Modify nested arrays in JSON (Groovy) - json

Question

I'm trying to parse and mofidy JSON with Groovy. Source JSON from REST API looks like:
[
{
"id":27858,
"type":"ad",
"stats":[
{
"day":"2021-01-21",
"sex":[
{
"impressions_rate":0.349,
"value":"f"
},
{
"impressions_rate":0.621,
"value":"m",
"clicks_rate":0.22
}
],
"age":[
{
"impressions_rate":0.217,
"value":"18-21"
}
]
},
{
"day":"2021-02-25",
"sex":[
{
"impressions_rate":0.349,
"value":"f"
},
{
"impressions_rate":0.651,
"value":"m"
}
],
"age":[
{
"impressions_rate":0.217,
"value":"18-21"
}
]
}
]
},
{
"id":565291,
"type":"ad",
"stats":[
{
"day":"2021-03-21",
"sex":[
{
"impressions_rate":0.78,
"value":"f",
"clicks_rate":0.33
},
{
"impressions_rate":0.551,
"value":"m"
}
],
"age":[
{
"impressions_rate":0.17,
"value":"18-21"
}
]
}
]
}
]
It's an array with some ids and data for them. I want to grab id, day inside stats array and elements from sex array. After all manipulations my JSON should be like this:
[
{
"id": 27858,
"day": "2021-01-21",
"impression_rate": 0.349,
"value": "f"
},
{
"id": 27858,
"day": "2021-01-21",
"impression_rate": 0.621,
"value": "f",
"clicks_rate": 0.22
},
{
"id": 27858,
"day": "2021-02-25",
"impressions_rate":0.349,
"value":"f"
},
{
"id": 27858,
"day": "2021-02-25",
"impressions_rate":0.651,
"value":"m"
},
{
"id": 565291,
"day": "2021-03-21",
"impressions_rate":0.78,
"value":"f",
"clicks_rate":0.33
},
{
"id": 565291,
"day": "2021-03-21",
"impressions_rate":0.78,
"value":"f",
"clicks_rate":0.33
}
]
So, the main goal is - loop through all ids -> elements in sex array (for each id) and add to these elements day and id mapped fields. I tried to start with empty map with inject, but after 1 hour of debugging i still can't achieve desired output, so maybe better to loop through existed values in array? But I can't even reach sex array.
import groovy.json.*
def json = new JsonSlurper().parseText '''...'''
List expected = json.inject([]){ r, e ->
Map ids = e.findAll {
k, v -> k == "id"
}
e.each{ k, v ->
if( (v.any{ it.sex } )
v.each{ r << ids + it }
}
return r
}

Answer 1

If you have nested structures, that contain again nested structures,
a good option, to get a flat result, is to use collectMany; like
collect it transforms each item of the iterated container, but the
results gets concated.
E.g. you can collectMany on your outer data, then again on the
stats, and finally just collect over sex.
def data = new groovy.json.JsonSlurper().parse("data.json" as File)
println data.collectMany{ o ->
o.stats.collectMany{ i ->
i.sex.collect{ it + [id: o.id, day: i.day] }
}
}
// [[impressions_rate:0.349, value:f, id:27858, day:2021-01-21],
// [impressions_rate:0.621, value:m, clicks_rate:0.22, id:27858, day:2021-01-21],
// [impressions_rate:0.349, value:f, id:27858, day:2021-02-25],
// [impressions_rate:0.651, value:m, id:27858, day:2021-02-25],
// [impressions_rate:0.78, value:f, clicks_rate:0.33, id:565291, day:2021-03-21],
// [impressions_rate:0.551, value:m, id:565291, day:2021-03-21]]