How to convert nested JSON to CSV using only jq - json

Question

I've following json,
{
"A": {
"C": {
"D": "T1",
"E": 1
},
"F": {
"D": "T2",
"E": 2
}
},
"B": {
"C": {
"D": "T3",
"E": 3
}
}
}
I want to convert it into csv as follows,
A,C,T1,1
A,F,T2,2
B,C,T3,3
Description of output: The parents keys will be printed until, I've reached the leaf child. Once I reached leaf child, print its value.
I've tried following and couldn't succeed,
cat my.json | jq -r '(map(keys) | add | unique) as $cols | map(. as $row | $cols | map($row[.])) as $rows | $rows[] | #csv'
and it throwing me an error.
I can't hardcode the parent keys, as the actual json has too many records. But the structure of the json is similar. What am I missing?

Answer 1

Some of the requirements are unclear, but the following solves one interpretation of the problem:
paths as $path
| {path: $path, value: getpath($path)}
| select(.value|type == "object" )
| select( [.value[]][0] | type != "object")
| .path + ([.value[]])
| #csv
(This program could be optimized but the presentation here is intended to make the separate steps clear.)
Invocation:
jq -r -f leaves-to-csv.jq input.json
Output:
"A","C","T1",1
"A","F","T2",2
"B","C","T3",3
Unquoted strings
To avoid the quotation marks around strings, you could replace the last component of the pipeline above with:
join(",")

Answer 2

Here is a solution using tostream and group_by
[
tostream
| select(length == 2) # e.g. [["A","C","D"],"T1"]
| .[0][:-1] + [.[1]] # ["A","C","T1"]
]
| group_by(.[:-1]) # [[["A","C","T1"],["A","C",1]],...
| .[] # [["A","C","T1"],["A","C",1]]
| .[0][0:2] + map(.[-1]|tostring) # ["A","C","T1","1"]
| join(",") # "A,C,T1,1"