How to Generate an Array of Objects with Nested Siblings with Groovy JsonBuilder

Question

I'm trying to generate a JSON array with multiple nested objects.

Here's what I'd like to generate: (shortened output since I want an array, this just repeats if you run the code):

[
    {
        "User": {
            "Name": "Foo",
            "Email": "test@example.com"
        },
        "Details": {
            "Address": {
                "City": "Anywhere",
                "Country": "USA",
                "State": "ID",
                "ZipCode": "55842"
            },
            "FavoriteColor": "Blue"            
        }
    }
]

Instead I'm generating this:

[
        {
            "User": {
                "Name": "Foo",
                "Email": "test@example.com"
            },
            "Address": {
                "City": "Anywhere",
                "Country": "USA",
                "State": "ID",
                "ZipCode": "55842"
            },
            "Details": [
                {
                    "FavoriteColor": "Blue"
                },
                {
                    "City": "Anywhere",
                    "Country": "USA",
                    "State": "ID",
                    "ZipCode": "55842"
                }
            ]
        }
    ]

Here's my code:

def array = 1..3

def builder = new groovy.json.JsonBuilder()
builder array.collect { itemNumber ->
    [{
        User(
            Name: "Foo" + itemNumber,
            Email: "test@example.com"
        )
        Details(
            Address(
                City: "Anywhere",
                Country: "USA",
                State: "ID",
                ZipCode: "55842"
            ),
            FavoriteColor: "Blue"
        )
    }
    ]
}

println groovy.json.JsonOutput.prettyPrint(builder.toString())

Do you really need jsonbuilder? Why not to use plain maps/arrays? — daggett, Dec 17 '19 at 04:04
Problem in your code that function `address` need to be called before function `details` — daggett, Dec 17 '19 at 04:08

score 2 · Accepted Answer · answered Dec 17 '19 at 09:23

Like mentioned in the comments, in my experience it's better to stay with lists and maps in groovy and only convert to json as a final step. This way you get to use all the groovy goodness for handling maps and lists (collect, findAll, groupBy, etc) to mutate your data and then as a final step generate your json.

Example code:

import groovy.json.JsonOutput

def numbers = 1..3

def data = numbers.collect { n -> 
  [
    User: [
      Name: "Foo${n}", 
      Email: "test@example.com"
    ],
    Details: [
      Address: [
        City:     "Anywhere", 
        Country:  "USA", 
        State:    "ID", 
        ZipCode:  "55842"
      ],
      FavoriteColor: "Blue"
    ]
  ]
}

def json   = JsonOutput.toJson(data)
def pretty = JsonOutput.prettyPrint(json)
println "JSON:\n${pretty}"

when run it generates:

─➤ groovy solution.groovy
JSON:
[
    {
        "User": {
            "Name": "Foo1",
            "Email": "test@example.com"
        },
        "Details": {
            "Address": {
                "City": "Anywhere",
                "Country": "USA",
                "State": "ID",
                "ZipCode": "55842"
            },
            "FavoriteColor": "Blue"
        }
    },
    {
        "User": {
            "Name": "Foo2",
            "Email": "test@example.com"
        },
        "Details": {
            "Address": {
                "City": "Anywhere",
                "Country": "USA",
                "State": "ID",
                "ZipCode": "55842"
            },
            "FavoriteColor": "Blue"
        }
    },
    {
        "User": {
            "Name": "Foo3",
            "Email": "test@example.com"
        },
        "Details": {
            "Address": {
                "City": "Anywhere",
                "Country": "USA",
                "State": "ID",
                "ZipCode": "55842"
            },
            "FavoriteColor": "Blue"
        }
    }
]

A note on map keys in groovy, I did not quote mine above because when your keys are valid identifiers (i.e. not something like Favourite-Color) you don't need quotes. If you run into keys that break the above pattern, you can always quote the keys.

How to Generate an Array of Objects with Nested Siblings with Groovy JsonBuilder

1 Answers1