在python中用另一个较小的JSON更新一个JSON

Question

Let's say I have a very large JSON of a potentially complex structure, and I occasionally receive "update" JSON. So, I want to update only the selected keys regardless of the nested structures:

{
  "main": {
    "k1": 1000000,
    "k2": true,
    "k3": "tam",
    "k4": "gs://gcp-public-data--broad-references/hg38/v0/Homo_sapiens_assembly38.dbsnp138.vcf.idx",
    "k5": {
      "k5_1": "val5_1",
      "k5_2": "val5_2"
    }
  }
}

If I got an instruction to change just k5_1 I would get JSON:

{"main": {"k5": {"k5_2": "changed"}}}

And I want to get:

{
  "main": {
    "k1": 1000000,
    "k2": true,
    "k3": "tam",
    "k4": "gs://gcp-public-data--broad-references/hg38/v0/Homo_sapiens_assembly38.dbsnp138.vcf.idx",
    "k5": {
      "k5_1": "val5_1",
      "k5_2": "changed"
    }
  }
}

Is there a smart way to do it? Thanks!

Answer 1

Importing json gives you access to read and parse json files. Then, json.loads returns the json as a dictionary. Then you set the keys variable then json.dumps changes the dictionary to json then write it into the file.

import json as j
with open(filename,'r') as f:
   filedat = j.load( f.read())

filedat['main']['k5']['k5_2'] = 'changed'
with open(filename,'w') as f:
    f.write(j.dumps(filedat))

Answer 2

A recursive solution could be a function to merge them at dict level:

def update_dict(dict1, dict2):
    for k in dict2.keys():
        if k in dict1:
            v1 = dict1[k]
            v2 = dict2[k]
            if isinstance(v1, dict) and isinstance(v2, dict):
                update_dict(v1, v2)
            else:
                dict1[k] = v2

import json
with open(filename1,'r') as f1:
   d1 = json.load( f1.read())
with open(filename2,'r') as f2:
   d2 = json.load( f2.read())

update_dict(d1, d2)
with open(filename1,'w') as f1:
   json.dump(d1,f1)