Grails 3.1 JSON-Views, rendering a Category Tree

Question

I'm using Graisl 3.1.1, rest-api profile. I'm trying to build a Category Tree but I haven some problems rendering the categories in JSON-Views.

I'm using json templates, one for the parent and another for the child. Basically I want to generate a json for angular something like this:

These is my code.

Any help?

//domain

class Category {
  ObjectId id /* MongoDB */
  static hasMany = [categories: Category]
  String name
  ...

//controller

def directory(){
   def categories = Category.findAllByCategoriesIsNotNull([sort: 'name', order: 'asc'])
   respond categories
}

//directory.gson

import com.example.Category
model {
    Iterable<Category> categoryList
}
json {
  categories g.render(template: 'parent', collection: categoryList ?: [], var: 'category')
}

//_parent.gson

import com.example.Category
model {
  Category category
}
json {
  id   category.id.toString()
  name category.name
  categories g.render(template: "category/child", collection: category.categories ?: [], var: 'child')
}

The problem is the categories line above, I'm not sure what is the problem or my mistake.

//_child.gson

import com.example.Category
model {
  Category child
}
json {
  name child.name
}

Answer 1

I'm reasonably confident you are encountering the same fresh bug (fixed in grails-views@1.0.4) that I encountered a couple weeks ago, #9720:

it would appear that the relative path isn't recognized for g.render and the fully qualified path is required even when the template is located in the same directory as the calling gson file.

Instead of:

categories g.render(template: "category/child", collection: category.categories ?: [], var: 'child')

prepend a slash to the template:

categories g.render(template: "/category/child", collection: category.categories ?: [], var: 'child')

You may also need to change:

categories g.render(template: 'parent', collection: categoryList ?: [], var: 'category')

to:

categories g.render(template: '/category/parent', collection: categoryList ?: [], var: 'category')

Answer 2

I usually use in controller

import grails.converters.JSON

and then

render result as JSON