Python add new element to existing JSON File

Question

I'm trying to append some data into a JSON file inside python. It should add the CVE-ID into my customer JSON file.

I wasn't able to solve this by myself. If I print my dict after appending it shows the expected result. But it seems, that the file will not be written after the append. I have also tried to use json.dump() after the "appending-line" - but also without success.

At the moment my code looks like this:

with open("test.json", "r+") as customerdata:
    customers_json = json.load(customerdata)

# some other code here...

if cve["cve"]["CVE_data_meta"]["ID"] not in customer["customer"]["already-sent-cve"]:
                customers_json["customers"][0]["customer"]["already-sent-cve"].append(cve["cve"]["CVE_data_meta"]["ID"])

My JSON file looks like this:

    {
        "customers":[
            {
                "customer":{
                    "id":"1",
                    "company-name":"test GmbH",
                    "alert-email":"[email protected]",
                    "using":[
                        "xxx",
                        "xyz"
                    ],
                    "already-sent-cve":[
                        "CVE-2013-3738"
                        # here new CVE
                    ]
                }
            },
        {
            "customer":{
                "id":"2",
                  ...
          }
    ]
}

FYI: There is another JSON file with the CVE's from which file I'm collecting the data.

Any suggestions how to solve this?

Regards.

EDIT:

Was able to solve this:

with open("test.json", "w") as customerdata:
    customers_json["customers"][0]["customer"]["already-sent-cve"].append(cve["cve"]["CVE_data_meta"]["ID"])
    json.dump(customers_json, customerdata, indent=2)

Your edit should be posted as an answer -- not as an update to the question — Alan Kavanagh
– Alan Kavanagh, Commented Feb 27, 2020 at 10:19

l'L'l · Accepted Answer · 2020-02-27 08:25:00Z

1

You need to write the data back to the file:

with open('test.json', 'w') as customerdata:
    json.dump(customers_json, customerdata)

answered Feb 27, 2020 at 8:25

l'L'l

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3 Comments

L.Writer Over a year ago

So but I need still the append operation? I'm not sure how I can only write back the new element or is it only possible to wirte back a complete JSON file (and not just add the needed element)?

Anurag Over a year ago

you need to write back the complete JSON file

L.Writer Over a year ago

Ahh, got it. This was my mistake. I thought I'm able to write back only a specific value. Now it seems to be working. Thanks.

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