How to repeat multiple lists inside data weave in mule - json

Question

The problem i am facing is with repeating multiple lists inside dataweave.
input of the dataweave --> coming in two flow varibles (as below),
var1: [{bkAuthorID=1, bkAuthorName=abc, bookCategory=horror}, {bkAuthorID=2, bkAuthorName=xyz, bookCategory=horror}, {bkAuthorID=1, bkAuthorName=abc, bookCategory=comedy}, {bkAuthorID=2, bkAuthorName=xyz, bookCategory=Fantacy}}]
var2: [{bkAuthorID=1, bkName=gjh, bkDescription=kjh},{bkAuthorID=1, bkName=sfs, bkDescription=kjh},{bkAuthorID=2, bkName=gjh, bkDescription=kjh},{bkAuthorID=2, bkName=gjh, bkDescription=kjh}]
output in dataweave --> desired json structue with three lists is like below.
{
"books": [
{
"bookAuthor": "abc",
"bookCategorys": [
{
"bookCategory": "horror",
"listOfBooks": [
{
"bookName": "xyz",
"bookDescription":"lmn"
},
{
"bookName": "xyz",
"bookDescription":"lmn"
}
]
},
{
"bookCategory": "comedy",
"listOfBooks": [
{
"bookName": "xyz",
"bookDescription":"lmn"
}
]
}
]
},
{
"bookAuthor": "xyz",
"bookCategorys": [
{
"bookCategory": "horror",
"listOfBooks": [
{
"bookName": "xyz",
"bookDescription":"lmn"
}
]
}
]
}
]
}
Can anyone help on this dataweave mapping for this requirement.
#Manik, can you please help me out.

Answer 1

I am able to establish relation between var1 and var2 using bkAuthorID.
But, there has to be one more relation to tell which book in var2 belongs to which category. Hence, in the below output, each category will have list of all the books written by that author. Anyways, all you need to do is just add one more filter condition in 'listOfBooks' line.
Dataweave code:
%dw 1.0
%output application/json
---
{
books:( flowVars.var1 groupBy $.bkAuthorName map using (authorId=$.bkAuthorID[0]) {
bookAuthor:$[0].bkAuthorName,
bookCategorys: $ groupBy $.bookCategory map {
bookCategory:$.bookCategory[0],
listOfBooks: flowVars.var2[?($.bkAuthorID == authorId)] map {
bookName:$.bkName,
bookDescription:$.bkDescription
}
}
})
}
Output:
{
"books": [
{
"bookAuthor": "abc",
"bookCategorys": [
{
"bookCategory": "horror",
"listOfBooks": [
{
"bookName": "gjh",
"bookDescription": "kjh"
},
{
"bookName": "sfs",
"bookDescription": "kjh"
}
]
},
{
"bookCategory": "comedy",
"listOfBooks": [
{
"bookName": "gjh",
"bookDescription": "kjh"
},
{
"bookName": "sfs",
"bookDescription": "kjh"
}
]
}
]
},
{
"bookAuthor": "xyz",
"bookCategorys": [
{
"bookCategory": "horror",
"listOfBooks": [
{
"bookName": "gjh",
"bookDescription": "kjh"
},
{
"bookName": "gjh",
"bookDescription": "kjh"
}
]
},
{
"bookCategory": "Fantacy",
"listOfBooks": [
{
"bookName": "gjh",
"bookDescription": "kjh"
},
{
"bookName": "gjh",
"bookDescription": "kjh"
}
]
}
]
}
]
}