How to transform JSON response retrieved from external system to meaningful data (key/value pairs) in ESQL?
Retrieved JSON:
{
"data": [
{
"name": "application.info.header",
"value": "headerValue"
},
{
"name": "entity.statistics.name.fullName",
"value": "fullNameValue"
},
{
"name": "application.info.matter",
"value": "matterValue"
},
{
"name": "entity.statistics.skill",
"value": "skillValue"
}
]
}
where,
name
~ hierarchy of JSON (last attribute being the key)
value
~ value against the key
Expected JSON:
{
"data": {
"application": {
"info": {
"header": "headerValue",
"matter": "matterValue"
}
},
"entity": {
"statistics": {
"name": {
"fullName": "fullNameValue"
},
"skill": "skillValue"
}
}
}
}
Needless to say this can be easily achieved in Java through Split
method - I'm looking for a suitable method in ESQL.
Current ESQL Module:
CREATE COMPUTE MODULE getDetails_prepareResponse
CREATE FUNCTION Main() RETURNS BOOLEAN
BEGIN
DECLARE data REFERENCE TO InputRoot.JSON.Data.data.Item[1];
SET OutputRoot.JSON.Data = InputRoot.JSON.Data;
SET OutputRoot.JSON.Data.data = NULL;
WHILE LASTMOVE(data) DO
DECLARE keyA CHARACTER SUBSTRING(data.name BEFORE '.');
DECLARE name CHARACTER SUBSTRING(data.name AFTER '.');
DECLARE keyB CHARACTER SUBSTRING(name BEFORE '.');
DECLARE key CHARACTER SUBSTRING(name AFTER '.');
CREATE LASTCHILD OF OutputRoot.JSON.Data.data.{EVAL('keyA')}.{EVAL('keyB')}
NAME key VALUE data.value;
MOVE data NEXTSIBLING;
END WHILE;
RETURN TRUE;
END;
END MODULE;
This is currently handled through SUBSTRING
method in ESQL (for 3 levels only), but now the JSON levels are dynamic (no limit to key/value pairs) as per requirements.
You could implement your own procedure to split a string. Take a look at this answer for an example.
ESQL for splitting a string into mulitple values
The method splits S on Delim into an array in Env (Environment.Split.Array[]) and removes Environment.Split before refilling it.