Parent-Child Relationship in JSON using PlayFramework - json

Question

I need to give my Angular JS application a JSON which represents Parent-Child Relationship of to tables.
Parent(Group):
+----+---------------+-------------+----------------+
| id | external_code | supplier_id | notes |
+----+---------------+-------------+----------------+
| 19 | asdfas | 3 | sadfa |
| 23 | 454 | 1 | groupa1 |
| 24 | sadfas221 | 2 | asfd |
| 25 | dsafas | 2 | NULL |
| 21 | 4545 | 1 | asdfasf |
+----+---------------+-------------+----------------+
Child(GroupItems):
+----------+---------+--------+
| group_id | item_id | status |
+----------+---------+--------+
| 19 | 1 | 0 |
| 19 | 2 | 0 |
| 19 | 3 | 0 |
| 25 | 2 | 0 |
+----------+---------+--------+
My desired JSON should look like this:
[
{"groupId":"19",
"notes":"sadfa",
"extenalCode":"asdfas",
"supplierId":"2",
"itemCount":3
"items":[{"itemId": "1","status":"Created", "weight":23},
{"itemId": "2","status":"Created", "weight":23}
{"itemId": "3","status":"Created", "weight":23}
]
},
....
]
The question is how to insert and bind child items with parent representing JSON semantics using MySQL and PlayFramework2.0(Slick)?

Answer 1

roughly something like this:
val items =
GroupItems.join(Items).on(_.itemId === _.id).run // <- query fetching items with group_ids
.groupBy(_._1.groupId).toMap
.mapValues(_._2) // <- mapping Map values to only items
// render groups to json and add a field items with the items (I may be wrong about Play's json api names)
val json = Group.run.map(g => Json.toJson(g) ++ JsObject("items" -> Json.toJson(items(g.id))))