javascript - Flask：删除 @after_this_request 装饰器中的文件不起作用。文件正被另一个进程使用

Question

嗨，我想下载一个 zip 文件，然后在下载完成后将其删除。

@app.route('/download',methods=['GET', 'POST'])
def download():
    projectTitle = request.args.get('projectTitle')
    file_path = projectTitle+".zip"

    @after_this_request
    def remove_file(response):
        print("After this request...")
        os.remove(file_path)
        return response

    return send_file(file_path,
                 mimetype='application/zip',
                 attachment_filename=file_path,
                 as_attachment=True)

我用 javascript 调用这个端点：

function downloadURI(uri) 
{
    var link = document.createElement("a");
    link.href = uri;
    link.target = "_blank";
    link.click();
}

downloadURI("download?projectTitle="+title);

zip文件永远不会被删除，我错过了什么？


编辑：我调试了一下，我注意到我收到以下错误：

After this request...
After this request...
[2020-07-10 13:00:40,653] ERROR in app: Exception on /download [GET]
Traceback (most recent call last):
  File "C:\Users\ceccolig\PycharmProjects\SingleBP\venv\lib\site-packages\flask\app.py", line 2447, in wsgi_app
    response = self.full_dispatch_request()
  File "C:\Users\ceccolig\PycharmProjects\SingleBP\venv\lib\site-packages\flask\app.py", line 1953, in full_dispatch_request
    return self.finalize_request(rv)
  File "C:\Users\ceccolig\PycharmProjects\SingleBP\venv\lib\site-packages\flask\app.py", line 1970, in finalize_request
    response = self.process_response(response)
  File "C:\Users\ceccolig\PycharmProjects\SingleBP\venv\lib\site-packages\flask\app.py", line 2267, in process_response
    response = handler(response)
  File "C:/Users/ceccolig/PycharmProjects/SingleBP/app.py", line 39, in remove_file
    os.remove(file_path)
PermissionError: [WinError 32] The process cannot access the file because it is being used by another process: 'DemoTMD-prod.zip'
[2020-07-10 13:00:40,656] ERROR in app: Request finalizing failed with an error while handling an error
Traceback (most recent call last):
  File "C:\Users\ceccolig\PycharmProjects\SingleBP\venv\lib\site-packages\flask\app.py", line 2447, in wsgi_app
    response = self.full_dispatch_request()
  File "C:\Users\ceccolig\PycharmProjects\SingleBP\venv\lib\site-packages\flask\app.py", line 1953, in full_dispatch_request
    return self.finalize_request(rv)
  File "C:\Users\ceccolig\PycharmProjects\SingleBP\venv\lib\site-packages\flask\app.py", line 1970, in finalize_request
    response = self.process_response(response)
  File "C:\Users\ceccolig\PycharmProjects\SingleBP\venv\lib\site-packages\flask\app.py", line 2267, in process_response
    response = handler(response)
  File "C:/Users/ceccolig/PycharmProjects/SingleBP/app.py", line 39, in remove_file
    os.remove(file_path)
PermissionError: [WinError 32] The process cannot access the file because it is being used by another process: 'DemoTMD-prod.zip'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\ceccolig\PycharmProjects\SingleBP\venv\lib\site-packages\flask\app.py", line 1970, in finalize_request
    response = self.process_response(response)
  File "C:\Users\ceccolig\PycharmProjects\SingleBP\venv\lib\site-packages\flask\app.py", line 2267, in process_response
    response = handler(response)
  File "C:/Users/ceccolig/PycharmProjects/SingleBP/app.py", line 39, in remove_file
    os.remove(file_path)
PermissionError: [WinError 32] The process cannot access the file because it is being used by another process: 'DemoTMD-prod.zip'
127.0.0.1 - - [10/Jul/2020 13:00:40] "GET /download?projectTitle=DemoTMD-prod HTTP/1.1" 500 -

如您所见，@after_this_request 被调用了两次（我不知道为什么），实际上“在此请求之后”被打印了两次。

标签： javascriptpythonflaskrequest

Answer 1

如你所见，当被@after_this_request装饰的方法调用时，这个请求生命还没有结束，客户端还在等待响应，所以文件还在打开，或者你可以说它正在被使用，所以你不能删除文件。

好吧，这是我的解决方案。就像：

from stuff import celery_app


@celery_app.task(queue='some_specific_queue')
def delete_files(filepath):
    try:
        os.remove(filepath)
    except FileNotFoundError:
        # some other stuff

而在你的api中，你可以像这样发布这个任务：</p>

import datetime


@app.route('/download',methods=['GET', 'POST'])
def download():
    projectTitle = request.args.get('projectTitle')
    file_path = projectTitle+".zip"

    delete_files.apply_async(
        args=(file_path), 
        eta=datetime.datetime.utcnow()+datetime.timedelta(hours=4)
    )

    return send_file(file_path,
                 mimetype='application/zip',
                 attachment_filename=file_path,
                 as_attachment=True)

我不知道怎么对人...