如何从 BigQuery 中的列解析 JSON 文件

Question

This is the JSON file that I am trying to parse

[{"message":"Value","code":"1234"}]

I am trying to parse the message from the JSON I think the challenge is because the JSON started with "[" instead of the more common "{"

This is the query that I thought was right but apparently it's not

JSON_EXTRACT_SCALAR(response,'$[0].message')

Please note that "response" is the name of the column aka the json_string_expr

Answer 1

Might be a typo in your real code/query?
Works for me as is - see example below

#standardSQL
WITH `project.dataset.table` AS (
  SELECT '[{"message":"Value","code":"1234"}]' response
)
SELECT *, JSON_EXTRACT_SCALAR(response,'$[0].message')
FROM `project.dataset.table`

with output

Row response                            f0_  
1   [{"message":"Value","code":"1234"}] Value   

Answer 2

You can apply:

WITH `project.dataset.table` AS (
  SELECT '{\n \"type\":\"invalid\",\n \"code\":\"invalidRequest\",\n \"details\":\"Missing or invalid Parameters\",\n \"moreInfo\":{\n \"fieldLevelErrors\":[\n {\n \"fieldName\":\"/*/prospect/identificationDocumentDetails[idType!=\\\"\\\"]/idNumber\",\n \"reasonCode\":\"Required/Invalid Format\",\n \"errorMessage\":\"Value\"\n }\n ]\n }\n}' response
)
SELECT JSON_EXTRACT(response,'$.details') as details, JSON_EXTRACT(response,'$.moreInfo.fieldLevelErrors[0].errorMessage') as error
FROM `project.dataset.table`

It returns the following result:

Row details                           error 
1   "Missing or invalid Parameters" "Value"