My index.gson, show.gson are getting ignored with Grails 3.3.3 using JsonViews 1.2.7

Question

I am struggling with getting JSON API, and rendering of json for domain classes. I am using Grails v3.3.3 and JsonViews 1.2.7

If I expose a domain class by using @Resource annotation this automatically generates a controller and 'default' json output.

However I want some control over what's happening, so I have a another domain class (Customer, and Site in my demo app, where Customer hasMany Sites).

I do not use the @Resource annotation in either of these domain classes.

I manually create two controllers called CustomerRestController and SiteRestController by hand - and use the UrlMappings to expose the URI. (one using the '(resources: controller)' form and the other with declared explicit controller and actions:

class UrlMappings {

    static mappings = {

        "/api/customers"(resources:"customerRest")

        //or try to declare with explicit mappings
        "/api/sites" (controller: "siteRest", action: "index")
        "/api/sites/$id" (controller: "siteRest", action: "show", view: "show")

        "/$controller/$action?/$id?(.$format)?"{
            constraints {
                // apply constraints here
            }
        }

        "/"(view:"/index")
        "500"(view:'/error')
        "404"(view:'/notFound')
    }
}

So lets look first at what happens for SiteRestController (with simple debug println to show it's being called in the console). I have used the GORM data service model and just defined an interface in services and let Grails auto build the serviceImpl and then inject this into the controller. I have declared the response format to be [json]

@CompileStatic
class SiteRestController extends RestfulController {

    static responseFormats = ['json']

    SiteService siteService

    SiteRestController() {
        super (Site)
        println "siteRest default constructor controller created"
    }


    def index (Integer max)/*(@PathVariable String manufacturerName)*/ {
        println ("site.index: invoked index action on customer restful controller ")
        respond siteService.list([:]), model:[siteCount: siteService.count()]

    }


    def show(Long id) {
        println "site.show: show on SiteRestController called with $id"
        respond siteService.get(id)
    }


}

I have manually created /views/site/_site.gson, index.gson and show.gson

//_site.gson
import model.Site
println "_site template called "  //added to check that template is being called 

model {
    Site site
}

json jsonapi.render (site)

to show that view is being ignored I've edited the show.gson as follows

import model.Site

model {
    Site site
}

json g.render ([name:"will"])

and the index.gson view as

import model.Site

model {
    List<Site> siteList
    Long siteCount
}
println "index.gson more data"
json {
    name  "hello william"
}

So when I fire up the app and invoke the '/api/sites' url I get this. Which is just a standard rendering and doesn't use the _site.gson - and ignores my index.gson

[
    {
        "id": 1,
        "name": "headoffice",
        "customer": {
            "id": 1
        }
    }
]

And if I call '/api/sites/1' i get the following (this has clearly invoked the the _sites.gson template, but my 'show.gson' was modified to not use template and this is clearly being ignored)

_site template called 
{
    "data": {
        "type": "site",
        "id": "1",
        "attributes": {
            "name": "headoffice"
        },
        "relationships": {
            "customer": {
                "links": {
                    "self": "/customer/show/1"
                },
                "data": {
                    "type": "customer",
                    "id": "1"
                }
            }
        }
    },
    "links": {
        "self": "/site/show/1"
    }
}

I also tried to do a deep rendering from customers view template like this

import model.Customer


model {
    Customer customer
}

json jsonapi.render (customer, [deep:true, jsonApiObject:true])

which ignores my sites details on deep rendering when query /api/customers/1. Notice the site just shows the default id and doesn't seem to call the _site.gson:

{
    "jsonapi": {
        "version": "1.0"
    },
    "data": {
        "type": "customer",
        "id": "1",
        "attributes": {
            "name": "hsbc"
        },
        "relationships": {
            "sites": {
                "data": [
                    {
                        "type": "site",
                        "id": "1"
                    }
                ]
            }
        }
    },
    "links": {
        "self": "/customer/show/1"
    }
}

So I'm not understanding what's going one here. Grails has its own internal generated defaults and is ignoring the views etc that I have provided and doesn't seem to be doing the deep rendering when requested to do so.

Would anyone advise what why my views/templates are not being called as expected?