String conversion in hive - json

Question

I have a json string in which there isa field called version.
Version can either not be there or if it is there it will be of form x.y
.
I want to convert this to x.0 I am currently doing
CONCAT(split(get_json_object(json, '$.version'),'[.]')[0],".","0")
but this does not handle cases where version is not there.
I want "bad_version" to be returned if version is not there. Can I somehow use COALESCE and do some tweaks ?

Answer 1

Yes, you can use either COALESCE or CASE - the syntax is identical to database usage.
select coalesce(myField, 'bad_version') ....
or
select case when myField is null then 'bad_version' else myField end as x ....

Answer 2

You can conditionally test the result of get_json_object to see if it's NULL and return bad_version accordingly. When the version is valid, you can use a regular expression to replace the minor version with 0.
SELECT
IF(get_json_object(json, "$.version") IS NULL,
"bad_version",
regexp_replace(get_json_object(json, "$.version") , "\\..*$", ".0")
)
FROM json_table; -- The table I loaded with test data
Some simple example data:
hive> SELECT json FROM json_table;
OK
{"id":"001","version":"3.9"}
{"id":"002","notversion":"3.9"}
Time taken: 0.225 seconds, Fetched: 2 row(s)
And then the results of this query against this data:
hive> SELECT
> IF(get_json_object(json, "$.version") IS NULL,
> "bad_version",
> regexp_replace(get_json_object(json, "$.version") , "\\..+$", ".0")
> )
> FROM json_table;
OK
3.0
bad_version
Time taken: 0.225 seconds, Fetched: 2 row(s)