PHP 输出期间的 Mpdf errơr？

Question

我有一个错误，不知道为什么。当我删除带有复选框的部分表单时，它会起作用。当我将其添加回去时出现此错误：

Warning: Cannot modify header information - headers already sent by (output started at /footer.php:22) in mpdf/mpdf.php on line 9420 Fatal error: Uncaught MpdfException: Some data has already been output to browser, can't send PDF file in mpdf/mpdf.php:9422 Stack trace: #0 page-kontakt.php(421): mPDF->Output('Zamowienie2.pdf', 'D')

<?php
get_footer();
require("mpdf/mpdf.php");
require_once __DIR__ . '/mpdf/vendor/autoload.php';

if (isset($_POST['submit'])) {

    $mpdf = new Mpdf('utf-8', 'A4');
    $mpdf->SetDisplayMode('fullwidth');

    $custom_company_data = $_POST['nazwa'];
    $custom_street = $_POST['ulica'];
    $custom_post_code = $_POST['kod'];
    $custom_city = $_POST['miejscowosc'];
    $custom_nip = $_POST['nip'];
    $custom_type = $_POST['typ'];
    $custom_place = $_POST['miejsce'];
    $custom_date = $_POST['data'];
    $custom_time = $_POST['czas'];
    $custom_work_time = $_POST['worktime'];
    $custom_phone = $_POST['phone'];
    $custom_description = $_POST['opis'];
    $custom_work = $_POST['praca'];
    $custom_dojazd = $_POST['dojazd'];
    $custom_ryczalt = $_POST['ryczalt'];
    $custom_cash = $_POST['gotowka'];
    $custom_bank_wire = $_POST['przelew'];
    $custom_ile_dni=$_POST['ile_dni'];
    $custom_vat = $_POST['vat'];
    $custom_odwrotne = $_POST['odwrotne'];
    $custom_by_post = $_POST['poczta'];
    $custom_send_an_email = $_POST['elektroniczne'];
    $custom_address = $_POST['naadres'];
    $custom_pdf_name = date("Y-m-d") . '-' . $custom_company_data;
    $custom_vat = $_POST['vat'];
    $custom_odwrotne = $_POST['odwrotne'];

    if(($_POST['platnosc1'])=='Gotówka'){
        $platnosc='Gotówka';
    }
    elseif(($_POST['platnosc2'])=='Przelew w terminie'){
        $platnosc='Przelewem w terminie: '.$custom_ile_dni;
    }
    else{
        $platnosc='Nie Wybrano opcji';
    }
    echo $custom_company_data . '</br>';

    if(($_POST['vat1']=='VAT23%')){
        $vat='23%';
    }
    elseif(($_POST['vat2']=='Odwrotne obciazenie')){
        $vat='Odwrotne obciążenie';
    }
    else{
        echo'Nie podano formy VATU';
    }
    if(($_POST['wysylka1']=='poczta')){
        $wysylka='Poczta';
    }
    elseif(($_POST['wysylka2']=='elektronicznie')){
        $wysylka='Elektronicznie na e-mail: ' .$custom_address;
    }
    else{
        echo'Nie podano formy wysyłki faktury';
    }

    $mpdf->SetHTMLFooter('some html footer...');

    $html='some html content...';

    $mpdf->WriteHTML($html);
    $mpdf->Output("./wp-content/themes/xxxx/pdf/Zamowienie-$custom_pdf_name.pdf", 'F');
    $mpdf->Output('Zamowienie2.pdf', 'D');
}
?>

Answer 1

footer.php（可能包含在 get_footer(); 中）在第 22 行输出一些内容，这会导致设置（隐式）响应 headers。这导致 $mpdf->Output('Zamowienie2.pdf', 'D'); 无法再设置（相同！）响应的 headers...我猜它试图设置 MIME 类型 application/pdf，而页脚已经设置了 MIME 类型text/html（或类似的）。

尝试评论 get_footer() 看看是否可以解决问题。或者如果它至少改变了错误。

PHP 输出期间的 Mpdf errơr？

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