Question

我有一个字符串字段，其中包含从服务器发送的原始JSON数据。但是，该键包含括号，在尝试提取数据时似乎会导致问题。

数据样本：

{"Interview (Onsite)": "2015-04-06 16:58:28"}

提取尝试：

timestamp(max(json_extract_scalar(a.status_history, '$.Interview (Onsite)')))

（＆＃39; max＆＃39;函数用作status_history是重复字段）

错误：

JSONPath parse error at: (Onsite)

我尝试了多种逃避括号的常用方法，但它让我无处可去。

会欣赏有关如何规避的建议 - 除非我真的需要，否则我宁愿不诉诸正则表达式。

Answer 1

启用standard SQL（取消选中＆＃34;使用旧版SQL＆＃34;＆＃34;显示选项＆＃34;在UI中）后，您可以使用带引号的字符串作为JSON路径的一部分。例如：

SELECT
  CAST(JSON_EXTRACT_SCALAR(
    '{"Interview (Onsite)": "2015-04-06 16:58:28"}',
    "$['Interview (Onsite)']") AS TIMESTAMP) AS t;

修改：由于您的列是ARRAY<STRING>，因此您需要使用ARRAY子查询将JSON_EXTRACT_SCALAR应用于每个元素。例如：

WITH T AS (
  SELECT
    ['{"Interview (Onsite)": "2015-04-06 16:58:28"}',
     '{"Interview (Onsite)": "2015-11-16 08:09:10"}',
     '{"Interview (Onsite)": "2016-01-01 18:12:43"}']
     AS status_history UNION ALL
  SELECT
    ['{"Interview (Onsite)": "2016-06-25 07:01:45"}']
)
SELECT
  ARRAY (
    SELECT CAST(JSON_EXTRACT_SCALAR(history, "$['Interview (Onsite)']") AS TIMESTAMP)
    FROM UNNEST(status_history) AS history
  ) AS interview_times
FROM T;

或者，如果您不关心保留阵列的结构，您可以“平坦化”＃34;它有一个连接，它将为status_history的每个元素返回一行：

WITH T AS (
  SELECT
    ['{"Interview (Onsite)": "2015-04-06 16:58:28"}',
     '{"Interview (Onsite)": "2015-11-16 08:09:10"}',
     '{"Interview (Onsite)": "2016-01-01 18:12:43"}']
     AS status_history UNION ALL
  SELECT
    ['{"Interview (Onsite)": "2016-06-25 07:01:45"}']
)
SELECT
  CAST(JSON_EXTRACT_SCALAR(history, "$['Interview (Onsite)']") AS TIMESTAMP)
    AS interview_time
FROM T CROSS JOIN UNNEST(status_history) AS history;

另请参阅section of the migration guide on handling of repeated fields。

json_extract_scalar在键名中以括号失败

1 个答案: