Groovy JSONBuilder issues - json

Question

I'm trying to use JsonBuilder with Groovy to dynamically generate JSON. I want to create a JSON block like:
{
"type": {
"__type": "urn",
"value": "myCustomValue1"
},
"urn": {
"__type": "urn",
"value": "myCustomValue2"
},
"date": {
"epoch": 1265662800000,
"str": "2010-02-08T21:00:00Z"
},
"metadata": [{
"ratings": [{
"rating": "NR",
"scheme": "eirin",
"_type": {
"__type": "urn",
"value": "myCustomValue3"
}
}],
"creators": [Jim, Bob, Joe]
}]
}
I've written:
def addUrn(parent, type, urnVal) {
parent."$type" {
__type "urn"
"value" urnVal
}
}
String getEpisode(String myCustomVal1, String myCustomVal2, String myCustomVal3) {
def builder = new groovy.json.JsonBuilder()
def root = builder {
addUrn(builder, "type", myCustomVal1)
addUrn(builder, "urn", "some:urn:$myCustomVal2")
"date" {
epoch 1265662800000
str "2010-02-08T21:00:00Z"
}
"metadata" ({
ratings ({
rating "G"
scheme "eirin"
addUrn(builder, "_type", "$myCustomVal3")
})
creators "Jim", "Bob", "Joe"
})
}
return root.toString();
}
But I've run into the following issues:
Whenever I call addUrn, nothing is returned in the string. Am I misunderstanding how to use methods in Groovy?
None of the values are encapsulated in double (or single) quotes in the returned string.
Anytime I use a {, I get a '_getEpisode_closure2_closure2#(insert hex)' in the returned value.
Is there something wrong with my syntax? Or can someone point me to some example/tutorial that uses methods and/or examples beyond simple values (e.g. nested values within arrays).
NOTE: This is a watered down example, but I tried to maintain the complexity around the areas that were giving me issues.

Answer 1

You have to use delegate in addUrn method instead of
passing the builder on which you are working.
It is because you are doing a toSting() or toPrettyString() on root instead of builder.
Solved if #2 is followed.
Sample:
def builder = new groovy.json.JsonBuilder()
def root = builder {
name "Devin"
data {
type "Test"
note "Dummy"
}
addUrn(delegate, "gender", "male")
addUrn(delegate, "zip", "43230")
}
def addUrn(parent, type, urnVal) {
parent."$type" {
__type "urn"
"value" urnVal
}
}
println builder.toPrettyString()
Output:-
{
"name": "Devin",
"data": {
"type": "Test",
"note": "Dummy"
},
"gender": {
"__type": "urn",
"value": "male"
},
"zip": {
"__type": "urn",
"value": "43230"
}
}