Github user cestella commented on a diff in the pull request:
https://github.com/apache/metron/pull/727#discussion_r136594535
--- Diff:
metron-stellar/stellar-common/src/main/java/org/apache/metron/stellar/dsl/functions/StringFunctions.java
---
@@ -450,4 +454,40 @@ public Object apply(List<Object> strings) {
}
}
+ @Stellar( name = "PARSE_JSON_STRING"
+ , description = "Returns a JSON object for the specified JSON
string"
+ , params = {
+ "str - the JSON String to convert, may be null"
+ }
+ , returns = "an Object containing the parsed JSON string"
+ )
+ public static class ParseJsonString extends BaseStellarFunction {
+
--- End diff --
So, the usecase is having an enrichment which stores a JSON blob in HBase
(or some other store) that you want to marshall into a Java object to interact
with via stellar. Some people would prefer to have their data in a readable
format rather than serialized via kryo (like we do in the profiler) or
restricted to a certain format (like we do in enrichments). This opens up
those use-cases.
That JSON blob may be a map or a list or a primitive; the idea is to let
jackson handle the parsing of it, so the bounds are what JSON can represent.
The knowledge of what is returned would be necessary for the caller, though, as
you say.
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