Python瓶没有返回cookie/ValueError：查看功能没有返回响应

Question

我仍在努力将Python中的字符串传递给另一个函数。

我试图按照这里给出的例子：https://www.tutorialspoint.com/flask/flask_cookies.htm

我已经试过落实到我的代码，这但现在我得到以下回溯：

Traceback (most recent call last): 
    File "/Users/marcel/tensorflow/lib/python3.6/site-packages/flask/app.py", line 1982, in wsgi_app 
    response = self.full_dispatch_request() 
    File "/Users/marcel/tensorflow/lib/python3.6/site-packages/flask/app.py", line 1615, in full_dispatch_request 
    return self.finalize_request(rv) 
    File "/Users/marcel/tensorflow/lib/python3.6/site-packages/flask/app.py", line 1630, in finalize_request 
    response = self.make_response(rv) 
    File "/Users/marcel/tensorflow/lib/python3.6/site-packages/flask/app.py", line 1725, in make_response 
    raise ValueError('View function did not return a response') 
ValueError: View function did not return a response 

这将意味着我我没有返回任何东西，但我真的不知道我要去哪里错了，我不得不承认我很迷茫。

我完整的代码看起来是这样的：

from __future__ import print_function 
import tensorflow as tf 
import argparse 
import os 
from six.moves import cPickle 
from model import Model 
from six import text_type 
import flask 
from flask import jsonify, render_template, request, make_response 

app = flask.Flask(__name__) 


@app.route('/') 
def index(): 
    return render_template('index.html') 

@app.route('/test') 
def tester(): 
    return "This is a test" 

@app.route('/', methods = ['POST', 'GET']) 
def main(): 
    if request.method == 'POST': 
     parser = argparse.ArgumentParser(
          formatter_class=argparse.ArgumentDefaultsHelpFormatter) 
     parser.add_argument('--save_dir', type=str, default='save', 
          help='model directory to store checkpointed models') 
     parser.add_argument('-n', type=int, default=500, 
          help='number of characters to sample') 
     parser.add_argument('--prime', type=text_type, default=u' ', 
          help='prime text') 
     parser.add_argument('--sample', type=int, default=1, 
          help='0 to use max at each timestep, 1 to sample at ' 
           'each timestep, 2 to sample on spaces') 

     args = parser.parse_args() 

     resp = make_response(render_template('sample.html')) 
     resp.set_cookie('args', args) 

     return resp 


@app.route('/sampler', methods = ['POST', 'GET']) 
def sample(): 
    args = request.cookies.get('args') 
    with open(os.path.join(args.save_dir, 'config.pkl'), 'rb') as f: 
     saved_args = cPickle.load(f) 
    with open(os.path.join(args.save_dir, 'chars_vocab.pkl'), 'rb') as f: 
     chars, vocab = cPickle.load(f) 
    model = Model(saved_args, training=False) 
    with tf.Session() as sess: 
     tf.global_variables_initializer().run() 
     saver = tf.train.Saver(tf.global_variables()) 
     ckpt = tf.train.get_checkpoint_state(args.save_dir) 
     if ckpt and ckpt.model_checkpoint_path: 
      saver.restore(sess, ckpt.model_checkpoint_path) 
      if request.method == 'POST': 
       text = model.sample(sess, chars, vocab, args.n, args.prime, 
            args.sample).encode('utf-8') 
       resp = make_response(render_template('text.html')) 
       resp.set_cookie('verse', text) 
       return resp 


@app.route('/text') 
def printer():  
    verse = request.cookies.get('verse') 
    return verse 


@app.errorhandler(404) 
def page_not_found(error): 
    return render_template('404.html'), 404 

if __name__ == '__main__': 
    main() 

之前，我曾试图刚刚从我的样本功能打印机功能发送Cookie，但它返回相同的错误。

我的代码之前：

def sample(args): 
    with open(os.path.join(args.save_dir, 'config.pkl'), 'rb') as f: 
     saved_args = cPickle.load(f) 
    with open(os.path.join(args.save_dir, 'chars_vocab.pkl'), 'rb') as f: 
     chars, vocab = cPickle.load(f) 
    model = Model(saved_args, training=False) 
    with tf.Session() as sess: 
     tf.global_variables_initializer().run() 
     saver = tf.train.Saver(tf.global_variables()) 
     ckpt = tf.train.get_checkpoint_state(args.save_dir) 
     if ckpt and ckpt.model_checkpoint_path: 
      saver.restore(sess, ckpt.model_checkpoint_path) 
      text = model.sample(sess, chars, vocab, args.n, args.prime, 
           args.sample).encode('utf-8') 
      resp = make_response(render_template('text.html')) 
      resp.set_cookie('verse', text) 
      return resp 


@app.route('/text') 
def printer():  
    verse = request.cookies.get('verse') 
    return verse 

Answer 1

当verse cookie的值不存在的价值verse变量将变为None。这意味着您的text视图将返回None，其中Flask不喜欢并理解为“视图函数未返回响应”。

您可能需要妥善处理这种情况下 - 例如，简单地返回一个空字符串会解决这个问题（当然，这只是一个样本简单的解决方法来证明的差异）：

@app.route('/text') 
def printer():  
    return request.cookies.get('verse', '') 

而且，并非sample()视图中的所有代码路径都会返回有效的响应 - 请确保解决该问题（例如，向sample()视图发出GET请求会导致相同的“视图函数未返回响应”错误） 。

Answer 2

在main，你将需要外部的请求参数校验范围返回值：

@app.route('/', methods = ['POST', 'GET']) 
def main(): 
    if request.method == 'POST': 
     parser = argparse.ArgumentParser(
     ....#statements follow    
     args = parser.parse_args() 

     resp = make_response(render_template('sample.html')) 
     resp.set_cookie('args', args) 

     return resp 
    return render_template('home.html') #need to return something here