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求助：TCPDF多语言PDF页眉页脚图片切换遇致命错误

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安全阿岳
2026-7-25
问题：根据网站选中语言切换TCPDF页眉页脚图片

我使用TCPDF开发产品数据单PDF生成器，可生成包含产品描述、特性、标准、技术参数的PDF文档。目前已实现PDF中文本内容的多语言切换，但在尝试根据网站选中的语言切换PDF页眉页脚图片时遇到问题。

相关OCPDF类代码 

<?php
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

require_once DIR_SYSTEM . 'config/si/tcpdf/tcpdf.php';
class OCPDF extends TCPDF {
    public function Header() {
        
                if ($this->request->server['HTTPS']) {
                    $server = HTTP_SERVER;
                } else {
                    $server = HTTPS_SERVER;
                }  
              
                //$language = $this->config->get('config_language'); ERROR IT WAS A TEST BUT DOEST WORK
                $language = 'pt-pt'; // Replace with the actual language code
                if (isset($this->session->data['language'])) {
                    $language = $this->session->data['language'];
                }

                // Set the image file based on the language
                $logo_file = 'image/catalog/pdftemplate/header.png';
                if ($language == 'en-gb') {
                    $logo_file = $server . 'image/catalog/pdftemplate/header-en.png';
                } elseif ($language == 'es') {
                    $logo_file = $server . 'image/catalog/pdftemplate/header-es.png';
                } elseif ($language == 'pt-pt') {
                    $logo_file = $server . 'image/catalog/pdftemplate/header-pt.png';
                }

                $header_details_address = $this->header_details_address;
                 $header_details_email = $this->header_details_email;
             echo $language;  
$header_html = <<<EOD

<img src ="$logo_file" height="190px">
<br/><br/><br/><br/>

EOD;

                    // Print text using writeHTMLCell()
                    $this->writeHTMLCell(0, 0, '', '', $header_html, 0, 1, 0, true, '', true);
                }

                // Page footer
                public function Footer() {
                    // Position at 15 mm from bottom
                    $this->SetY(-25);
                    // Set font
                    $this->SetFont('helvetica', 'I', 8);
                    // Page number
                    
                    if ($this->request->server['HTTPS']) {
                        $server = HTTP_SERVER;
                    } else {
                        $server = HTTPS_SERVER;
                    }  
                    
                    $mlogo_file =  $server.'image/catalog/pdftemplate/footer.png' ;
                    
                    $footer_logo_html = '<div style="width:100% !important;height:190px;"><img width:"100%;" src="' . $footer_image_file . '" /></div>';
                    $this->writeHTMLCell(0, 0, $this->Image($mlogo_file, '0', $this->GetY()+2, '210', 24, '', '', 'T', false, 300, '', false, false, 1, false, false, false), 0, false, 'C', 0, '', 0, false, 'T', 'M');
                }
                
                public function setImageFile($logo_file)
                {
                    $this->logo_file = $logo_file ;
                }
                
                public function setStoreheader_details($header_details_address ,$header_details_email)
                {
                    $this->header_details_address=$header_details_address;
                    $this->header_details_email = $header_details_email;
                }
            }

尝试获取语言的代码片段 

//$language = $this->config->get('config_language'); ERROR IT WAS A TEST BUT DOEST WORK
$language = 'pt-pt'; // Replace with the actual language code
if (isset($this->session->data['language'])) {
$language = $this->session->data['language'];
}

// Set the image file based on the language
$logo_file = 'image/catalog/pdftemplate/header.png';
if ($language == 'en-gb') {
    $logo_file = $server . 'image/catalog/pdftemplate/header-en.png';
} elseif ($language == 'es') {
    $logo_file = $server . 'image/catalog/pdftemplate/header-es.png';
} elseif ($language == 'pt-pt') {
    $logo_file = $server . 'image/catalog/pdftemplate/header-pt.png';
}

文本多语言切换的控制器代码 

class ControllerExtensionModulesiproductpdf extends Controller {
private $modulePath;
public function __construct($registry) {

            parent::__construct($registry);
            $this->config->load('si/siproductpdf');
            $this->modulePath = $this->config->get('siproductpdf_path');

        }

        public function index($settings){
            
            ///
            if (isset($this->request->get['product_id'])) {
                $product_id = (int)$this->request->get['product_id'];
            } else {
                $product_id = 0;
            }
            
            $this->document->addStyle('catalog/view/theme/default/stylesheet/siproductpdf.css');
            //$data['moduleData'] = $settings['siproductpdf'];
            $data['status'] = (isset($settings['status'])) ? $settings['status'] : false;
            $data['language_id'] = $this->config->get('config_language_id'); //HERE 
            $data['pdffile'] = HTTPS_SERVER . 'index.php?route=extension/module/siproductpdf/downloadproductpdf&product_id='.$product_id;
            return $this->load->view($this->modulePath, $data);
        }

