问题：如何在Flask中获取POST JSON？
我正在尝试使用Flask构建一个简单的API，现在我想在其中读取一些POSTed JSON。我使用Postman Chrome扩展程序执行POST，而我发布的JSON就是{"text":"lalala"}。我尝试使用以下方法读取JSON：
@app.route('/api/add_message/<uuid>', methods=['GET', 'POST'])
def add_message(uuid):
content = request.json
print content
return uuid
在浏览器上，它可以正确返回我放入GET中的UUID，但是在控制台上，它只是打印出来None（我希望它可以在其中打印出来{"text":"lalala"}。有人知道我如何从Flask方法中获取发布的JSON吗？
I’m trying to build a simple API using Flask, in which I now want to read some POSTed JSON. I do the POST with the Postman Chrome extension, and the JSON I POST is simply {"text":"lalala"}. I try to read the JSON using the following method:
@app.route('/api/add_message/<uuid>', methods=['GET', 'POST'])
def add_message(uuid):
content = request.json
print content
return uuid
On the browser it correctly returns the UUID I put in the GET, but on the console, it just prints out None (where I expect it to print out the {"text":"lalala"}. Does anybody know how I can get the posted JSON from within the Flask method?
回答 0
首先，该.json属性是一个委托给request.get_json()method的属性，该属性记录了为什么None在此处看到。
您需要将请求内容类型设置为，application/json以使.json属性和.get_json()方法（不带参数）起作用，None否则两者都会产生这种情况。请参阅Flask Request文档：
如果mimetype表示JSON（包含application / json，请参见is_json()），则它将包含已解析的JSON数据，否则为None。
您可以request.get_json()通过向其传递force=True关键字参数来告知跳过内容类型要求。
请注意，如果此时引发异常（可能导致400 Bad Request响应），则您的JSON 数据无效。它在某种程度上畸形；您可能需要使用JSON验证程序进行检查。
First of all, the .json attribute is a property that delegates to the request.get_json() method, which documents why you see None here.
You need to set the request content type to application/json for the .json property and .get_json() method (with no arguments) to work as either will produce None otherwise. See the Flask Request documentation:
This will contain the parsed JSON data if the mimetype indicates JSON (application/json, see is_json()), otherwise it will be None.
You can tell request.get_json() to skip the content type requirement by passing it the force=True keyword argument.
Note that if an exception is raised at this point (possibly resulting in a 400 Bad Request response), your JSON data is invalid. It is in some way malformed; you may want to check it with a JSON validator.
回答 1
作为参考，以下是有关如何从Python客户端发送json的完整代码：
import requests
res = requests.post('http://localhost:5000/api/add_message/1234', json={"mytext":"lalala"})
if res.ok:
print res.json()
“ json =“输入将自动设置内容类型，如下所述：使用Python请求发布JSON
以上客户端将使用此服务器端代码：
from flask import Flask, request, jsonify
app = Flask(__name__)
@app.route('/api/add_message/<uuid>', methods=['GET', 'POST'])
def add_message(uuid):
content = request.json
print content['mytext']
return jsonify({"uuid":uuid})
if __name__ == '__main__':
app.run(host= '0.0.0.0',debug=True)
For reference, here’s complete code for how to send json from a Python client:
import requests
res = requests.post('http://localhost:5000/api/add_message/1234', json={"mytext":"lalala"})
if res.ok:
print res.json()
The “json=” input will automatically set the content-type, as discussed here: Post JSON using Python Requests
And the above client will work with this server-side code:
from flask import Flask, request, jsonify
app = Flask(__name__)
@app.route('/api/add_message/<uuid>', methods=['GET', 'POST'])
def add_message(uuid):
content = request.json
print content['mytext']
return jsonify({"uuid":uuid})
if __name__ == '__main__':
app.run(host= '0.0.0.0',debug=True)
回答 2
这就是我要做的方法，应该是
@app.route('/api/add_message/<uuid>', methods=['GET', 'POST'])
def add_message(uuid):
content = request.get_json(silent=True)
# print(content) # Do your processing
return uuid
随着silent=True集，该get_json功能将尝试检索JSON的身体的时候默默的失败。默认情况下，此设置为False。如果您始终希望使用json正文（而不是可选），请将其保留为silent=False。
设置force=True将忽略request.headers.get('Content-Type') == 'application/json'烧瓶对您的
检查。默认情况下，它也设置为False。
请参见烧瓶文档。
我强烈建议您离开force=False并让客户端发送Content-Type标头以使其更加明确。
希望这可以帮助！
This is the way I would do it and it should be
@app.route('/api/add_message/<uuid>', methods=['GET', 'POST'])
def add_message(uuid):
content = request.get_json(silent=True)
# print(content) # Do your processing
return uuid
With silent=True set, the get_json function will fail silently when trying to retrieve the json body. By default this is set to False. If you are always expecting a json body (not optionally), leave it as silent=False.
