Converting large nested JSON to CSV

Question

I am fairly new to Python and have several nested JSON files I need to convert to CSV's.

The structure of these is the following:

{'Z': {'@SchemaVersion': 9,
  'FD': [{'FDRecord': [{'NewCase': {'@TdrRecVer': 5,
   'CaseLabel': '',
   'StdHdr': {'DevDateTime': '2000-05-02T10:43:18',
    'ElapsedTime': 0,
    'GUID': '5815D34615C15690936B822714009468',
    'MsecTime': 5012,
    'RecId': 4},
   'UniqueCaseId': '5389F346136315497325122714009468'}},
 {'NewCase': {'@TdrRecVer': 5,
   'CaseLabel': '',
   'StdHdr': {'DevDateTime': '2000-05-02T10:43:18',
    'ElapsedTime': 0,
    'GUID': '5819D346166610458312622714009468',
    'MsecTime': 9459,
    'RecId': 4},
   'UniqueCaseId': '5819F346148627009653284714009468'}},
 {'AnnotationEvt': {'@EvtName': 'New',
   '@TdrRecVer': 1,
   'DevEvtCode': 13,
   'Payload': '0 0 0 0',
   'StdHdr': {'DevDateTime': '2000-05-02T10:43:18',
    'ElapsedTime': 0,
    'GUID': '5899D34616BC1000938B824538219968',
    'MsecTime': 7853,
    'RecId': 8},
   'TreatmentSummary': 1,
   'XidCode': '0000000B'}},
 {'TrendRpt': {'@TdrRecVer': 9,
   'CntId': 0,
   'DevEvtCode': 30,
   'StdHdr': {'DevDateTime': '2000-05-02T10:43:18',
    'ElapsedTime': 0,
    'GUID': '5819C34616781004852225698409468',
    'MsecTime': 4052,
    'RecId': 12}, ...

My problem is, most examples online show how to read in a very small json and write it out to a csv by explicitly stating the keys or field names when creating a csv. My files are far too large to do this, some of them being over 40MB.

I tried following another person's example (below) from online, but did not succeed:

import json
import csv

with open('path-where-json-located') as file:
    data_parse = json.load(file)

data = data_parse['Z']

data_writer = open('path-for-csv', 'w')

csvwriter = csv.writer(data_writer)

count=0
for i in data:
    if count == 0:
        header = i.keys()
        csvwriter.writerow(header)
        count+=1
    csvwriter.writerow(i.values())

data_writer.close()

When I run this, I get the following error:

AttributeError: 'str' object has no attribute 'keys'

I understand that for some reason it is treating the key I want to pull as a string object, but I do not know how to get around this and correctly parse this into a csv.