BigQuery - nested json - select where nested item equals - sql

Question

Having the following table in BigQuery database, where the f0_
Row | f0_
1 | {"configuration":[{"param1":"value1"},{"param2":[3.0,45]}]}
2 | {"configuration":[{"param1":"value2"},{"param2":[3.0,45]}]}
3 | {"configuration":[{"param1":"value1"},{"param2":[3.0,36]}]}
4 | {"configuration":[{"param1":"value1"},{"param2":[3.0,46]}]}
5 | {"configuration":[{"param1":"value1"},{"param2":[3.0,30]}]}
6 | {"configuration":[{"param1":"value1"}]}
f0_ column is a pure string.
Is there a way to write a select query, where the "param2" value is equal to [3.0, 45] array meaning it would only return rows 1 and 2? Preferably would be great to accomplish it without directly indexing the first element in the "configuration" array as the order might not be guaranteed.

Answer 1

Below is for BigQuery Standrad SQL
#standardSQL
SELECT line
FROM `project.dataset.table`
WHERE REGEXP_EXTRACT(JSON_EXTRACT(line, '$.configuration'), r'{"param2":(.*?)}') = '[3.0,45]'
You can test, play with above using sample data from your question as in example below
#standardSQL
WITH `project.dataset.table` AS (
SELECT '{"configuration":[{"param1":"value1"},{"param2":[3.0,45]}]}' line UNION ALL
SELECT '{"configuration":[{"param1":"value2"},{"param2":[3.0,45]}]}' UNION ALL
SELECT '{"configuration":[{"param1":"value1"},{"param2":[3.0,36]}]}' UNION ALL
SELECT '{"configuration":[{"param1":"value1"},{"param2":[3.0,46]}]}' UNION ALL
SELECT '{"configuration":[{"param1":"value1"},{"param2":[3.0,30]}]}' UNION ALL
SELECT '{"configuration":[{"param1":"value1"}]}'
)
SELECT line
FROM `project.dataset.table`
WHERE REGEXP_EXTRACT(JSON_EXTRACT(line, '$.configuration'), r'{"param2":(.*?)}') = '[3.0,45]'
with result
Row line
1 {"configuration":[{"param1":"value1"},{"param2":[3.0,45]}]}
2 {"configuration":[{"param1":"value2"},{"param2":[3.0,45]}]}
Preferably would be great to accomplish it without directly indexing the first element in the "configuration" array as the order might not be guaranteed.
Note: this solution does not depend on position of "param2" in the configuration array

Answer 2

You can use some of BQ's neat JSON functions as described here.
Based on that, you can locate param2 and check if its value matches what you're looking for. If you aren't sure of the configuration order, you can iterate through the array to find param2, but it's not particularly efficient. I recommend you try to find a way where param2 is always the second field in the array. I was able to get the correct results like so:
SELECT json_text AS correct_configurations
FROM UNNEST([
'{"configuration":[{"param1":"value1"},{"param2":[3.0,45]}]}',
'{"configuration":[{"param1":"value2"},{"param2":[3.0,45]}]}',
'{"configuration":[{"param1":"value1"},{"param2":[3.0,36]}]}',
'{"configuration":[{"param1":"value1"},{"param2":[3.0,46]}]}',
'{"configuration":[{"param1":"value1"},{"param2":[3.0,30]}]}',
'{"configuration":[{"param1":"value1"}]}'
])
AS json_text
WHERE JSON_EXTRACT(json_text, '$.configuration[1].param2') LIKE "[3.0,45]";
Gives a result of:
Row | correct_configurations
1 | {"configuration":[{"param1":"value1"},{"param2":[3.0,45]}]}
2 | {"configuration":[{"param1":"value2"},{"param2":[3.0,45]}]}