How Merging multiple CSV files without headers being repeated (using PHP)? - php

Question

I'm very rookie in PHP and when I combine several csv files with this code, several headers are shown. How could I leave a single header?
I am using a ubuntu 18.04 server with PHP 7.1
<?php
$csvdir = "./csv";
$csvcontent = '';
if (is_dir($csvdir)) {
if ($handle = opendir($csvdir)) {
while (($file = readdir($handle)) !== false) {
if (substr($file, -4) === ".csv") {
$csvcontent .= file_get_contents($csvdir . $file);
}
}
closedir($handle);
}
}
$result = fopen('./todos.csv', 'w');
fwrite($result, $csvcontent);
fclose($result);
?>

Answer 1

According to this answer with example code to skip first lines after getting file contents:
$content = file_get_contents($filename);
$lines = explode("\n", $content);
$skipped_content = implode("\n", array_slice($lines, 2));
You might alter your code like this (although, personally, i might simply alter the production of the csv files to stop producing headers...as exploding the content could slow down your processes).
<?php
$got_headers = 0;
$csvdir = "./csv";
$csvcontent = '';
if (is_dir($csvdir)) {
if ($handle = opendir($csvdir)) {
while (($file = readdir($handle)) !== false) {
if (substr($file, -4) === ".csv") {
if (empty($got_headers)) {
// get the headers the first time only
$csvcontent .= file_get_contents($csvdir . $file);
$got_headers = 1;
} else {
// now, pull the lines after the first
$content = file_get_contents($csvdir . $file);
$lines = explode("\n", $content);
$csvcontent .= implode("\n", array_slice($lines, 1));
}
}
}
closedir($handle);
}
}
$result = fopen('./todos.csv', 'w');
fwrite($result, $csvcontent);
fclose($result);

Answer 2

This has the added benefit of not requiring you to hold the entirety of the resulting file in memory:
$files = []; // use your existing code to build a list of files
$first = true;
$out = fopen('todos.csv', 'wb');
foreach( $files as $file ) {
$in = fopen($file, 'rb');
$line = fread($in); // get the header line
// write only the first file's header
if( $first ) {
fwrite($out, $line);
$first = false;
}
// transcribe the rest of the file.
while( $line = fread($in) ) {
fwrite($out, $line);
}
fclose($in);
}
fclose($out);