错误信息

当启用$language = $this->config->get('config_language');时，出现如下致命错误：

Fatal error: Uncaught Error: Call to a member function get() on null in /home/coelhost/cls.pt/catalog/controller/extension/module/siproductpdf.php:17 Stack trace: #0 /home/coelhost/cls.pt/system/config/si/tcpdf/tcpdf.php(3541): OCPDF->Header() #1 /home/coelhost/cls.pt/system/config/si/tcpdf/tcpdf.php(3208): TCPDF->setHeader() #2 /home/coelhost/cls.pt/system/config/si/tcpdf/tcpdf.php(3120): TCPDF->startPage('', '', false) #3 /home/coelhost/cls.pt/catalog/controller/extension/module/siproductpdf.php(273): TCPDF->AddPage() #4 /home/coelhost/cls.pt/vqmod/vqcache/vq2-storage_modification_system_engine_action.php(79): ControllerExtensionModulesiproductpdf->downloadproductpdf() #5 /home/coelhost/cls.pt/catalog/controller/startup/router.php(25): Action->execute(Object(Registry)) #6 /home/coelhost/cls.pt/vqmod/vqcache/vq2-storage_modification_system_engine_action.php(79): ControllerStartupRouter->index() #7 /home/coelhost/cls.pt/vqmod/vqcache/vq2-storage_modification_system_engine_router.php(130): Action->execute(Object(Registry)) in /home/coelhost/cls.pt/catalog/controller/extension/module/siproductpdf.php on line 17

解决方案

问题根源

OCPDF类中直接调用$this->config或$this->session会报错，因为这些对象未注入到TCPDF子类中，导致调用get()方法时出现“Call to a member function get() on null”错误。

解决步骤

  1. 在控制器中获取当前语言
    在生成PDF的控制器方法（如downloadproductpdf）中，先获取网站选中的语言：
// 在downloadproductpdf方法内
$language = $this->config->get('config_language');
// 优先从session获取用户选中的语言
if (isset($this->session->data['language'])) {
    $language = $this->session->data['language'];
}
  1. 为OCPDF类添加语言设置方法
    修改OCPDF类，新增存储和设置语言的属性与方法：
class OCPDF extends TCPDF {
    private $language;

    public function setLanguage($lang) {
        $this->language = $lang;
    }

    // 其他原有方法...
}
  1. 在Header/Footer方法中使用已设置的语言
    修改Header和Footer方法，直接使用$this->language变量：
// 修改后的Header方法
public function Header() {
    $server = $this->request->server['HTTPS'] ? HTTP_SERVER : HTTPS_SERVER;  
    $language = $this->language;

    $logo_file = $server . 'image/catalog/pdftemplate/header.png';
    if ($language == 'en-gb') {
        $logo_file = $server . 'image/catalog/pdftemplate/header-en.png';
    } elseif ($language == 'es') {
        $logo_file = $server . 'image/catalog/pdftemplate/header-es.png';
    } elseif ($language == 'pt-pt') {
        $logo_file = $server . 'image/catalog/pdftemplate/header-pt.png';
    }

    $header_details_address = $this->header_details_address;
    $header_details_email = $this->header_details_email;
  
    $header_html = <<<EOD
<img src="$logo_file" height="190px">
<br/><br/><br/><br/>
EOD;

    $this->writeHTMLCell(0, 0, '', '', $header_html, 0, 1, 0, true, '', true);
}

// 修改后的Footer方法
public function Footer() {
    $this->SetY(-25);
    $this->SetFont('helvetica', 'I', 8);
    
    $server = $this->request->server['HTTPS'] ? HTTP_SERVER : HTTPS_SERVER;  
    $language = $this->language;
    
    $mlogo_file = $server . 'image/catalog/pdftemplate/footer.png';
    if ($language == 'en-gb') {
        $mlogo_file = $server . 'image/catalog/pdftemplate/footer-en.png';
    } elseif ($language == 'es') {
        $mlogo_file = $server . 'image/catalog/pdftemplate/footer-es.png';
    } elseif ($language == 'pt-pt') {
        $mlogo_file = $server . 'image/catalog/pdftemplate/footer-pt.png';
    }

    // 修复原代码中$footer_image_file未定义的错误
    $footer_logo_html = '<div style="width:100% !important;height:190px;"><img width="100%" src="' . $mlogo_file . '" /></div>';
    $this->writeHTMLCell(0, 0, '', '', $footer_logo_html, 0, 1, 0, true, 'C', true);
}
  1. 在控制器中实例化OCPDF并传递语言
// 在downloadproductpdf方法内
$pdf = new OCPDF();
$pdf->setLanguage($language);
// 执行其他PDF生成逻辑（添加内容、设置参数等）
$pdf->Output();

内容的提问来源于stack exchange，提问作者Diogo Amorim

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最近更新时间：2026.07.25 04:54:58