Merging two JSON files while summing up values - mule-studio

Question

I get two different files with stock information which I would like to join into one file while summing the data up, based on "pid".
payloadA
{
"order": [
{
"pid": "a",
"instock": "2"
},
{
"pid": "b",
"instock": "2"
},
{
"pid": "c",
"instock": "2"
}
]
}
payloadB
{
"order": [
{
"pid": "c",
"instock": "2"
},
{
"pid": "d",
"instock": "2"
}
]
}
Result
payloadA
{
"order": [
{
"pid": "a",
"instock": "2"
},
{
"pid": "b",
"instock": "2"
},
{
"pid": "c",
"instock": "4"
},
{
"pid": "c",
"instock": "2"
}
]
}
But what I'm struggeling with are the edge cases:
pids might be in both or as well in only one of the datasets
payloadB might be empty
{
"order": []
}

Answer 1

You can try the following DataWeave expression:
%dw 2.0
output application/json
import * from dw::core::Arrays
var payloadA = {
"order": [
{
"pid": "a",
"instock": "2"
},
{
"pid": "b",
"instock": "2"
},
{
"pid": "c",
"instock": "2"
}
]
}
var payloadB = {
"order": [
{
"pid": "c",
"instock": "2"
},
{
"pid": "d",
"instock": "2"
}
]
}
---
"order": outerJoin(payloadA.order, payloadB.order, (itemA) -> itemA.pid, (itemB) -> itemB.pid) map (item, index) -> {
"pid": item.l.pid default item.r.pid,
"instock": (item.l.instock default 0) + (item.r.instock default 0)
}
Output:
{
"order": [
{
"pid": "a",
"instock": 2
},
{
"pid": "b",
"instock": 2
},
{
"pid": "c",
"instock": 4
},
{
"pid": "d",
"instock": 2
}
]
}