as $cell) {
                echo " <td> " . htmlspecialchars($cell) . " </td> ";
    } 
    echo "<td><a href=\"delete.php?lineNum=$i\">Delete</a></td>";
    echo "<td>$i</td>";

    </td>";
    echo "</tr>\n";
    $i++;
}
fclose($f);
echo "\n</table>";

And then I used $_GET() function to get the variable in the other php script:

$fileName = "Contacts.txt";

// the line to delete
$lineNum = $_GET["lineNum"];

delLineFromFile($fileName, $lineNum);

function delLineFromFile($fileName, $lineNum){
// check the file exists 
  if(!is_writable($fileName))
    {
// print an error
print "The file $fileName is not writable";
// exit the function
exit;
}
  else
  {
// read the file into an array    
$arr = file($fileName);
}

  // the line to delete is the line number minus 1, because arrays begin at zero
  $lineToDelete = $lineNum-1;

  // check if the line to delete is greater than the length of the file
  if($lineToDelete > sizeof($arr))
    {
      // print an error
    print "You have chosen a line number, <b>[$lineNum]</b>,  higher than the length  of the file.";
// exit the function
exit;
}

  //remove the line
  unset($arr["$lineToDelete"]);

  // open the file for reading
  if (!$fp = fopen($fileName, 'w+'))
     {
    // print an error
        print "Cannot open file ($fileName)";
      // exit the function
         exit;
    }

  // if $fp is valid
  if($fp)
    {
    // write the array to the file
    foreach($arr as $line) { fwrite($fp,$line); }

    // close the file
    fclose($fp);
    }

echo "Contact was deleted successfully!";
}

Delete lines from CSV file using html web page

1 Answers1