Setting force=True will ignore the
request.headers.get('Content-Type') == 'application/json' check that flask does for you. By default this is also set to False.
See flask documentation.
I would strongly recommend leaving force=False and make the client send the Content-Type header to make it more explicit.
Hope this helps!
回答 3
假设您已发布具有application/json内容类型的有效JSON ，request.json将具有已解析的JSON数据。
from flask import Flask, request, jsonify
app = Flask(__name__)
@app.route('/echo', methods=['POST'])
def hello():
return jsonify(request.json)
Assuming you’ve posted valid JSON with the application/json content type, request.json will have the parsed JSON data.
from flask import Flask, request, jsonify
app = Flask(__name__)
@app.route('/echo', methods=['POST'])
def hello():
return jsonify(request.json)
回答 4
对于所有问题都是来自ajax调用的人，这里有一个完整的示例：
Ajax调用：这里的关键是使用a dict然后JSON.stringify
var dict = {username : "username" , password:"password"};
$.ajax({
type: "POST",
url: "http://127.0.0.1:5000/", //localhost Flask
data : JSON.stringify(dict),
contentType: "application/json",
});
在服务器端：
from flask import Flask
from flask import request
import json
app = Flask(__name__)
@app.route("/", methods = ['POST'])
def hello():
print(request.get_json())
return json.dumps({'success':True}), 200, {'ContentType':'application/json'}
if __name__ == "__main__":
app.run()
For all those whose issue was from the ajax call, here is a full example :
Ajax call : the key here is to use a dict and then JSON.stringify
var dict = {username : "username" , password:"password"};
$.ajax({
type: "POST",
url: "http://127.0.0.1:5000/", //localhost Flask
data : JSON.stringify(dict),
contentType: "application/json",
});
And on server side :
from flask import Flask
from flask import request
import json
app = Flask(__name__)
@app.route("/", methods = ['POST'])
def hello():
print(request.get_json())
return json.dumps({'success':True}), 200, {'ContentType':'application/json'}
if __name__ == "__main__":
app.run()
回答 5
给出另一种方法。
from flask import Flask, jsonify, request
app = Flask(__name__)
@app.route('/service', methods=['POST'])
def service():
data = json.loads(request.data)
text = data.get("text",None)
if text is None:
return jsonify({"message":"text not found"})
else:
return jsonify(data)
if __name__ == '__main__':
app.run(host= '0.0.0.0',debug=True)
To give another approach.
from flask import Flask, jsonify, request
app = Flask(__name__)
@app.route('/service', methods=['POST'])
def service():
data = json.loads(request.data)
text = data.get("text",None)
if text is None:
return jsonify({"message":"text not found"})
else:
return jsonify(data)
if __name__ == '__main__':
app.run(host= '0.0.0.0',debug=True)
回答 6
假设您发布了有效的JSON，
@app.route('/api/add_message/<uuid>', methods=['GET', 'POST'])
def add_message(uuid):
content = request.json
print content['uuid']
# Return data as JSON
return jsonify(content)
Assuming that you have posted valid JSON,
@app.route('/api/add_message/<uuid>', methods=['GET', 'POST'])
def add_message(uuid):
content = request.json
print content['uuid']
# Return data as JSON
return jsonify(content)
回答 7
尝试使用力参数…
request.get_json(force = True)
Try to use force parameter…
request.get_json(force = True)
