How to parse JSON in Standard SQL BigQuery? - sql

Question

After streaming some json data into BQ, we have a record that looks like:
"{\"Type\": \"Some_type\", \"Identification\": {\"Name\": \"First Last\"}}"
How would I extract the type from this? E.g. I would like to get Some_type.
I tried all possible combinations shown in https://cloud.google.com/bigquery/docs/reference/standard-sql/json_functions without success, namely, I thought:
SELECT JSON_EXTRACT_SCALAR(raw_json , "$[\"Type\"]") as parsed_type FROM `table` LIMIT 1000
is what I need. However, I get:
Invalid token in JSONPath at: ["Type"]
Picture of rows preview

Answer 1

Below example is for BigQuery Standard SQL
#standardSQL
WITH `project.dataset.table` AS (
SELECT 1 id, "{\"Type\": \"Some_type\", \"Identification\": {\"Name\": \"First Last\"}}" raw_json UNION ALL
SELECT 2, '{"Type": "Some_type", "Identification": {"Name": "First Last"}}'
)
SELECT id, JSON_EXTRACT_SCALAR(raw_json , "$.Type") AS parsed_type
FROM `project.dataset.table`
with result
Row id parsed_type
1 1 Some_type
2 2 Some_type
See below update example - take a look at third record which I think mimic your case
#standardSQL
WITH `project.dataset.table` AS (
SELECT 1 id, "{\"Type\": \"Some_type\", \"Identification\": {\"Name\": \"First Last\"}}" raw_json UNION ALL
SELECT 2, '''{"Type": "Some_type", "Identification": {"Name": "First Last"}}''' UNION ALL
SELECT 3, '''"{\"Type\": \"
null1\"}"
'''
)
SELECT id,
JSON_EXTRACT_SCALAR(REGEXP_REPLACE(raw_json, r'^"|"$', '') , "$.Type") AS parsed_type
FROM `project.dataset.table`
with result
Row id parsed_type
1 1 Some_type
2 2 Some_type
3 3 null1
Note: I use null1 instead of null so you can easily see that it is not a NULL but rather string null1