transform list to list of maps in Groovy

Question

Can anyone help to convert a list to list of Maps in Groovy ?

I have a list as below

[war, jar]

and a variable with name "value" = 2.0.0

I want to convert this into a list with maps [["pack": "war", "ver": "2.0.0"],["pack": jar, "ver": "2.0.0"]]

and create a json.

{
    "ProjectId": "Projects-16",
    "ChannelId": "Channels-41",
    "Version": "2.0.1.0-10",
    "selectedPackages": [{"pack": "war", "ver": "2.0.0"}, {"pack": jar, "ver": "2.0.0"]}]
}

Please add the code you have tried and how it failed (e.g. errors, stacktraces, logs, ...) so we can improve on it. Have you tried collect or collectEntries? — cfrick
– cfrick, Commented Feb 16, 2021 at 11:45
Also ["war": "2.0.0", "jar": "2.0.0"] is not the same as [{"war": "2.0.0"}, {"jar": "2.0.0"}] — cfrick
– cfrick, Commented Feb 16, 2021 at 11:46
yes. I tired collect and able to form ["war": "2.0.0", "jar": "2.0.0"] but i'm not sure how i can convert everything into json. — Sri
– Sri, Commented Feb 16, 2021 at 11:50
Then why is your question phrased like you have problems building a map/list of maps, when your actual problem is something different? Have you looked into JsonOutput to create JSON? — cfrick
– cfrick, Commented Feb 16, 2021 at 11:52
Because, i'm not sure if the map I created is correct or not. As you pointed out ["war": "2.0.0", "jar": "2.0.0"] is not the same as [{"war": "2.0.0"}, {"jar": "2.0.0"}]. I also tried list.collect { it -> "{$it: ${value}}" } which gives [{jar: 4.0}, {war: 4.0}]. But when i used JsonBuilder to convert into json, it converts as { "channelId": "Channels-41", "selectedPackages": [ "war: 2.0.0.","jar:2.0.0" ], "version": "2.0.0.7-10", "projectId": "Projects-16" } — Sri
– Sri, Commented Feb 16, 2021 at 12:05

Catalin · Accepted Answer · 2021-02-19 22:08:03Z

1

Here is the solution:

import groovy.json.JsonOutput

def packages = ["war", "jar"]
def value = "2.0.0"
def list = packages.collect { [pack : it, ver : value] }
def object = [
    ProjectId: "Projects-16",
    ChannelId: "Channels-41",
    Version: "2.0.1.0-10",
    selectedPackages: list
]
def json = JsonOutput.toJson(object)
println JsonOutput.prettyPrint(json)

Each {} entity in JSON is a map in Groovy therefore the expected [{}, {}] is a list of maps. You need just to construct the right objects using collect with the right transformation.

Edit
I updated the solution to return the exact json output as desired using a list and the variable value.

The output is this:

{
    "ProjectId": "Projects-16",
    "ChannelId": "Channels-41",
    "Version": "2.0.1.0-10",
    "selectedPackages": [
        {
            "pack": "war",
            "ver": "2.0.0"
        },
        {
            "pack": "jar",
            "ver": "2.0.0"
        }
    ]
}

edited Feb 19, 2021 at 22:08

answered Feb 16, 2021 at 18:32

Catalin

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1 Comment

cfrick Over a year ago

It's no problem here, but GStrings make bad map keys. Better use [(it): ...] instead.

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