BigQuery JSON element extraction - json

Question

I have a table in BigQuery with a JSON column, see below.
doc_id
data
222
{...}
333
{...}
The data JSON column looks like the IDs are set as headers.
{
"1675223776617": {
"author": "aaa",
"new": "2023-02-01",
"old": null,
"property": "asd",
"sender": "wew"
},
"1675223776618": {
"author": "aaa",
"new": true,
"old": null,
"property": "asd",
"sender": "ewew"
},
"1675223776619": {
"author": "bbb",
"new": "ySk2btk7",
"old": null,
"property": "qwe",
"sender": "yyy"
}
}
I would like to extract this JSON into this format using SQL in BigQuery.
Note, the header id isn't defined in the JSON.
doc_id
id
author
new
old
property
sender
222
1675223776617
aaa
2023-02-01
null
asd
wew
222
1675223776618
aaa
true
null
asd
ewew
222
1675223776619
bbb
ySk2btk7
null
qwe
yyy
I tried using the JSON_EXTRACT function without any success.

Answer 1

You might consider below approach using javascript UDF.
CREATE TEMP FUNCTION flatten_json(json STRING)
RETURNS ARRAY<STRUCT<id STRING, author STRING, new STRING, old STRING, property STRING, sender STRING>>
LANGUAGE js AS """
result = [];
for (const [key, value] of Object.entries(JSON.parse(json))) {
value["id"] = key; result.push(value);
}
return result;
""";
WITH sample_table AS (
SELECT 222 doc_id, '''{
"1675223776617": {
"author": "aaa",
"new": "2023-02-01",
"old": null,
"property": "asd",
"sender": "wew"
},
"1675223776618": {
"author": "aaa",
"new": true,
"old": null,
"property": "asd",
"sender": "ewew"
},
"1675223776619": {
"author": "bbb",
"new": "ySk2btk7",
"old": null,
"property": "qwe",
"sender": "yyy"
}
}''' data
)
SELECT doc_id, flattened.*
FROM sample_table, UNNEST(flatten_json(json)) flattened;
Query results