Django用户上传加密文件下载及下载后删除功能问题求助

问题说明 #

基于Django开发的文件加密解密网站，已实现文件上传加密功能，但存在两个问题：

• 无法下载media目录中保存的加密文件
• 需要实现文件下载完成后自动删除的功能

现有代码 #

models.py #

from django.db import models
import os

class Fileupload(models.Model):
    file = models.FileField(upload_to='media')
    date = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.file  # 错误：返回FileField对象而非字符串
    def filename(self):
        return os.path.basename(self.file.name)

views.py #

from msilib.schema import File
from urllib import response
from django.shortcuts import render,HttpResponse
from .models import Fileupload
from .encryptfile import encrypt

import os
from cryptography.fernet import Fernet
import mimetypes

def base(request):
    if request.method == 'POST':
        file2 = request.FILES["file"]
        document = Fileupload.objects.create(file=file2)
        document.save()
        fname = Fileupload.filename(document)
        global path1 
        path1 = "media/"+fname

        # 加密逻辑存在错误
        key = Fernet.generate_key()
        with open("thekey.key","wb") as thekey:
            thekey.write(key)
        
        with open(path1, 'rb') as file:
            original = file2.read()  # 错误：应读取本地保存的文件而非上传的临时文件
            
        encrypted = Fernet(key).encrypt(original)
        with open(path1, 'wb') as encrypted_file:
            encrypted_file.write(encrypted)
        
        return render(request,'download.html')
    else:
        return render(request, 'base.html')

def download(request):
    BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
    # filename未定义
    filepath = BASE_DIR + '/media/' + filename
    path1 = open(filepath, 'r')  # 错误：二进制文件需用rb模式
    mime_type, _ = mimetypes.guess_type(filepath)
    response = HttpResponse(path, content_type=mime_type)  # 错误：变量名应为path1
    response['Content-Disposition'] = "attachment; filename=%s" % filename
    return render(request, response,'base.html')  # 错误：不应使用render返回文件响应

def decrypt(request):
    return render(request, 'decrypt.html')

urls.py #

from django.contrib import admin
from django.urls import path
from Home import views
from django.conf.urls.static import static
from django.conf import settings

urlpatterns = [
    path('admin/', admin.site.urls),
    path('download',views.download,name='download'),
    path('decrypt',views.decrypt,name='decrypt'),
    path('',views.base,name='base'),
] + static(settings.MEDIA_URL,document_root=settings.MEDIA_ROOT) 

download.html #

<section class="u-align-center u-clearfix u-image u-shading u-section-1" 
      src="static/img/bghack.jpg" data-image-width="7395" data-image-height="4933" id="sec-f710">
    <div class="u-clearfix u-sheet u-sheet-1">
        <h1 class="u-text u-text-default u-title u-text-1">ENCRYPTION OF FILES</h1>
        <p class="u-large-text u-text u-text-default u-text-variant u-text-2">The file has been encrypted. Download the file by clicking the button below.</p>
        {% if url %}
        <div class = "download">
            <a href="{{ url }}" type="button" download class="u-btn u-button-style u-palette-2-base u-btn-1">Download the file</a>
        </div>
        {% endif %}
    </div>
</section>

修复方案 #

1. 修复文件下载功能 #

核心修改点：

• 移除全局变量，改用session传递文件ID
• 修正文件读取模式为二进制rb
• 直接返回HttpResponse作为文件响应
• 修正加密逻辑中读取文件的错误

修改后的代码：

models.py（修正__str__方法）

from django.db import models
import os

class Fileupload(models.Model):
    file = models.FileField(upload_to='media')
    date = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.file.name  # 返回文件路径字符串
    def filename(self):
        return os.path.basename(self.file.name)

views.py（重写base和download视图）

from django.shortcuts import render,HttpResponse
from .models import Fileupload

import os
from cryptography.fernet import Fernet
import mimetypes

def base(request):
    if request.method == 'POST':
        file2 = request.FILES["file"]
        document = Fileupload.objects.create(file=file2)
        document.save()
        fname = document.filename()
        file_path = document.file.path

        # 修正加密逻辑：读取本地已保存的文件
        key = Fernet.generate_key()
        with open("thekey.key","wb") as thekey:
            thekey.write(key)
        
        with open(file_path, 'rb') as file:
            original = file.read()
            
        encrypted = Fernet(key).encrypt(original)
        with open(file_path, 'wb') as encrypted_file:
            encrypted_file.write(encrypted)
        
        # 将文件ID存入session，供下载视图使用
        request.session['file_id'] = document.id
        # 传递文件名到下载页面
        return render(request,'download.html', {'file_name': fname})
    else:
        return render(request, 'base.html')

def download(request):
    # 从session获取文件ID
    file_id = request.session.get('file_id')
    if not file_id:
        return HttpResponse("无可用下载文件", status=404)
    
    try:
        document = Fileupload.objects.get(id=file_id)
        file_path = document.file.path
        
        # 二进制读取加密文件
        with open(file_path, 'rb') as f:
            content_type = mimetypes.guess_type(file_path)[0] or 'application/octet-stream'
            response = HttpResponse(f.read(), content_type=content_type)
            response['Content-Disposition'] = f'attachment; filename="{document.filename()}"'
            
            # 下载完成后自动删除文件及数据库记录
            def cleanup(response):
                if os.path.exists(file_path):
                    os.remove(file_path)
                document.delete()
                del request.session['file_id']  # 清除session中的文件ID
            
            response.close = cleanup
            return response
    except Fileupload.DoesNotExist:
        return HttpResponse("文件不存在", status=404)

def decrypt(request):
    return render(request, 'decrypt.html')

download.html（修改下载按钮路由）

<section class="u-align-center u-clearfix u-image u-shading u-section-1" 
      src="static/img/bghack.jpg" data-image-width="7395" data-image-height="4933" id="sec-f710">
    <div class="u-clearfix u-sheet u-sheet-1">
        <h1 class="u-text u-text-default u-title u-text-1">文件已加密完成</h1>
        <p class="u-large-text u-text u-text-default u-text-variant u-text-2">文件已加密，点击下方按钮下载。</p>
        <div class="download">
            <a href="{% url 'download' %}" class="u-btn u-button-style u-palette-2-base u-btn-1">下载文件</a>
        </div>
    </div>
</section>

2. 实现下载完成后自动删除 #

上述download视图中，通过给HttpResponse的close方法绑定清理函数，在响应完成（即文件下载完成）后自动执行以下操作：

• 删除本地文件
• 删除数据库中的Fileupload记录
• 清除session中的文件ID，避免重复下载

内容的提问来源于stack exchange，提问作者NEERAJ S