Update JSON file properties with Python

Question

I'm trying to update test.json file with a Python script. I only need to change the property of "plan2"->"2"->"rooms" to 3. Could you please help me with this? Thank you very much

test.json

{
"plan1" : [{
      "1": {
      "rooms":"2",
      "bathrooms":"1",
      "kitchens":"1"
      },

      "2": {
      "rooms":"1",
      "bathrooms":"1",
      "kitchens":"1"
      }
}],
"plan2":[{
      "1": {
      "rooms":"3",
      "bathrooms":"1",
      "kitchens":"1"
      },

      "2": {
      "rooms":"1",
      "bathrooms":"1",
      "kitchens":"1"
      }
}]
}

test.py

import json

with open("test.json", "r+") as jsonFile:
    data = json.load(jsonFile)

    # need to change the "plan2"->"apartments"->"2"->"rooms" to 3 

    jsonFile.seek(0)  # rewind
    json.dump(data, jsonFile)
    jsonFile.truncate()

Yes,it works! Thanks so much, But in my actual test.json there is another `"id" : plan2. I modified the question. — root
– root, Commented Feb 27, 2019 at 13:50

bumblebee · Accepted Answer · 2019-02-27 14:10:16Z

1

import json

with open("test.json", "r+") as jsonFile:
    data = json.load(jsonFile)

    # The change
    d['plan2'][0]['1']['rooms'] = 3

    jsonFile.seek(0)
    json.dump(data, jsonFile)
    jsonFile.truncate()

edited Feb 27, 2019 at 14:10

answered Feb 27, 2019 at 13:41

bumblebee

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8 Comments

Sumit S Chawla Over a year ago

It should be data['apartments'][0]['2']['rooms'] = 3 as mentioned: "apartments"->"2"->"rooms"

root Over a year ago

Sorry I forgot to add a part of the json file. Could you please modify the answer? Thanks so much

bumblebee Over a year ago

@brabbit640 Can you please update on which plan you want to change the rooms value.

bumblebee Over a year ago

@brabbit640 I think there is a problem with the json data. With your json there is duplicate id key. Maintain it as a json array.

bumblebee Over a year ago

@brabbit640 Updated the answer.

|

chepner · Accepted Answer · 2019-02-27 13:45:06Z

1

You are modifying an in-memory data structure, not the file itself. To be completely safe, do this in four steps:

Read the file into memory
Make the changes to your data structure
Write the changes back to a new file
After the write successfully completes, replace the old file with the new.

Putting it together,

import json
import tempfile

with open("test.json") as f:
    data = json.loa(f)

data['apartments'][0]['2'][rooms] = 3

with tempfile.NamedTemporaryFile(delete=False) as f:
    json.dump(data, f)
    os.rename(f.name, "test.json")

This assumes that your temporary directory is on the same file system as your JSON file, so that the rename operation is atomic. If that is not the case, use the dir argument to NamedTempfile to specify a directory that is on the same file system.

answered Feb 27, 2019 at 13:45

chepner

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1 Comment

root Over a year ago

Really sorry I missed a part in my json file :( Could you please modify the answer. Thanks so much

oliv · Accepted Answer · 2019-02-27 14:19:16Z

0

Not a python answer, but if you have jq available on your system, you can use this:

jq '.plan2[]."2".rooms="3"' test.json

Demo on jqplay

answered Feb 27, 2019 at 14:19

oliv

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