配置FedEx贸易文件上传API遇json_encode错误，求代码排查

问题描述 #

在配置FedEx贸易文件上传API时，遇到以下错误：

json_encode error: Type is not supported

请求负载的示例代码如下：

try{
      $document = [
        "workflowName"=> "ETDPostshipment",
        "carrierCode"=> "FDXE",
        "name"=> 'invoiceFileName',
        "contentType"=> 'application/pdf',
        "meta"=> [
          "shipDocumentType"=> "COMMERCIAL_INVOICE",
          "trackingNumber"=> "794988380825",
          "shipmentDate"=> "2024-02-26",
          "originCountryCode"=> "JP",
          "destinationCountryCode"=>  $country_code
        ]
      ];
      
      $body = [
        [
            'name' => 'document',
            'contents' => json_encode($document)
        ],
        [
            'name' => 'attachment',
            'contents' => fopen(public_path('storage/invoice/invoiceFileName'), 'r'),
            'filename' => $shipping['invoiceFileName']

        ]
      ];
      $response = $this->uploader->post($path, ['multipart' => $body]);
      $data = json_decode($response->getBody(), true);
      Log::info('Document uploaded successfully.', ['response' => $data]);
      return $data;
    }
    catch(RequestException $e){
      Log::error('Request Exception: ' . $e->getMessage(), ['code' => $e->getCode()]);
    }
    catch (Throwable $e){
      Log::error('Unexpected Exception: ' . $e->getMessage());
      return;
    }
  }

错误原因 #

1. 类型不兼容导致json_encode失败
   错误直接触发点是json_encode($document)，核心原因是$document['meta']['destinationCountryCode']对应的$country_code变量可能是非字符串类型（比如整数、未定义变量、对象），json_encode无法处理这类非预期类型的数据。

2. 文件路径与文件名不匹配
   fopen中使用的固定路径public_path('storage/invoice/invoiceFileName')和参数filename的$shipping['invoiceFileName']不一致，可能导致文件无法读取。

3. 缺少文件存在性检查
   未提前验证文件是否存在，若文件缺失会导致fopen返回false，进一步引发多部分请求的解析错误。

修正方案 #

修正后的代码 #

try{
    $document = [
        "workflowName" => "ETDPostshipment",
        "carrierCode" => "FDXE",
        "name" => 'invoiceFileName',
        "contentType" => 'application/pdf',
        "meta" => [
            "shipDocumentType" => "COMMERCIAL_INVOICE",
            "trackingNumber" => "794988380825",
            "shipmentDate" => "2024-02-26",
            "originCountryCode" => "JP",
            // 强制转换为字符串，确保类型符合要求
            "destinationCountryCode" => (string)$country_code
        ]
    ];
    
    // 拼接正确的文件路径，匹配filename参数
    $filePath = public_path('storage/invoice/' . $shipping['invoiceFileName']);
    
    // 提前检查文件是否存在且可读
    if (!file_exists($filePath) || !is_readable($filePath)) {
        Log::error('Invoice file not found or unreadable: ' . $filePath);
        return;
    }
    
    // 增加json_encode错误检查
    $docJson = json_encode($document);
    if (json_last_error() !== JSON_ERROR_NONE) {
        Log::error('JSON encode failed: ' . json_last_error_msg());
        return;
    }
    
    $body = [
        [
            'name' => 'document',
            'contents' => $docJson
        ],
        [
            'name' => 'attachment',
            'contents' => fopen($filePath, 'r'),
            'filename' => $shipping['invoiceFileName']
        ]
    ];
    
    $response = $this->uploader->post($path, ['multipart' => $body]);
    $data = json_decode($response->getBody(), true);
    Log::info('Document uploaded successfully.', ['response' => $data]);
    return $data;
}
catch(RequestException $e){
    Log::error('Request Exception: ' . $e->getMessage(), ['code' => $e->getCode()]);
}
catch (Throwable $e){
    Log::error('Unexpected Exception: ' . $e->getMessage());
    return;
}

额外检查项 #

• 确认$country_code变量已正确赋值，且为ISO 3166-1 alpha-2格式的字符串（如"US"、"CN"）
• 确保PHP进程拥有目标文件的读取权限
• 若使用Guzzle作为HTTP客户端，可手动关闭文件资源避免内存泄漏（Guzzle通常会自动处理）

内容的提问来源于stack exchange，提问作者Bipu Shrestha