使用Python 3.10.6+Camelot读取PDF特定表格时崩溃求助

问题详情 #

• Python版本：3.10.6
• 需求：读取PDF中第24、26页的表格，仅成功读取第21-23页和第25页的表格
• 表格差异：无法读取的表格第二行为单列，可读取的表格第二行为多列
• 核心报错：ValueError: Data must be padded to 16 byte boundary in CBC mode，但确认PDF未设置加密
• PDF来源：由Microsoft Office Professional Plus 2019的Word生成

所用代码 #

tables = camelot.read_pdf( 
    cFile,
    pages=str(24),
    password=None,
    flavor='lattice',
    flag_size=True,
    strip_text='\n'
    # 已尝试的注释参数均无效：
    # , backend='poppler'
    # , process_background=True
    # , table_areas=['36,731,576,396']
    # , table_regions=['36,731,576,396']
    # , edge_tol=200
    # , row_tol=10
    # , line_scale=40
    # , shift_text=['r', 'b']
    # , copy_text=['h']
)

完整报错信息 #

Traceback (most recent call last):
  File "G:\My Drive\Bugs\15888 - Convert PDF table data to Oracle data\Test Table 9.py", line 58, in <module>
    tables = camelot.read_pdf( cFile
  File "C:\Users\56663\AppData\Roaming\Python\Python310\site-packages\camelot\io.py", line 113, in read_pdf
    tables = p.parse(
  File "C:\Users\56663\AppData\Roaming\Python\Python310\site-packages\camelot\handlers.py", line 172, in parse
    self._save_page(self.filepath, p, tempdir)
  File "C:\Users\56663\AppData\Roaming\Python\Python310\site-packages\camelot\handlers.py", line 120, in _save_page
    outfile.write(f)
  File "C:\Users\56663\AppData\Roaming\Python\Python310\site-packages\PyPDF2\_writer.py", line 839, in write
    self.write_stream(stream)
  File "C:\Users\56663\AppData\Roaming\Python\Python310\site-packages\PyPDF2\_writer.py", line 812, in write_stream
    self._sweep_indirect_references(self._root)
  File "C:\Users\56663\AppData\Roaming\Python\Python310\site-packages\PyPDF2\_writer.py", line 961, in _sweep_indirect_references
    data = self._resolve_indirect_object(data)
  File "C:\Users\56663\AppData\Roaming\Python\Python310\site-packages\PyPDF2\_writer.py", line 1006, in _resolve_indirect_object
    real_obj = data.pdf.get_object(data)
  File "C:\Users\56663\AppData\Roaming\Python\Python310\site-packages\PyPDF2\_reader.py", line 1160, in get_object
    retval = self._encryption.decrypt_object(
  File "C:\Users\56663\AppData\Roaming\Python\Python310\site-packages\PyPDF2\_encryption.py", line 744, in decrypt_object
    return cf.decrypt_object(obj)
  File "C:\Users\56663\AppData\Roaming\Python\Python310\site-packages\PyPDF2\_encryption.py", line 185, in decrypt_object
    obj[dictkey] = self.decrypt_object(value)
  File "C:\Users\56663\AppData\Roaming\Python\Python310\site-packages\PyPDF2\_encryption.py", line 179, in decrypt_object
    data = self.strCrypt.decrypt(obj.original_bytes)
  File "C:\Users\56663\AppData\Roaming\Python\Python310\site-packages\PyPDF2\_encryption.py", line 87, in decrypt
    d = aes.decrypt(data)
  File "C:\Users\56663\AppData\Roaming\Python\Python310\site-packages\Crypto\Cipher\_mode_cbc.py", line 246, in decrypt
    raise ValueError("Data must be padded to %d byte boundary in CBC mode" % self.block_size)
ValueError: Data must be padded to 16 byte boundary in CBC mode

解决方案建议 #

• 修复PDF结构：用Adobe Acrobat或其他专业PDF工具打开原文件，选择「另存为」重新生成PDF，修复Word导出时可能产生的字节对齐异常。
• 强制使用Poppler后端：确保已安装Poppler（Windows需将其路径添加到系统环境变量），然后在代码中启用backend='poppler'参数，跳过PyPDF2的解密逻辑。
• 提前提取目标页面：先用PyPDF2提取第24、26页到临时PDF，再用Camelot读取临时文件：

  from PyPDF2 import PdfReader, PdfWriter
  
  # 提取目标页面到临时文件
  reader = PdfReader(cFile)
  writer = PdfWriter()
  for page_idx in [23,25]:  # PyPDF2页面索引从0开始
      writer.add_page(reader.pages[page_idx])
  
  temp_pdf = "temp_target_pages.pdf"
  with open(temp_pdf, "wb") as f:
      writer.write(f)
  
  # 读取临时PDF的表格
  tables = camelot.read_pdf(
      temp_pdf,
      pages="1,2",
      flavor='lattice',
      flag_size=True,
      strip_text='\n'
  )
  

• 切换到Stream模式：对结构特殊的表格，尝试flavor='stream'，配合table_areas参数精确定位表格区域。
• 升级依赖库：更新PyPDF2、Camelot及加密相关库到最新版本，修复已知bug：

  pip install --upgrade pypdf2 camelot-py[base] pycryptodome
  

内容的提问来源于stack exchange，提问作者Gary Crockett