在 Python 中迭代 JSON

Question

我正在尝试从以 JSON 对象形式返回数据的 API 中提取数据。我有 API 调用，它返回看起来像这样的数据（为简洁起见，此处缩短）

   "status":"OK",
   "copyright":"Copyright (c) 2017 Pro Publica Inc. All Rights Reserved.",
   "results":[
      {
         "num_results": 10,
         "offset": 0,
         "bills": [
              {
                 "bill_id": "hr2739-113",
                 "bill_type": "hr",
                 "number": "H.R.2739",
                 "bill_uri": "https://api.propublica.org/congress/v1/113/bills/hr2739.json",
                 "title": "Efficient Use of Government Spectrum Act of 2013",
                 "sponsor_title": "Rep.",
                 "sponsor_id": "M001163",
                 "sponsor_name": "Doris Matsui",
                 "sponsor_state": "CA",
                 "sponsor_party": "D",
                 "sponsor_uri": "https://api.propublica.org/congress/v1/members/M001163.json",
                 "gpo_pdf_uri": "http://www.gpo.gov/fdsys/pkg/BILLS-113hr2739ih/pdf/BILLS-113hr2739ih.pdf",
                 "congressdotgov_url": "https://www.congress.gov/bill/113th-congress/house-bill/2739",
                 "govtrack_url": "https://www.govtrack.us/congress/bills/113/hr2739",
                 "introduced_date": "2013-07-18",
                 "committees": "House Armed Services Committee",
                 "committee_codes": ["HSAS","HSIF"],
                 "subcommittee_codes": ["HSAS26","HSIF16"],
                 "primary_subject": "Science, Technology, Communications",
                 "summary_short": "Efficient Use of Government Spectrum Act of 2013 - Directs the Federal Communications Commission (FCC), within three years after enactment of the Middle Class Tax Relief and Job Creation Act of 2012, to: (1) reallocate electromagnetic spectrum between the frequencies from 1755 to 1780 megahertz (currently, such frequencies are occupied by the Department of Defense [DOD] and other federal agencies); and (2) as part of the competitive bidding auctions required by such Act, grant new initial lic...",
                 "latest_major_action_date": "2013-08-29",
                 "latest_major_action": "Referred to the Subcommittee on Intelligence, Emerging Threats & Capabilities."
              },
                           {
                 "bill_id": "hr3355-113",
                 "bill_type": "hr",
                 "number": "H.R.3355",
                 "bill_uri": "https://api.propublica.org/congress/v1/113/bills/hr3355.json",
                 "title": "Reducing Employer Burdens, Unleashing Innovation, and Labor Development Act of 2013",
                 "sponsor_title": "Rep.",
                 "sponsor_id": "G000558",
                 "sponsor_name": "Brett Guthrie",
                 "sponsor_state": "KY",
                 "sponsor_party": "R",
                 "sponsor_uri": "https://api.propublica.org/congress/v1/members/G000558.json",
                 "gpo_pdf_uri": "http://www.gpo.gov/fdsys/pkg/BILLS-113hr3355ih/pdf/BILLS-113hr3355ih.pdf",
                 "congressdotgov_url": "https://www.congress.gov/bill/113th-congress/house-bill/3355",
                 "govtrack_url": "https://www.govtrack.us/congress/bills/113/hr3355",
                 "introduced_date": "2013-10-28",
                 "committees": "House Armed Services Committee",
                 "primary_subject": "Economics and Public Finance",
                 "summary_short": "Reducing Employer Burdens, Unleashing Innovation, and Labor Development Act of 2013 - Expresses the sense of Congress that increasing the competitiveness of U.S. manufacturers will strengthen the national economy. Title I: Investing in America's Workforce - Investing in America's Workforce Act - Amends the Workforce Investment Act of 1998 to require state or local workforce investment systems to use youth activities funds allocated to a local area for programs that provide training, which may...",
                 "latest_major_action_date": "2014-01-24",
                 "latest_major_action": "Referred to the Subcommittee on Intelligence, Emerging Threats & Capabilities."
              },

使用 Python，我正在尝试遍历数据并返回所有值，如下所示：

import requests
import json

r = requests.get({url and credentials here}).text

resp = json.loads(r)


for bill in resp['results']['bills']:
    name = bill['results']['bills']['title']
    type = item['results']['bills']['bill_type']

print(name, type)

但是，每当我尝试运行它时，我都会得到 ​​p>

TypeError: list indices must be integers or slices, not str

为什么我不能将列表索引用作 str？存在大量使用 str 的示例。

Answer 1

json 中的“票据”是一个对象列表（例如 "bills" : [ - 左括号是方括号，表示一个列表）。

你必须使用整数来访问列表的元素，所以你可以说;

resp['results'][0]['bills'][0]

例如，访问第一张账单。

但是，您的代码在循环中有点混乱，bill 变量将包含每张账单的信息，因此您可以直接引用键，例如在第一个结果中循环账单

for bill in resp['results'][0]['bills']:
    name = bill['title']
    type = bill['bill_type']

    print(name, type)

变量“名称”和“类型”将仅包含循环块期间每个账单的详细信息。

你可以嵌套循环来遍历所有结果

for result in resp['results']:
  for bill in result['bills']:
      name = bill['title']
      type = bill['bill_type']

      print(name, type)

Answer 2

bill 是一个没有results 或bills 作为字符串索引的json 对象。请尝试以下操作：

for bill in resp['results']['bills']:
    name = bill['title']
    type = item['bill_type']

    print(name, type)

Answer 3

在 json 数据中，results 是一个字典列表。 所以首先迭代结果。 然后为每个结果遍历账单以检索账单的名称和类型。

for result in resp['results']:
    for bill in result['bills']:
        name = bill['title']
        type = item['bill_type']
        print(name, type)

Answer 4

同样在您的代码中，名称等于：

name = bill['results']['bills']['title'] -> resp['results']['bills']['results']['bills']['title']

Answer 5

如果您收到 JSON 响应，请找到以下两种解析方法。

方法 1：正常方式 - 这是您正在尝试的方法

import requests


resp = requests.get(url="url",auth="cred").json()

for bill in resp['results'][0]['bills']:
    bill_name = bill['title']
    bill_type = bill['bill_type']

print(bill_name, bill_type)

方法 2：访问 json 响应的更简洁方法

for bill_dict in resp.get("results", []):  # returns None if "results" field is not found
    for bill in bill_dict.get('bills', []): 
        bill_name = bill.get('title')  # None is assigned to bill_name if key 'title' is not found
        bill_type = bill.get('bill_type')  # None is assigned to bill_name if key 'title' is not found error OR you can assign default value if key is not found Ex: bill.get('bill_type', 'bill type unavailable')

print(bill_name, bill_type)

还有很多其他方法。