Python 3.7如何实现文本/JSON文件键值的搜索更新与新增？

Great call switching to JSON for this task—working with key-value pairs becomes way more straightforward compared to hacking plain text files. Your current code only handles line-by-line replacement, but JSON’s native dictionary structure in Python makes updating/adding keys trivial. Here’s how to implement your exact requirement:

Step-by-Step Implementation #

First, let’s outline the core logic:

• Load existing JSON data (initialize an empty dictionary if the file doesn’t exist)
• Parse your input string (e.g., C3:21,40 or C5:32,11) into a key and value
• Update the dictionary: overwrite the value if the key exists, add a new key-value pair if it doesn’t
• Save the updated dictionary back to the JSON file

Full Code Example #

import json
import os

def parse_input(input_str):
    """Parse input strings like 'C3:21,40' into a key and value"""
    key, value = input_str.split(':', 1)
    return key.strip(), value.strip()

def update_key_value(file_path, input_str):
    # Load existing data or initialize empty dict
    if os.path.exists(file_path):
        with open(file_path, 'r') as f:
            try:
                data = json.load(f)
            except json.JSONDecodeError:
                # Handle corrupted JSON by resetting to empty dict
                data = {}
    else:
        data = {}
    
    # Parse and update data
    key, value = parse_input(input_str)
    data[key] = value
    
    # Write updated data back to file (formatted for readability)
    with open(file_path, 'w') as f:
        json.dump(data, f, indent=4)

# Test the function
update_key_value('data.json', 'C3:21,40')  # Updates existing C3 entry
update_key_value('data.json', 'C5:32,11')  # Adds new C5 entry

Optional: Store Values as Numeric Lists #

If you want to work with the numeric values (instead of raw strings), modify the parse_input function to convert the value into a list of integers:

def parse_input(input_str):
    key, value_part = input_str.split(':', 1)
    value = [int(num.strip()) for num in value_part.split(',')]
    return key.strip(), value

This will store entries like {"C3": [21, 40]} in the JSON file, making it easier to perform calculations later.

Why This Is Better Than Your Original Text File Approach #

Your current fileinput code works for simple line replacement, but it has limitations:

• You’d have to manually search each line for the target key, which is error-prone if lines are formatted inconsistently
• Adding new keys would require appending to the file, which adds extra logic
• JSON handles all the serialization/deserialization automatically, so you don’t have to worry about formatting edge cases

内容的提问来源于stack exchange，提问作者Wrongway Feldman