How to convert string representation dictionary into struct in gcp bigquery? - google-bigquery

Question

How can actually convert the below string into STRUCT
select '{\"ID\": \"A\", \"QualifierID\": \"XYZ\", \"text\": \"Origin\"}';
I want the above string formatted text to be Struct type in GCP Bigquery.

Answer 1

Using a JSON function,
WITH sample_data AS (
SELECT '{\"ID\": \"A\", \"QualifierID\": \"XYZ\", \"text\": \"Origin\"}' json
)
SELECT STRUCT (
JSON_VALUE(json, '$.ID') AS ID,
JSON_VALUE(json, '$.QualifierID') AS QualifierID,
JSON_VALUE(json, '$.text') AS text
) AS struct_col
FROM sample_data;
Or with JSON type,
WITH sample_data AS (
SELECT '{\"ID\": \"A\", \"QualifierID\": \"XYZ\", \"text\": \"Origin\"}' json
)
SELECT STRUCT (
STRING(PARSE_JSON(json).ID) AS ID,
STRING(PARSE_JSON(json).QualifierID) AS QualifierID,
STRING(PARSE_JSON(json).text) AS text
) AS struct_col
FROM sample_data;
you can get following result:

Answer 2

Consider yet another option
create temp function keys(input string) returns array<string> language js as """
return Object.keys(JSON.parse(input));
""";
create temp function values(input string) returns array<string> language js as """
return Object.values(JSON.parse(input));
""";
select * except(row_id) from (
select to_json_string(t) row_id, key, value
from your_table t, unnest(keys(json)) key with offset
join unnest(values(json)) value with offset
using(offset)
)
pivot (any_value(value) for key in ('ID', 'QualifierID', 'text'))
if applied to sample data in your question - output is

Answer 3

Does something like this work for you?
with _cte as (
select JSON '{\"ID\": \"A\", \"QualifierID\": \"XYZ\", \"text\": \"Origin\"}' as tojson
)
select struct(JSON_EXTRACT(tojson, '$.ID') as ID,
JSON_EXTRACT(tojson, '$.QualifierID') as QualifierID,
JSON_EXTRACT(tojson, '$.text') as text) as tostruct
from _cte