JSON_EXTRACT in BigQuery Standard SQL? - google-bigquery

Question

I'm converting some SQL code from BigQuery to BigQuery Standard SQL.
I can't seem to find JSON_EXTRACT_SCALAR in Bigquery Standard SQL, is there an equivalent?

Answer 1

Edit: we implemented the JSON functions a while back. You can read about them in the documentation.

Answer 2

Not that I know of, but there is always workaround
Let's assume we want to mimic example from JSON_EXTRACT_SCALAR documentation
SELECT JSON_EXTRACT_SCALAR('{"a": ["x", {"b":3}]}', '$.a[1].b') as str
Below code does same
CREATE TEMPORARY FUNCTION CUSTOM_JSON_EXTRACT(json STRING)
RETURNS STRING
LANGUAGE js AS """
try { var parsed = JSON.parse(json);
} catch (e) { return null }
return parsed.a[1].b;
""";
SELECT CUSTOM_JSON_EXTRACT('{"a": ["x", {"b":3}]}') AS str
I think this can be good starting point to experiment with
see more for Scalar UDF in BigQuery Standard SQL
Quick update
After cup of coffee, decided to complete this "exercise" by myself
Look as a good short term solution to me :o)
CREATE TEMPORARY FUNCTION CUSTOM_JSON_EXTRACT(json STRING, json_path STRING)
RETURNS STRING
LANGUAGE js AS """
try { var parsed = JSON.parse(json);
} catch (e) { return null }
return eval(json_path.replace("$", "parsed"));
""";
SELECT
CUSTOM_JSON_EXTRACT('{"a": ["x", {"b":3}]}', '$.a[1].b') AS str1,
CUSTOM_JSON_EXTRACT('{"a": ["x", {"b":3}]}', '$.a[0]') AS str2,
CUSTOM_JSON_EXTRACT('{"a": 1, "b": [4, 5]}', '$.b') AS str3