Python与JSON技术问题：无法通过索引访问维基百科API返回的动态键字典数据

The Problem #

You’re trying to fetch a Wikipedia article’s summary via their API, but hitting a KeyError: 0 when trying to access the extract field. Here’s your original code:

import json
import requests
article_name = "BT Centre"
article_api_url = "https://en.wikipedia.org/w/api.php?format=json&action=query&prop=extracts&exintro=&explaintext=&titles={}".format(article_name)
called_data = requests.get(article_api_url)
formatted_data = called_data.json()
print(formatted_data)
pages = formatted_data["query"]["pages"]
print(pages)
first_page = pages[0]["extract"]
print(first_page)

When you run this, the API returns JSON where the pages object is a dictionary (not a list) with a dynamic string key (the page ID, like 18107207):

{
 'batchcomplete': '',
 'query':{
 'pages':{
 '18107207':{
 'pageid': 18107207,
 'ns': 0,
 'title':'BT Centre',
 'extract': "The BT Centre is the global headquarters and registered office of BT Group..."
 }
 }
 }

The error happens because you’re treating pages like a list and trying to index it with [0], but it’s actually a dict with numeric string keys. Hardcoding the page ID (like pages["18107207"]) also won’t work since it changes per article.

Solutions #

1. Iterate to find the numeric page ID (Ann Zen’s approach)

Loop through the keys of the pages dict and check for a numeric key (which is always the page ID in this response):

for key in pages:
    if key.isdigit():
        print(pages[key]["extract"])

2. Directly get the first page value (simpler for single article queries)

Since you’re querying a single article, the pages dict will only have one entry. You can grab its value directly without looping:

# Get the first (and only) page object from the pages dict
page = next(iter(pages.values()))
print(page["extract"])

This works because iter(pages.values()) creates an iterator over the dict’s values, and next() grabs the first one—perfect when you know there’s only one article result.

内容的提问来源于stack exchange，提问作者GameDesert