BigQuery支持哪些JsonPath表达式？

Question

我在BigQuery 文档中读到，它支持JsonPath表达式语言的子集。但我无法找到它JsonPath的部分，实际上是支持？例如，当我在控制台中尝试时，在BigQuery的JsonPath表达式中似乎无法使用通配符或过滤器。

1. 是否可以在BigQuery的JsonPath表达式中使用通配符和过滤器？
2. 是否有参考文档或其他文档描述了BigQuery中对JsonPath 的完整支持（因为我似乎找不到它）？

Answer 1

是否可以在BigQuery的JsonPath表达式中使用通配符和过滤器？

为了克服JsonPath的BigQuery“局限性”，可以引入自定义功能，如下例所示：
注意：它使用jsonpath-0.8.0.js，可以从https://code.google.com/archive/p/jsonpath下载/ downloads并上传到Google Cloud Storage-gs：//your_bucket/jsonpath-0.8.0.js

#standardSQL
CREATE TEMPORARY FUNCTION CUSTOM_JSON_EXTRACT(json STRING, json_path STRING)
RETURNS STRING
LANGUAGE js AS """
    try { var parsed = JSON.parse(json);
        return JSON.stringify(jsonPath(parsed, json_path));
    } catch (e) { return null }
"""
OPTIONS (
    library="gs://your_bucket/jsonpath-0.8.0.js"
);
WITH t AS (
SELECT '''
{ "store": {
        "book": [ 
            { "category": "reference",
                "author": "Nigel Rees",
                "title": "Sayings of the Century",
                "price": 8.95
            },
            { "category": "fiction",
                "author": "Evelyn Waugh",
                "title": "Sword of Honour",
                "price": 12.99
            },
            { "category": "fiction",
                "author": "Herman Melville",
                "title": "Moby Dick",
                "isbn": "0-553-21311-3",
                "price": 8.99
            },
            { "category": "fiction",
                "author": "J. R. R. Tolkien",
                "title": "The Lord of the Rings",
                "isbn": "0-395-19395-8",
                "price": 22.99
            }
        ],
        "bicycle": {
            "color": "red",
            "price": 19.95
        }
    }
}
''' AS x
)
SELECT 
    CUSTOM_JSON_EXTRACT(x, '$.store.book[*].author'),
    CUSTOM_JSON_EXTRACT(x, '$..*[?(@.price==22.99)].author'),
    CUSTOM_JSON_EXTRACT(x, '$..author'),
    CUSTOM_JSON_EXTRACT(x, '$.store.*'),
    CUSTOM_JSON_EXTRACT(x, '$.store..price'),
    CUSTOM_JSON_EXTRACT(x, '$..book[(@.length-1)]'),
    CUSTOM_JSON_EXTRACT(x, '$..book[-1:]'),
    CUSTOM_JSON_EXTRACT(x, '$..book[0,1]'),
    CUSTOM_JSON_EXTRACT(x, '$..book[:2]'),
    CUSTOM_JSON_EXTRACT(x, '$..book[?(@.isbn)]')
FROM t

结果如下

对于 CUSTOM_JSON_EXTRACT(x, '$.store.book[*].author')

[
  "Nigel Rees"
  "Evelyn Waugh"
  "Herman Melville"
  "J. R. R. Tolkien"
]

对于 CUSTOM_JSON_EXTRACT(x, '$..*[?(@.price==22.99)].author')

[
  "J. R. R. Tolkien"
]  

对于 CUSTOM_JSON_EXTRACT(x, '$.store..price')

[
  8.95
  12.99
  8.99
  22.99
  19.95
]

等等 ...

如您所见-现在您可以使用通配符和过滤器以及所有jazz：o）