Question

我创建了一个flask网站，使表单及其相应结果显示在同一页面上。我遇到的问题是，当我第一次执行MPVolumeView.showsRouteButton并加载网站时，第一次单击“提交”按钮时，出现以下关键错误：

flask run

但是，如果我第二次单击提交按钮，则结果将正常显示。甚至更奇怪的是，如果我不杀掉flask应用程序，而只是在网页上进行一次硬刷新，然后再次提交表单，这一次，结果只显示一次单击，而不是两次。

如何获取它，以便如果我刚刚启动了flask应用程序，只需单击一次提交即可显示结果？

源代码

app.py：

127.0.0.1 - - [12/Jun/2019 14:40:11] "GET / HTTP/1.1" 200 -
127.0.0.1 - - [12/Jun/2019 14:40:11] "GET /static/favicon.ico HTTP/1.1" 200 -
127.0.0.1 - - [12/Jun/2019 14:40:16] "POST /process_file HTTP/1.1" 200 -
127.0.0.1 - - [12/Jun/2019 14:40:16] "GET /upload_vals?payload=%7B%22affiliation%22%3A%22number%22%2C%22period%22%3A%22no%22%2C%22space%22%3A%22no%22%7D HTTP/1.1" 500

  File "/Users/cdastmalchi/Desktop/author_script/app.py", line 106, in upload_vals
    proc = subprocess.Popen('python author_script.py {} -p {} -s {} -m {}'.format(flask.session['filename'], 'y' if payload['period'] == 'yes' else 'n', 'y' if payload['space'] == 'yes' else 'n', payload['affiliation'][:3]), shell=True, stdout=subprocess.PIPE)
  File "/Users/cdastmalchi/miniconda2/lib/python2.7/site-packages/werkzeug/local.py", line 378, in <lambda>
    __getitem__ = lambda x, i: x._get_current_object()[i]
  File "/Users/cdastmalchi/miniconda2/lib/python2.7/site-packages/flask/sessions.py", line 83, in __getitem__
    return super(SecureCookieSession, self).__getitem__(key)
KeyError: 'filename'

index.html：

TEMPLATE_FILE = 'ExampleAuthorList.txt'
UPLOAD_FOLDER = '.'
ALLOWED_EXTENSIONS = set(['txt'])

app = flask.Flask(__name__)

app.config['TEMPLATE_FILE'] = TEMPLATE_FILE
app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER
app.secret_key = ''.join(random.choice(string.ascii_letters) for _ in range(20)) #needed to use flask.session

@app.route('/', methods=['GET'])
def home():
   return flask.render_template('index.html')

@app.route('/process_file', methods=['POST'])
def process_file():
  #here, you can run all the checks as before, but instead of flash, you can return jsonified results to read in the front-end
    if 'file' not in flask.request.files or not flask.request.files['file'].filename:
        return flask.jsonify({'result':'False', 'message':'no files selected'})
        return flask.redirect(url_for('home'))
    file = flask.request.files['file']
    filename = secure_filename(file.filename)
    if not allowed_file(file.filename):
        return flask.jsonify({'result':'False', 'message':'Must be TXT file!'})
        return flask.redirect(url_for('home'))
    if not places_exist(os.path.join(app.config['UPLOAD_FOLDER'], filename)):
        return flask.jsonify({'result':'False', 'message':'There is an affiliation missing from your Place list. Please re-try.'})
        return flask.redirect(url_for('home'))
    file.save(os.path.join(app.config['UPLOAD_FOLDER'], filename))
    flask.session['filename'] = filename
    return flask.jsonify({'result':'True'})

@app.route('/upload_vals')
def upload_vals():
    payload = json.loads(flask.request.args.get('payload'))
    proc = subprocess.Popen('python author_script.py {} -p {} -s {} -m {}'.format(flask.session['filename'], 'y' if payload['period'] == 'yes' else 'n', 'y' if payload['space'] == 'yes' else 'n', payload['affiliation'][:3]), shell=True, stdout=subprocess.PIPE)
    while proc.poll() is None:
        time.sleep(0.5)
    with open("templates/authorList.html") as f:
        data = ''.join(f.readlines())
    return flask.jsonify({'data':data})

Answer 1

错误表明filename键不在session中（至少在第一次通话后）。

如果我想的没错，解决方案应该是：

def process_file():

    ...
    flask.session['filename'] = filename
    flask.session.modified = True

    return ...

仅当我单击“提交”按钮两次时，才会显示表单结果

1 个答案: