Python3解析JSON获取指定值报错：TypeError问题排查

Hey there! Let's break down why you're hitting this error and get your code working to grab that "login" value.

What's Causing the Error? #

That TypeError is spelling out the issue clearly: you're trying to use a string (like a dictionary key) to index a list, but lists only accept integers or slices for accessing their elements. This means somewhere in your parsed JSON data, a section you assumed was a dictionary is actually a list—or you're trying to pull a key directly from a list without first iterating through its items.

Example Scenario #

Chances are your JSON structure looks something like this (super common with event-style data, like GitHub API responses):

[
  {
    "type": "CreateEvent",
    "actor": {
      "login": "michael"
    }
  },
  {
    "type": "PushEvent",
    "actor": {
      "login": "jane"
    }
  }
]

If you tried code like data["type"] here, it would throw the error immediately—because data is a list, not a dictionary.

The Fix #

You need to iterate through the list first, check each dictionary entry for the "CreateEvent" type, then pull the nested "login" value. Here's a working example:

import json

# Replace this with your actual JSON source (file, API response, etc.)
json_raw = '''
[
  {
    "type": "CreateEvent",
    "actor": {
      "login": "michael"
    }
  },
  {
    "type": "PushEvent",
    "actor": {
      "login": "jane"
    }
  }
]
'''

# Parse the JSON into a Python object
parsed_data = json.loads(json_raw)

# Loop through each event in the list
for event in parsed_data:
    # Check if this is the event type we want
    if event.get("type") == "CreateEvent":
        # Grab the login value from the nested actor dictionary
        target_login = event["actor"]["login"]
        print(f"Found target login: {target_login}")  # Outputs: michael

Pro Tips #

• If you're unsure about your JSON structure, print it formatted to visualize layers clearly:

  print(json.dumps(parsed_data, indent=2))
  

• If there are nested lists in your data, make sure to index them with integers first before accessing dictionary keys (e.g., event["some_nested_list"][0]["login"]).

内容的提问来源于stack exchange，提问作者j doe