Ereli Ereli - 2 months ago 19
JSON Question

Escaping Characters in Bigquery json_extract() function

when using Google's BigQuery, there's a function that can extract elements from json strings using jsonPath. For example:

SELECT JSON_EXTRACT(data,"$.key.value") AS feature FROM tablename


when the json key itself contains a dot,
{"key.value":"value"}
It's not clear how to escape that properly.

this jsonpath message board question says that jsonpath itself supports this format

@Test
public void path_with_bracket_notation() throws Exception {
String json = "{\"foo.bar\": {\"key\": \"value\"}}";

Assert.assertEquals("value", JsonPath.read(json, "$.['foo.bar'].key"));


However in bigquery this type of espcaping attempts cause
Error: JSONPath parse error
errors.

Answer

Update, new answer:

BigQuery's JSON_EXTRACT and JSON_EXTRACT_SCALAR functions now support JSON bracket notation in JSONPath, so the following query works:

SELECT JSON_EXTRACT('{"key.value": {"foo": "bar"}}', "$['key.value']")

and returns

{"foo":"bar"}

Old, now outdated answer:

Unfortunatelly BigQuery does not support escaping special characters in json path. The workaround would be to use REPLACE function to convert dots to underscores, i.e.

SELECT 
  json_extract(
    replace('{"key.value":"value"}',
    'key.value',
    'key_value'),
  '$.key_value')