How to convert String list to JSON Array Groovy - arrays

Question

This is the problem that I'm trying to resolve. I have a list of map that I want to convert into JSON array in Groovy.
The list is:
List<Map<String, String>> studentList = [{id=1,name=John,email=john#google.com},{id=2,name=Peter,email=peter#google.com},{id=3,name=James,email=james#google.com}]
Desired JSON output is:
{
students: [{
"id" = "1",
"name" = "John",
"contact": {
"email": "john#google.com"
}
}, {
"id" = "2",
"name" = "Peter",
"contact": {
"email": "peter#google.com"
}
}, {
"id" = "3",
"name" = "James",
"contact": {
"email": "james#google.com"
}
}
]
}
My code only generates 1 student. Can anyone help me please?
def builder = new JsonBuilder()
for (Map student: studentList) {
builder.students {
id student.id
name student.name
contact {
email student.email
}
}
}
println builder.toPrettyString()
Appreciate your time and advice. Thank you.

Answer 1

Pass a list to the builder
You don't need to iterate through the list, you can pass a list to the builder,
using JsonBuilder's implicit call() method.
def builder = new JsonBuilder()
builder {
students builder( studentList )
}
public Object call( List list )
A list of elements as arguments to the JSON builder creates a root JSON array
See the JsonBuilder Groovydoc page for details of the various call()
methods.
Example code
In this example I've fixed up your map, and introduced a small Student class, to
simplify the code.
import groovy.json.JsonBuilder
class Student { int id; String name; String email }
studentList = [
new Student( id:1, name:'John', email:'john#google.com' ),
new Student( id:2, name:'Peter', email:'peter#google.com' ),
new Student( id:3, name:'James', email:'james#google.com' )
]
def builder = new JsonBuilder()
builder {
students builder( studentList )
}
println builder.toPrettyString()
Resulting JSON
{
"students": [
{
"id": 1,
"email": "john#google.com",
"name": "John"
},
{
"id": 2,
"email": "peter#google.com",
"name": "Peter"
},
{
"id": 3,
"email": "james#google.com",
"name": "James"
}
]
}

Answer 2

I have solved it with ff code.
def students = []
def builder = new JsonBuilder()
for (Map student: studentList) {
builder {
id student.id
name student.name
contact {
email student.email
}
}
students.add(builder.toString())
}
def jsonSlurper = new JsonSlurper()
def items = jsonSlurper.parseText(students.toString())
def json = new JsonBuilder()
json "students": items
println json.toPrettyString()