grails 3.1.1 & json views - json

Question

I've been playing around with Grails-3.1.1 and creating restful services but when I use them to generate from a collection and responding using templates I get the following error:
URI /api/buildings
Class java.lang.IllegalStateException
Message
Error rendering view: Error rendering view: Cannot write a name when a name has just been written. Write a value first!
Caused by
Cannot write a name when a name has just been written. Write a value first!
I followed the example on the json-views github page
https://github.com/grails/grails-views
My index.gson file looks like this
model {
List<Building> buildingList
}
json tmpl.building(buildingList)
And my _building.gson template file like this
model {
Building building
}
json g.render(building)
If I don't use the templates all works well but then I get too little info - I want to expand on some of the object relationships instead of just returning the id. Using a show.gson template accessing the same _building.gson file does seem to work OK. The controller in question extends from RestfulController and only implements the contructor as shown below
#Transactional(readOnly = true)
class BuildingRestController extends RestfulController {
static responseFormats = ['json', 'xml']
BuildingRestController() {
super(Building)
}
}
Any ideas what is going wrong and do others have it working?
Stack trace:
Line | Method
->> 8 | writeTo in C:\Users\Colin\code\biztool\grails-app\views\buildingRest\index.gson
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Caused by ViewRenderException: Error rendering view: Cannot write a name when a name has just been written. Write a value first!
->> 8 | writeTo in C:\Users\Colin\code\biztool\grails-app\views\buildingRest\_building.gson
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Caused by IllegalStateException: Cannot write a name when a name has just been written. Write a value first!
->> 624 | writeName in grails.plugin.json.builder.StreamingJsonBuilder$StreamingJsonDelegate
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
| 563 | call in ''
| 149 | process . . . . . . . . in grails.plugin.json.view.api.internal.JsonGrailsViewHelper
| 74 | doCall in grails.plugin.json.view.api.internal.JsonGrailsViewHelper$_render_closure1
| 689 | cloneDelegateAndGetContent in grails.plugin.json.builder.StreamingJsonBuilder$StreamingJsonDelegate
| 681 | cloneDelegateAndGetContent in ''
| 199 | call . . . . . . . . . in grails.plugin.json.builder.StreamingJsonBuilder
| 72 | render in grails.plugin.json.view.api.internal.JsonGrailsViewHelper
| 58 | render . . . . . . . . in ''
| 8 | run in _info_app_name__buildingRest__building_gson
| 32 | doWrite . . . . . . . . in grails.plugin.json.view.JsonViewTemplate
| 30 | writeTo in grails.views.AbstractWritableScript
| 280 | render . . . . . . . . in grails.plugin.json.view.api.internal.JsonGrailsViewHelper
| 30 | invokeMethod in grails.plugin.json.view.api.internal.TemplateRenderer
| 8 | run . . . . . . . . . . in _info_app_name__buildingRest_index_gson
| 32 | doWrite in grails.plugin.json.view.JsonViewTemplate
| 30 | writeTo . . . . . . . . in grails.views.AbstractWritableScript
| 64 | renderMergedOutputModel in grails.views.mvc.GenericGroovyTemplateView
| 94 | render . . . . . . . . in grails.views.mvc.renderer.DefaultViewRenderer
| 188 | internalRespond in grails.artefact.controller.RestResponder$Trait$Helper
| 62 | respond . . . . . . . . in ''
| 64 | index in grails.rest.RestfulController
| 96 | doInTransaction . . . . in grails.transaction.GrailsTransactionTemplate$2
| 93 | execute in grails.transaction.GrailsTransactionTemplate
| 80 | doFilter . . . . . . . in grails.plugin.springsecurity.rest.RestLogoutFilter
| 53 | doFilter in grails.plugin.springsecurity.web.filter.GrailsAnonymousAuthenticationFilter
| 143 | doFilter . . . . . . . in grails.plugin.springsecurity.rest.RestAuthenticationFilter
| 62 | doFilter in grails.plugin.springsecurity.web.authentication.logout.MutableLogoutFilter
| 58 | doFilter . . . . . . . in grails.plugin.springsecurity.web.SecurityRequestHolderFilter
| 35 | doFilterInternal in CorsFilter.java
| 1142 | runWorker . . . . . . . in java.util.concurrent.ThreadPoolExecutor
| 617 | run in java.util.concurrent.ThreadPoolExecutor$Worker
^ 745 | run . . . . . . . . . . in java.lang.Thread