为何Reddit Bot无法存储评论ID至JSON文件，重启后重复回复？

问题根源 #

1. JSON写入方式错误：使用"a"（追加）模式写入JSON文件，每次回复后将整个answered_comments字典追加到文件末尾，导致JSON结构混乱，程序重启时无法正确解析已存储的评论ID，进而重复回复。
2. JSON解析错误处理缺失：当comment_id.json格式损坏时，仅定义了空字典data，未重置answered_comments为空，可能引发后续逻辑异常。
3. 冗余数据存储：answered_comments[comment.id] = {"ID": comment.id}属于冗余存储，字典的key已经是评论ID，无需重复存储值。

修改后的完整代码 #

import time
import json
import os
import requests
import praw

# Reddit
CLIENT_ID = 'xxx'
CLIENT_SECRET = 'xxx'
USERNAME = 'xxx'
PASSWORD = 'xxx'
USER_AGENT = 'xxx'

# NASA
NASA_API = 'xxxxxxxxx'
NASA_HTTP = 'https://api.nasa.gov/planetary/apod'

# 初始化Reddit客户端
reddit = praw.Reddit(client_id=CLIENT_ID,
                     client_secret=CLIENT_SECRET,
                     username=USERNAME,
                     password=PASSWORD,
                     user_agent=USER_AGENT)

# 指定操作的子版块
subreddit = reddit.subreddit('xxx')

# 记录最新评论时间
last_comment_time = time.time()

answered_comments = {}

# 加载已回复的评论ID
try:
    with open("comment_id.json", "r") as data_file:
        answered_comments = json.load(data_file)
except FileNotFoundError:
    # 文件不存在时创建空文件
    with open("comment_id.json", "w") as data_file:
        json.dump(answered_comments, data_file, indent=4)
except json.decoder.JSONDecodeError:
    # 格式错误时重置为空字典并重新创建文件
    answered_comments = {}
    with open("comment_id.json", "w") as data_file:
        json.dump(answered_comments, data_file, indent=4)

# 封装保存已回复ID的函数，避免重复代码
def save_answered_comments():
    with open("comment_id.json", "w") as data_file:
        json.dump(answered_comments, data_file, indent=4)

while True:
    # 获取最新评论
    new_comments = subreddit.comments(params={"after": last_comment_time})

    for comment in new_comments:
        # 更新最新评论时间
        if comment.created_utc > last_comment_time:
            last_comment_time = comment.created_utc

        # 处理/nasa指令
        if '/nasa' in comment.body.lower():
            if comment.id not in answered_comments:
                # 请求NASA API参数
                parameters = {
                    "api_key": NASA_API,
                    "hd": True
                }
                response = requests.get(NASA_HTTP, params=parameters)
                response.raise_for_status()
                data = response.json()
                image_url = data["hdurl"]

                # 回复评论
                comment.reply('NASA Image of the Day: ' + image_url)

                # 记录已回复的评论ID
                answered_comments[comment.id] = True
                # 保存到文件
                save_answered_comments()

        # 处理/indir指令
        if '/indir' in comment.body.lower():
            if comment.id not in answered_comments:
                post = comment.parent()
                if post.media:
                    video_url = post.media['reddit_video']['fallback_url']
                    comment.reply('Video URL: ' + video_url)
                else:
                    comment.reply('Bu indirilebilecek bir video değil.')
                
                # 记录已回复的评论ID
                answered_comments[comment.id] = True
                # 保存到文件
                save_answered_comments()

    # 每10分钟刷新一次
    time.sleep(10 * 60)

关键修改说明 #

• 修改JSON写入模式：将追加模式"a"改为覆盖模式"w"，每次回复后完整写入answered_comments字典，保证JSON格式始终正确。
• 完善错误处理：当JSON解析失败时，重置answered_comments为空字典并重新创建文件，避免后续逻辑异常。
• 封装保存函数：将重复的JSON写入逻辑封装成save_answered_comments函数，减少代码冗余。
• 简化数据存储：将answered_comments的value改为True，避免冗余存储评论ID，也可以改用集合（answered_comments = set()）进一步优化空间。

内容的提问来源于stack exchange，提问作者Cihan Yalçın