如何从json提取数据

Question

我想从下面提到的json对象中提取特定值。但是它给了一些错误

   >>> print json
{
 "response_code": 1,
 "verbose_msg": "Scan finished, scan information embedded in this object",

 "resource": "99017f6eebbac24f351415dd410d522d",
 "scan_id": "52d3df0ed60c46f336c131bf2ca454f73bafdc4b04dfa2aea80746f5ba9e6d1c-1273894724",
 "md5": "99017f6eebbac24f351415dd410d522d",
 "sha1": "4d1740485713a2ab3a4f5822a01f645fe8387f92",
 "sha256": "52d3df0ed60c46f336c131bf2ca454f73bafdc4b04dfa2aea80746f5ba9e6d1c",

 "scan_date": "2010-05-15 03:38:44",

 "positives": 40,
 "total": 40,

 "scans": {"nProtect": {"detected": true, "version": "2010-05-14.01", "result": "Trojan.Generic.3611249", "update": "20100514"},
           "CAT-QuickHeal": {"detected": true, "version": "10.00", "result": "Trojan.VB.acgy", "update": "20100514"},
           "McAfee": {"detected": true, "version": "5.400.0.1158", "result": "Generic.dx!rkx", "update": "20100515"},
           "TheHacker": {"detected": true, "version": "6.5.2.0.280", "result": "Trojan/VB.gen", "update": "20100514"},
           "VirusBuster": {"detected": true, "version": "5.0.27.0", "result": "Trojan.VB.JFDE", "update": "20100514"},
           "NOD32": {"detected": true, "version": "5115", "result": "a variant of Win32/Qhost.NTY", "update": "20100514"},
           "F-Prot": {"detected": false, "version": "4.5.1.85", "result": null, "update": "20100514"},
           "Symantec": {"detected": true, "version": "20101.1.0.89", "result": 
 "permalink": "https://www.virustotal.com/file/52d3df0ed60c46f336c131bf2ca454f73bafdc4b04dfa2aea80746f5ba9e6d1c/analysis/1273894724/"

等等.... }

为了实现以上目标，我编写了以下代码：

            data = json.loads(json_post)
            response_dict = simplejson.loads(json_post)
            logging.info(response_dict)
            if response_dict['response_code'] == 0:
                self.response.out.write("11")


            elif response_dict['response_code'] == -2:
                self.response.out.write("API Request Rate Limit Exceeded<br/>")
            elif response_dict['response_code'] == -1:
                self.response.out.write("API Key provided is wrong<br/>")
            elif response_dict['response_code'] == 1:
                link.req_timestamp = response_dict['scans'][0]

                Fire_fox=response_dict.get("scans")[1].get("Firefox")
                if Fire_fox:
                    link.firefox = data['scans'][1]['Firefox']

                Trend_Micro=response_dict.get("scans")[1].get("TrendMicro")
                if Trend_Micro:
                    link.trendmicro = data['scans'][1]['TrendMicro']

                Phishtank=response_dict.get("scans")[1].get("Phishtank")
                if Phishtank:
                    link.phishtank = data['scans'][1]['Phishtank']

错误是KeyError：'scans'.. plz告诉我我要去哪里错了

Answer 1

您应该检查http://docs.python.org/2/tutorial/datastructures.html

>>> response_dict.has_key('scans')
True
>>> response_dict["scans"].has_key(1)
False
>>> response_dict["scans"].get(1, "Not Found")
'Not Found'
>>> response_dict["scans"][1]

Traceback (most recent call last):
  File "<pyshell#3>", line 1, in <module>
    response_dict["scans"][1]
KeyError: 1

我不知道您想从代码中做什么，但是这段代码可以帮助您：

for key in response_dict["scans"].keys():
    setattr(link, key.lower().replace("-","_"), response_dict["scans"][key])

要么：

for key in ["Firefox", "TrendMicro", "Phishtank", "McAfee"]:
    if scans.has_key(key):
        setattr(link, key.lower(), response_dict["scans"][key])

字典非常有用：

responses = {0:"11",
             -1:"API Key provided is wrong",
             -2:"API Request Rate Limit Exceeded<br/>"}

code = response_dict['response_code']
if responses.has_key(code):
    self.response.out.write(responses[code])

Answer 2

考虑到您使用的json结构的复杂性，我将更倾向于使用一个库，该库使从该结构中提取数据更加容易。

例如查看https://pypi.python.org/pypi/jsonpath-rw/1.1.2 。

同样，您似乎经常在尝试使用键访问列表等时犯同样的错误（在您发布的另外两个SO问题中）。...您需要掌握基本的编程技能，并了解数据是什么您正在使用的结构。