Grails can do RESTfull easily enough, but I wanted a restful API from grails without throwing out grails scaffolding, So I decided to customize Grails’ controller template.
grails install-templates
then in [app-name]/src/templates/scaffolding/Controller.groovy
import org.springframework.dao.DataIntegrityViolationException
import grails.converters.XML
import grails.converters.JSON
class ${className}Controller {
static allowedMethods = [list:'GET',
show:'GET',
edit:['GET', 'POST'],
save:'POST',
update:['POST','PUT'],
delete:['POST','DELETE']
]
def index() {
redirect(action: "list", params: params)
}
def list() {
params.max = Math.min(params.max ? params.int('max') : 50, 200)
def list = ${className}.list(params)
def listObject = [${propertyName}List: list, ${propertyName}Total: ${className}.count()]
withFormat {
html listObject
json { render list as JSON }
xml { render listObject as XML }
}
}
def create() {
[${propertyName}: new ${className}(params)]
}
def save() {
def ${propertyName} = new ${className}(params)
if (!${propertyName}.save(flush: true)) {
withFormat {
html {render(view: "create", model: [${propertyName}: ${propertyName}])}
json {
response.status = 403
render ${propertyName}.errors as JSON
}
xml {
response.status =403
render ${propertyName}.errors as XML
}
}
return
}
flash.message = message(code: 'default.created.message', args: [message(code: '${domainClass.propertyName}.label', default: '${className}'), ${propertyName}.id])
withFormat {
html {
redirect(action: "show", id: ${propertyName}.id)
}
json {
response.status = 201
render ${propertyName} as JSON
}
xml {
response.status = 201
render ${propertyName}.id
}
}
}
def show() {
def ${propertyName} = ${className}.get(params.id)
if (!${propertyName}) {
withFormat {
html {
flash.message = message(code: 'default.not.found.message', args: [message(code: '${domainClass.propertyName}.label', default: '${className}'), params.id])
redirect(action: "list")
}
json { response.sendError(404) }
xml { response.sendError(404) }
}
return
}
def object = [${propertyName}: ${propertyName}]
withFormat {
html {object}
json { render object as JSON }
xml { render object as XML }
}
}
def edit() {
def ${propertyName} = ${className}.get(params.id)
if (!${propertyName}) {
flash.message = message(code: 'default.not.found.message', args: [message(code: '${domainClass.propertyName}.label', default: '${className}'), params.id])
redirect(action: "list")
return
}
[${propertyName}: ${propertyName}]
}
def update() {
def ${propertyName} = ${className}.get(params.id)
if (!${propertyName}) {
withFormat {
html {
flash.message = message(code: 'default.not.found.message', args: [message(code: '${domainClass.propertyName}.label', default: '${className}'), params.id])
redirect(action:"list")
}
json { response.sendError(404) }
xml { response.sendError(404) }
}
return
}
if (params.version) {
def version = params.version.toLong()
if (${propertyName}.version > version) {
${propertyName}.errors.rejectValue("version", "default.optimistic.locking.failure",
[message(code: '${domainClass.propertyName}.label', default: '${className}')] as Object[],
"Another user has updated this ${className} while you were editing")
withFormat {
html {render(view: "edit", model: [${propertyName}: ${propertyName}])}
json { response.sendError(409) }
xml { response.sendError(409) }
}
return
}
}
${propertyName}.properties = params
if (!${propertyName}.save(flush: true)) {
withFormat {
html {render(view: "edit", model: [${propertyName}: ${propertyName}])}
json {
response.status = 403
render ${propertyName}.errors as JSON
}
xml {
response.status = 403
render ${propertyName}.errors as XML
}
}
return
}
withFormat {
html {
flash.message = message(code: 'default.updated.message', args: [message(code: '${domainClass.propertyName}.label', default: '${className}'), ${propertyName}.id])
redirect(action: "show", id: ${propertyName}.id)
}
json {
response.status = 204
render ${propertyName} as JSON
}
xml {
response.status = 204
render ''
}
}
}
def delete() {
def ${propertyName} = ${className}.get(params.id)
if (!${propertyName}) {
withFormat {
html {
flash.message = message(code: 'default.not.found.message', args: [message(code: '${domainClass.propertyName}.label', default: '${className}'), params.id])
redirect(action: "list")
}
json { response.sendError(404) }
xml { response.sendError(404) }
}
return
}
try {
${propertyName}.delete(flush: true)
withFormat {
html {
flash.message = message(code: 'default.deleted.message', args: [message(code: '${domainClass.propertyName}.label', default: '${className}'), params.id])
redirect(action: "list")
}
json {
response.status = 204
render ''
}
xml {
response.status = 204
render ''
}
}
}
catch (DataIntegrityViolationException e) {
withFormat {
html {
flash.message = message(code: 'default.not.deleted.message', args: [message(code: '${domainClass.propertyName}.label', default: '${className}'), params.id])
redirect(action: "show", id: params.id)
}
json { response.sendError(500) }
xml { response.sendError(500) }
}
}
}
}
then modify your UrlMappings.groovy file to look something like this:
class UrlMappings {
static mappings = {
"/$controller/$action?/$id?"{
constraints {
// apply constraints here
}
}
name api0: "/api/$controller/$id"(parseRequest:true){
action = [GET: "show", PUT: "update", DELETE: "delete"]
constraints {
id(matches:/\d+/)
}
}
name api1: "/api/$controller"(parseRequest:true){
action = [GET: "list", POST: "save"]
}
}
}
I found the JSON Restful plugin a while after I already did most of this, so that is another way to go. Other than it having some issues in grails 2 right now it looks like a really good option, but one thing I like about my approach is that if you want to customize your API in fine detail you can do so. You can always generate individual controllers and modify them of course. Another option is registering custom marshallers. The simple example for customizing your JSON output without changing any controller code would be doing something like this in your Bootstrap.groovy
import grails.converters.JSON
class BootStrap {
def init = {servletContext ->;
JSON.registerObjectMarshaller(Person) {
def returnArray = [:]
returnArray['name'] = it.name
returnArray['addrs'] = it.addresses
return returnArray
}
...
}
...
