Write in json file with Python

Question

For a project I need to write in a json file with python but all I have already seen (json.dump) don't match with what I want to do...

I have a structure and I just want to add something inside. I want to add a service with a input for example :

{
"Serial_011": "011",
"Servers_011":
    [
        {
            "hostname": "srv-a.11",
            "ipv4_address": "0.0.0.0",
            "services":
                [
                    {
                        "uri": "http://www.google.fr/1",
                        "expected_code": 200
                    },
                    {
                        "uri": "http://www.google.fr/2",
                        "expected_code": 200
                    }
                ]
        },
        {
            "hostname": "nsc-srv-b.11",
            "ipv4_address": "0.0.0.0",
            "services":
                [
                    {
                        "uri": "http://www.google.fr/3",
                        "expected_code": 200
                    },
                    {
                        "uri": "http://www.google.fr/4",
                        "expected_code": 200
                    }
                ]
        }
    ]
}

Thanks in advance

Read the JSON into an object, add your info to that object and serialize it again (with prettyprinting if needed). — MKesper, Aug 02 '16 at 09:14
If you don't have a special file format then the usual way of adding something not-just-at-the-end is loading it, modifying it and then writing back the whole thing. (On large files you try to use a streaming approach) — janbrohl, Aug 02 '16 at 09:18
I have already open the json with 'with open...' but ithe problem is for the writing — msommer, Aug 02 '16 at 09:41
@M_S I've posted an answer for this issue. Can you try that? You can definitely use the `with` clause with my answer. Thank you. — Sreejith Menon, Aug 02 '16 at 10:04

Sreejith Menon · Accepted Answer · 2016-08-02T10:11:42.190

2

I keep in mind 4 methods while I work with JSON objects in python.

json.dumps(<a python dict object>) - gives a string representation of json formed out of the python dict object
json.dump( <a python dict object>,<file obj>) - writes a json file in file object
json.loads(<a string>) - reads a json object from a string
json.load(<a json file>) - reads a json object from the file.

The next important thing to keep in mind is that json's and dict in python are equivalent.

So let us say, the file contents reside inside a file addThis.json. You have a already existing json object inside the file existing.json.

The below code should be able to do the job

import json

existing = json.load(open("/tmp/existing.json","r"))
addThis = json.load(open("/tmp/addThis.json","r"))

for key in addThis.keys():
     existing[key] = addThis[key]

json.dump(exist,open("/tmp/combined.json","w"),indent=4)

Edit: Assuming the contents of the addThis is not in a file but is to be read from the console.

import json

existing = json.load(open("/tmp/existing.json","r"))

addThis = input()
# paste your json here.
# addThis is now simply a string of the json content of what you to add

addThis = json.loads(addThis) #converting a string to a json object.
# keep in mind we are using loads and not load

for key in addThis.keys():
     existing[key] = addThis[key]

json.dump(exist,open("/tmp/combined.json","w"),indent=4)

edited Aug 02 '16 at 10:11

answered Aug 02 '16 at 09:49

Sreejith Menon

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So in existing.json I will put the current json, in addThis.json I write what I want to add with an input() and the result will be conbined.json ? – msommer Aug 02 '16 at 10:04
To clarify, the contents (the one that is to be added) is to be read from input()? – Sreejith Menon Aug 02 '16 at 10:06
@M_S I've added the code for reading the new json contents from `input()` as well. Please up vote and confirm the answer if this works. Thank you. – Sreejith Menon Aug 02 '16 at 10:12
It's turn in loop... What is exist in json.dump ? – msommer Aug 02 '16 at 10:38
Could you be a little more clearer? – Sreejith Menon Aug 02 '16 at 11:11
It's doing nothing and rest like that like in an infinite loop – msommer Aug 02 '16 at 11:16
Can you provide your work! I've tested this before I posted it. So for the requirements I have explained it works without any issues. Please be sure of what you want. – Sreejith Menon Aug 02 '16 at 11:49

Write in json file with Python

1 Answers1