How to remove empty { } from JSON file using python

Question

I have done my research but I couldn't find any answers that worked.

I have the following JSON file:

{
    "Cars": [{
            "Manufacturer": "Audi",
            "model": "R8",
            "price": 50000,
            "a": {
                "n": "1",
                "street": "ABC Street",
                "city": "London",
                "postcode": "TW1 1AA"
            }
        },
        {
            "Manufacturer": "Ford",
            "model": "Fiesta",
            "price": 10000,
            "a": {
                "n": 2,
                "street": "DEF street",
                "town": "London",
                "PostCode": "TW2 2AB"
            }
        },
        {
            "Manufacturer": "VW",
            "model": "Polo",
            "price": 5000,
            "a": {
                "n": "3",
                "Street": "GHI Street",
                "town": "London",
                "postcode": "TW3 3CD"
            }
        }

    ]
}

In my python file, to remove the JSON elements, I am using the following:

deletecar = int(input("Enter price of car to delete: "))
for item in data["Cars"]:
   if deletecar == item["price"]:
      item.pop("Manufacturer")
      item.pop("model")
      item.pop("price")
      item.pop("a")

      with open("testjson.json", 'w') as f:
          json.dump(data, f)

When I run this, if I delete the first car in the JSON file, I find this:

{"Cars": [{}, {"Manufacturer": "Ford", ...

If I now run my program again, but I try to search for cars, the program won't work due to these empty braces.

So how can I remove them using Python?

Thanks in advance.

Removing the individual keys is wrong; you should remove the entire sub-dict if its price matches. But in addition, you should not modify the dict you are iterating over. Collect the items you want to remove, then remove them outside the loop. — tripleee
– tripleee, Commented Jan 7, 2020 at 12:20
You want to filter the list of cars and remove any cars where the price matches a certain value…!? — deceze
– deceze ♦, Commented Jan 7, 2020 at 12:21
@deceze - Yes, that is my aim. I have asked the 'user' to remove a car by entering a price, and my program does that based on their input. This part works fine, its just after the deletion that is the issue. — theoneandonly
– theoneandonly, Commented Jan 7, 2020 at 12:23
"This part works fine, its just after the deletion that is the issue. " meaning it doesn't "work fine", because rather than removing the entry itself you're just removing the contents of the entry. — Masklinn
– Masklinn, Commented Jan 7, 2020 at 12:24
@Masklinn - So you are saying I need to use del instead of .pop()? — theoneandonly
– theoneandonly, Commented Jan 7, 2020 at 12:30

Masklinn · Accepted Answer · 2020-01-07 12:24:00Z

1

You need to remove the item itself, which means you need two steps:

find the index at which the item you want to remove is
remove the item from the list (with del)

And you don't need to "empty" the dict as that's not what you're looking for.

Alternatively, you could create a brand new list without the offending item using a list comprehension or a filter call e.g.

deletecar = int(input("Enter price of car to delete: "))
data['Cars'] = [
    item for item in data['Cars']
    if item['price'] != deletecar
]

with open("testjson.json", 'w') as f:
      json.dump(data, f)

(note: this "removes" all items which match, rather than just the first as your code does).

Also you probably want to save after you're done processing, not during processing.

answered Jan 7, 2020 at 12:24

Masklinn

43.8k4 gold badges58 silver badges78 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

chitown88 · Accepted Answer · 2020-01-07 12:28:39Z

0

Since it's a list, you can find the index values in your list that match your price input. Then remove those elements from values in the 'Cars' list

deletecar = int(input("Enter price of car to delete: "))

# Get the index values of where the item is located
index_to_delete = []
for item in data["Cars"]:
   if deletecar == item["price"]:
      index_to_delete.append(data["Cars"].index(item))

# Since the index values will change as you delete them,
# you will have to remove them in reverse order (in case there's more than 1 
# item being removed

for i in reversed(index_to_delete):
    del data["Cars"][i]      

# write to file      
with open("testjson.json", 'w') as f:
    json.dump(data, f)

answered Jan 7, 2020 at 12:28

chitown88

29.1k6 gold badges34 silver badges67 bronze badges

Collectives™ on Stack Overflow

How to remove empty { } from JSON file using python

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related