的Python瓶ValueError異常：查看功能並沒有返回響應

Question

這是我的瓶代碼：

from flask import Flask 
from flask import request 

app = Flask(__name__) 

@app.route('/', methods=['GET', 'POST']) 
def signal(): 
    if request.method == 'POST': 
     content = request.get_json() 
     return content 
    else: 
     return 'Hello, world!' 

if __name__ == '__main__': 
    app.run(debug=True) 

我運行這個HTTP後（從同一臺機器）：

import requests 
import json 
dump= '{"on":"true"}' 
r = requests.post('http://127.0.0.1:5000', dump) 

而且收到此錯誤：

[2017-03-04 14:18:35,250] ERROR in app: Exception on/[POST] 
Traceback (most recent call last): 
File "c:\users\andrew\appdata\local\programs\python\python35-32\lib\site-packages\flask\app.py", line 1982, in wsgi_app 
response = self.full_dispatch_request() 
File "c:\users\andrew\appdata\local\programs\python\python35-32\lib\site-packages\flask\app.py", line 1615, in full_dispatch_request 
return self.finalize_request(rv) 
File "c:\users\andrew\appdata\local\programs\python\python35-32\lib\site-packages\flask\app.py", line 1630, in finalize_request 
response = self.make_response(rv) 
File "c:\users\andrew\appdata\local\programs\python\python35-32\lib\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 

任何想法，爲什麼發生這種情況？從一開始我就在網上閱讀，我認爲這是因爲我沒有其他的東西，因爲它是一個GET，但我現在無法理解。

Answer 1

如果您正在測試直接返回您的POST請求的有效載荷，你應該做的jsonify和瓶有這個UTIL功能

from flask import Flask 
from flask import request, jsonify 

app = Flask(__name__) 

@app.route('/', methods=['GET', 'POST']) 
def signal(): 
    if request.method == 'POST': 
     content = request.get_json() 
     return jsonify(content) 
    else: 
     return 'Hello, world!' 

if __name__ == '__main__': 
    app.run(debug=True) 

然後在你的測試代碼，添加Content-Type爲標題，（不這樣做，request.get_json()韓元」 t工作）：

dump = '{"on":"true"}' 
r = requests.post('http://127.0.0.1:5000', data=dump, 
        headers={'Content-Type': 'application/json'}) 

Answer 2

看起來像問題是與您的腳本是向您的應用程序提出請求問題。試着用捲曲，像下面：

$ curl -H "Content-type: application/json" -X POST http://127.0.0.1:5000 -d '{"on":"true"}' 

你會得到迴應如下：

{ 
    "on": "true" 
} 

你的代碼（添加jsonify）看起來應該如下：

from flask import Flask 
from flask import request,jsonify 

app = Flask(__name__) 

@app.route('/', methods=['GET', 'POST']) 
def signal(): 
    if request.method == 'POST': 
     content = request.json 
     return jsonify(content) 
    else: 
     return 'Hello, world!' 

if __name__ == '__main__': 
    app.run(debug=True)