Python - 如何使用 json.load 遍历 JSON 数据

Question

I have the below JSON, which I parse with json.load()

{
"participants": [
    {
        "name": "Joseph Bloggs"
    },
    {
        "name": "John Doe"
    }
],
"messages": [
    {
        "sender_name": "Joseph Bloggs",
        "timestamp_ms": 1606943360034,
        "content": "Hello John",
        "type": "Generic"
    },
    {
        "sender_name": "John Doe",
        "timestamp_ms": 1606943285176,
        "content": "Hi Joe",
        "type": "Generic"
    },

I tried to iterate through the messages to search for strings inside each value.

import json 

data = json.load(f)
   
for msg in data['messages']:

    search = 'Jo'

    if search in str(msg['sender_name']) :
      print (msg['sender_name'])

This works and outputs a "Joe Bloggs" or "John Doe" string for every message object.

If I try and search for any other keys , timestamp, content, type, I get a KeyError, eg trying to search for all messages where they participants use the word "Hello".

if search in str(msg['content']) :
          print (msg['content'])

results in a key error:

in <module>
    if search in str(msg['content']) :
KeyError: 'content'

I think I am not understanding something about json.load and Python dictionaries/lists. Why is it that msg[sender_name] works but not msg[content]? Thanks

Answer 1

I just tried.get('content') and it worked...

 search = 'Thing I am searching for'

    if search in str(msg.get('content')) :
        print (msg.get('content'))

If anyone could elaborate I would appreciate it. I've found a solution, but I'd like to understand the 'why'. Thanks

Answer 2

You can avoid KeyError with the.get() method on the dictionary

if search in str(msg.get('content')):
    print(str(msg.get('sender_name')))