Delete from JSON nested dictionary in list value by iteration-CodePudding

I have JSON file 'json_HW.json' in which I have this format JSON:

{
  "news": [
    {
      "content": "Prices on gasoline have soared on 40%",
      "city": "Minsk",
      "news_date_and_time": "21/03/2022"
    },
    {
      "content": "European shares fall on weak earnings",
      "city": "Minsk",
      "news_date_and_time": "19/03/2022"
    }
  ],
  "ad": [
    {
      "content": "Rent a flat in the center of Brest for a month",
      "city": "Brest",
      "days": 15,
      "ad_start_date": "15/03/2022"
    },
    {
      "content": "Sell a bookshelf",
      "city": "Mogilev",
      "days": 7,
      "ad_start_date": "20/03/2022"
    }
  ],
  "coupon": [
    {
      "content": "BIG sales up to 50%!",
      "city": "Grodno",
      "days": 5,
      "shop": "Marko",
      "coupon_start_date": "17/03/2022"
    }
  ]
}

I need to delete field_name and field_value with their keys when I reach them until the whole information in the file is deleted. When there is no information in the file, I need to delete the file itself

The code I have

data = json.load(open('json_HW.json'))  

for category, posts in data.items():
    for post in posts:
        for field_name, field_value in post.items():
            del field_name, field_value
            print(data)

But the variable data doesn't change when I delete and delete doesn't work. If it worked I could rewrite my JSON

CodePudding user response：

You are deleting the key and the value, after extracting them from the dictionary, that doesn't affect the dictionary. What you should do is delete the dictionary entry:

import json

data = json.load(open('json_HW.json'))  

for category, posts in data.items():
    for post in posts:
        for field_name in list(post.keys()):
            del post[field_name]


print(data)

which gives:

{'news': [{}, {}], 'ad': [{}, {}], 'coupon': [{}]}

Note that the list() is necessary, post.keys() is a generator and you cannot change the dict while you are iterating over its keys (or items or values).

I assumed test_data should have been data.

CodePudding user response：

if you want to delete key-value from dictionary, you can use del post[key]. but i don't think it works for iteration, cause dictionary size keeps changing. https://www.geeksforgeeks.org/python-ways-to-remove-a-key-from-dictionary/