Escaping Bigquery json_extract() 中的字符 function

Question

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 1

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Old, now outdated answer: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, ie

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

Answer 2

use backtick to escape (it is also used to escape hyphen in project/dataset name)

SELECT JSON_VALUE(json_field.`key.value`) AS feature FROM tablename