JSON_EXTRACT return 空值

Question

我想在 BigQuery 中查询以下 JSON 字符串：

'{"_id":"xxxxx","description":"stuff","userId":"1234}, {"_id":"xxxxx","description":"stuff","userId":"1234}'

我正在尝试运行以下查询，但这不起作用：

WITH test AS (
  SELECT '{"_id":"xxxxx","description":"stuff","userId":"1234}' raw_json UNION ALL
  SELECT '{"_id":"xxxxx","description":"stuff","userId":"1234}'
)
select JSON_EXTRACT('raw_json', '$.userId') AS json_extract,
from test

为什么？

最终我想查询一个 JSON 字符串，该字符串作为字符串存储在云存储中。

Answer 1

在您的示例中存在一些引用问题：

查询中 raw_json 周围的单引号使 BQ 认为您正在查询字符串 'raw_json' 的 'userId' 字段。这个字符串没有这样的字段（它甚至没有正确格式化 json，我很惊讶没有引发错误），所以结果为空。

以下作品：

WITH test AS (
  SELECT '{"_id":"xxxxx","description":"stuff","userId":"1234"}' raw_json 
UNION ALL
  SELECT '{"_id":"xxxxx","description":"stuff","userId":"1234"}'
)
select JSON_EXTRACT(raw_json, '$.userId') AS json_extract,
from test

请注意，显然 recommended way 是使用 JSON_VALUE:

WITH test AS (
  SELECT '{"_id":"xxxxx","description":"stuff","userId":"1234"}' raw_json 
UNION ALL
  SELECT '{"_id":"xxxxx","description":"stuff","userId":"1234"}'
)
select JSON_VALUE(raw_json, '$.userId') AS json_extract,
from test

JSON_EXTRACT return 空值

JSON_EXTRACT return null value

sql

json

google-bigquery