What is the syntax for json path?

[hamlet-lee]

create table temp.test_explode (userid string, log string) partitioned by (day string) stored as orc;
insert into table temp.test_explode partition (day = '2017-11-01') values ('u1', '[{  "action": "a" },  {  
"action": "b"} ]');
insert into table temp.test_explode partition (day = '2017-11-02') values ('u2', '[{  "action": "a" , "arg1": "1"},  {  "action": "b", "arg2": "2"} ]');


create temporary function udf_json_array_extract as 'cc.shanruifeng.functions.json.UDFJsonArrayExtract';

create temporary function udf_json_array_extract_scalar as 'cc.shanruifeng.functions.json.UDFJsonExtractScalar';


select userid, udf_json_array_extract ( log, '$.action' ) from  temp.test_explode  where day = '2017-11-01';

-- result
u1	["\"a\"","\"b\""]

select userid, udf_json_array_extract_scalar ( log, '$.action' ) from  temp.test_explode  where day = '2017-11-01';

-- result
u1	NULL

I want to get an array like ["a","b"], in the above second query, I got NULL.

Am I using wrong syntax for json path? What is the syntax for the path?

[aaronshan]

@hamlet-lee your udf function define error.
you should change UDFJsonExtractScalar to UDFJsonArrayExtractScalar . like this:

create temporary function udf_json_array_extract_scalar as 'cc.shanruifeng.functions.json.UDFJsonArrayExtractScalar';

[hamlet-lee]

@aaronshan Thanks, I will try later