Python JSON append if value doesnät exist

I've got a json file with 30-ish, blocks of "dicts" where every block has and ID, like this:

{
      "ID": "23926695",
      "webpage_url": "https://.com",
      "logo_url": null,
      "headline": "aewafs",
      "application_deadline": "2020-03-31T23:59:59",
}

Since my script pulls information in the same way from an API more than once, I would like to append new "blocks" to the json file only if the ID doesn't already exist in the JSON file.

I've got something like this so far:

import os

check_empty = os.stat('pbdb.json').st_size
if check_empty == 0:
    with open('pbdb.json', 'w') as f:
        f.write('[\n]')    # Writes '[' then linebreaks with '\n' and writes ']'
output = json.load(open("pbdb.json"))

for i in jobs:
    output.append({
        'ID': job_id, 
        'Title': jobtitle, 
        'Employer' : company, 
        'Employment type' : emptype, 
        'Fulltime' : tid, 
        'Deadline' : deadline, 
        'Link' : webpage
    })

with open('pbdb.json', 'w') as job_data_file:
    json.dump(output, job_data_file)

but I would like to only do the "output.append" part if the ID doesn't exist in the Json file.