如何在python中的itertools.islice（）函数中打开关闭的_io.TextIoWrapper对象？

Question

我尝试了一些脚本，我捕获pdf文件，然后将该文件转换为txt文件。我得到的文本文件类型为_io.textIoWrapper。现在我用_io.textIoWrapper对象调用itertools.isslice（）。如果文件格式的纯io.textIoWrapper没有给出任何错误，则生成ValueError: I/O operation on closed file.。我试图打开textIoWrapper对象，但结果是expect only str , bytes or None not TextIoWrapper type

views.py

    def save_file(cls, user, file, file_format, project_id,file1):
        project = get_object_or_404(Project, pk=project_id)
        parser = cls.select_parser(file_format)
        if file_format == 'pdf':
            path = default_storage.save('text_pdf_file.pdf', ContentFile(file.read()))
            return_file = convert_pdf_txt(path,file_format)
            print(type(return_file))  # _io.textIoWrapper
            file = return_file
        data = parser.parse(file,file_format)
        storage = project.get_storage(data)
        storage.save(user)

utils.py

class PlainTextParser(FileParser):

    def parse(self, file,file_format):

        if file_format == 'plain':
            file = EncodedIO(file)
            file = io.TextIOWrapper(file, encoding=file.encoding)

        while True:
            batch = list(itertools.islice(file, settings.IMPORT_BATCH_SIZE))
            if not batch:
                break
            yield [{'text': line.strip()} for line in batch]

convert.py

import os
from docx import Document
import pdfplumber as pp
import io
import unidecode
import re

def remove_accented_chars(text):
  text = unidecode.unidecode(text)
  return text

def remove_extra_spaces(line):
  return re.sub(' +|\t+',' ',line)

def remove_special_char(line):
  return re.sub(r"[^a-zA-Z0-9%.@]+",' ', line)

def preprocessing(lines,fileExtension):
    example_text_file = "ex_txt.txt"
    for line in lines:
        if fileExtension == "docx":
            x=str(line.text)
        elif fileExtension == "pdf":
            x = line.extract_text()
        else:
            x = line
        x=remove_accented_chars(x)
        x=remove_extra_spaces(x)
        x=remove_special_char(x)
        with open(example_text_file,"a+",) as pre:
            if len(x)>=5:
                pre.write(x+"\n")
    return pre


def convert_pdf_txt(path,fileExtension):
    with pp.open(path) as pdf :
        pages = pdf.pages
        pre = preprocessing(pages,fileExtension)
        return pre