Merge two PDF files into single one using MPDF

Question

I am using MPDF library to generate pdf files .I have created two PDF files in my root directory as follows :

$invoice_nos = ['0'=>'ISE-00000014Y18','1'=>'ISE-00000005Y18'];
foreach ($invoice_nos as $key => $invoice_no) {
    $html = 'Invoice No - '.$invoice_no;
    $pdf_file_name = $invoice_no.'.pdf';
    $pdf_file_path = ROOT . '/app/webroot/Service_Invoices/'. DS .$pdf_file_name ;
    ob_start();
    $mpdf = new \mPDF('utf-8', 'A4' ,'','',5,5,36,10,5,4);
    $mpdf->WriteHTML($html,2);
    ob_clean();
    $mpdf->Output($pdf_file_name,'f');
}

Now I want to merge these two files into a single file with different pages. How can I do this? I have searched many examples of it but nothing is working.

Answer 1

mPDF is not the best tool to merge PDF files. You'll be better off with GhostScript:

gs -dBATCH -dSAFER -dNOPAUSE -sDEVICE=pdfwrite -sOutputFile=combined.pdf invoice1.pdf invoice2.pdf

Note: Ghostscript requires a hefty $25,000 annual license for commercial use, or with its AGPL license, you must release your code as open source. Source

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Alternatively, generate both invoices directly to one file:

$invoice_nos = ['0' => 'ISE-00000014Y18', '1' => 'ISE-00000005Y18'];
$mpdf = new \mPDF('utf-8', 'A4', '', '', 5, 5, 36, 10, 5, 4);

foreach ($invoice_nos as $key => $invoice_no) {
    $html = 'Invoice No - ' . $invoice_no;
    $mpdf->WriteHTML($html, 2);
    $mpdf->WriteHTML('<pagebreak>');
}

$pdf_file_name = $invoice_no . 'invoices.pdf';
$mpdf->Output($pdf_file_name, 'f');