ObjectGraphBuilder from and to a file - groovy

Question

How can I make ObjectGraphBuilder to build my class instance from an string? I mean if I have
String myString = """invoices{
invoice(date: new Date(106,1,2)){
item(count:5){
product(name:'ULC', dollar:1499)
}
item(count:1){
product(name:'Visual Editor', dollar:499)
}
}
invoice(date: new Date(106,1,2)){
item(count:4) {
product(name:'Visual Editor', dollar:499)
}
}
"""
how can turn this string (myString) into an instance of the invoice class (I assume I have to use ObjectGraphBuilder but how?)
Given an instance of the class invoice ( with all of its nested properties), how can I turn that instance into an string like myString?
I also want to be able serialize and deserialize from a text file too but I assume it is the same as the string.

Answer 1

You can work with GroovyShell to evaluate the string and delegate the methods called in the script to an ObjectGraphBuilder. I repeated the "invoices" method. If this is unacceptable, take a look at Going to Mars with Domain-Specific Languages, by Guillaume Laforge, where he teaches how to customize the compiler.
I also created an Invoices class, because of the way ObjectGraphBuilder works. If this will be dynamic for you, take a look at its resolvers.
import groovy.transform.ToString as TS
#TS class Invoices { List<Invoice> invoices=[] }
#TS class Invoice { List<Item> items=[]; Date date }
#TS class Item { Integer count; Product product }
#TS class Product { String name; Integer dollar; Vendor vendor }
#TS class Vendor { Integer id }
String myString = """
invoices {
invoice(date: new Date(106,1,2)){
item(count:5){
product(name:'ULC', dollar:1499)
}
item(count:1){
product(name:'Visual Editor', dollar:499)
}
}
invoice(date: new Date(106,1,2)){
item(count:4) {
product(name:'Visual Editor', dollar:499)
}
}
}
"""
invoicesParser = { Closure c ->
new ObjectGraphBuilder().invoices c
}
binding = new Binding( [invoices: invoicesParser] )
invoices = new GroovyShell(binding).evaluate myString
assert invoices.invoices.size() == 2
Update: as for your second question, i'm not aware, and neither could found, any way back to the object graph builder representation. You can roll your own, but i think you will be better if you try something like json. Does your use case permit you to do so?
use( groovy.json.JsonOutput ) {
assert invoices.toJson().prettyPrint() == """{
"invoices": [
{
"date": "2006-02-02T02:00:00+0000",
"items": [
{
"product": {
"vendor": null,
"dollar": 1499,
"name": "ULC"
},
"count": 5
},
{
"product": {
"vendor": null,
"dollar": 499,
"name": "Visual Editor"
},
"count": 1
}
]
},
{
"date": "2006-02-02T02:00:00+0000",
"items": [
{
"product": {
"vendor": null,
"dollar": 499,
"name": "Visual Editor"
},
"count": 4
}
]
}
]
}"""
}