import grails.rest.*

@Resource(uri='/books')
class Book {

    String title

    static constraints = {
        title blank:false
    }
}

def init = { servletContext ->
    new Book(title:"The Stand").save()
    new Book(title:"The Shining").save()
}

<?xml version="1.0" encoding="UTF-8"?>
<book id="1">
    <title>The Stand</title>
</book>

{"id":1,"title":"The Stand"}

import grails.rest.*

@Resource(uri='/books', formats=['json', 'xml'])
class Book {
    ...
}

grails.mime.types = [
    ...
    json:          ['application/json', 'text/json'],
    ...
    xml:           ['text/xml', 'application/xml']
]

$ curl -i -H "Accept: application/json" localhost:8080/books/1
{"id":1,"title":"The Stand"}

$ curl -i -X POST -H "Content-Type: application/json" -d '{"title":"Along Came A Spider"}' localhost:8080/books
HTTP/1.1 201 Created
Server: Apache-Coyote/1.1
...

$ curl -i -X PUT -H "Content-Type: application/json" -d '{"title":"Along Came A Spider"}' localhost:8080/books/1
HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
...

$ curl -i -X DELETE localhost:8080/books/1
HTTP/1.1 204 No Content
Server: Apache-Coyote/1.1
...

import grails.rest.*

@Resource(uri='/books', readOnly=true)
class Book {
    ...
}

"/books"(resources:"book")

"/books"(resources:"book") {
    "/publisher"(controller:"publisher", method:"GET")
}

<g:link resource="${book}">My Link</g:link>

<form action="/book/2" method="post">
         <input type="hidden" name="_method" value="DELETE"/>
</form>

class BookController extends RestfulController<Book> {
    static responseFormats = ['json', 'xml']
    BookController() {
        super(Book)
    }
}

"/authors"(resources:'author') {
    "/books"(resources:'book')
}

class BookController extends RestfulController {
    static responseFormats = ['json', 'xml']
    BookController() {
        super(Book)
    }

    @Override
    protected Book queryForResource(Serializable id) {
        Book.where {
            id == id && author.id == params.authorId
        }.find()
    }

}

$ grails create-controller book

import grails.gorm.transactions.*
import static org.springframework.http.HttpStatus.*
import static org.springframework.http.HttpMethod.*

@Transactional(readOnly = true)
class BookController {
    ...
}

$ grails generate-controller <<Domain Class Name>>

implementation 'io.micronaut:micronaut-http-client'

$ grails create-restapi my-api

$ grails create-domain-class my.api.Book
$ ./gradlew runCommand -Pargs="generate-all my.api.Book"

implementation 'org.grails.plugins:views-json:1.0.0' // or whatever is the latest version

buildscript {
    ...
    dependencies {
        ...
        classpath "org.grails.plugins:views-gradle:1.0.0"
    }
}

...
apply plugin: "org.grails.grails-web"
apply plugin: "org.grails.plugins.views-json"

json.person {
    name "bob"
}

{"person":{"name":"bob"}}

json(1,2,3) == "[1,2,3]"
json { name "Bob" } == '{"name":"Bob"}'
json([1,2,3]) { n it } == '[{"n":1},{"n":2},{"n":3}]'

model {
    Person person
}
json {
    name person.name
    age person.age
}

model {
    Family family
}
json {
    name family.father.name
    age family.father.age
    oldestChild g.render(template:"person", model:[person: family.children.max { Person p -> p.age } ])
    children g.render(template:"person", collection: family.children, var:'person')
}

model {
    Family family
}
json {
    name family.father.name
    age family.father.age
    oldestChild tmpl.person( family.children.max { Person p -> p.age } ] )
    children tmpl.person( family.children )
}

class Book {
    String title
}

model {
    Book book
}

json g.render(book)

{id:1, title:"The Stand"}

json g.render(book, [includes:['title']])

json g.render(book) {
    pages 1000
}

def show(Long id) {
    respond Book.get(id)
}

@Transactional
def save(Book book) {
    if (book.hasErrors()) {
        transactionStatus.setRollbackOnly()
        respond book.errors
    }
    else {
        // valid object
    }
}

package myapp
import grails.rest.render.*
import grails.web.mime.MimeType

class BookXmlRenderer extends AbstractRenderer<Book> {
    BookXmlRenderer() {
        super(Book, [MimeType.XML,MimeType.TEXT_XML] as MimeType[])
    }

    void render(Book object, RenderContext context) {
        context.contentType = MimeType.XML.name

        def xml = new groovy.xml.MarkupBuilder(context.writer)
        xml.book(id: object.id, title:object.title)
    }
}

beans = {
    bookRenderer(myapp.BookXmlRenderer)
}

<book id="1" title="The Stand"/>

def show(Book book) {
    respond book
}

<%@page contentType="application/xml"%>
<book id="${book.id}" title="${book.title}"/>

{
    "_links": {
        "self": { "href": "/orders" },
        "next": { "href": "/orders?page=2" },
        "find": {
            "href": "/orders{?id}",
            "templated": true
        },
        "admin": [{
            "href": "/admins/2",
            "title": "Fred"
        }, {
            "href": "/admins/5",
            "title": "Kate"
        }]
    },
    "currentlyProcessing": 14,
    "shippedToday": 20,
    "_embedded": {
        "order": [{
            "_links": {
                "self": { "href": "/orders/123" },
                "basket": { "href": "/baskets/98712" },
                "customer": { "href": "/customers/7809" }
            },
            "total": 30.00,
            "currency": "USD",
            "status": "shipped"
        }, {
            "_links": {
                "self": { "href": "/orders/124" },
                "basket": { "href": "/baskets/97213" },
                "customer": { "href": "/customers/12369" }
            },
            "total": 20.00,
            "currency": "USD",
            "status": "processing"
        }]
    }
}

<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom">

 <title>Example Feed</title>
 <link href="http://example.org/"/>
 <updated>2003-12-13T18:30:02Z</updated>
 <author>
   <name>John Doe</name>
 </author>
 <id>urn:uuid:60a76c80-d399-11d9-b93C-0003939e0af6</id>

 <entry>
   <title>Atom-Powered Robots Run Amok</title>
   <link href="http://example.org/2003/12/13/atom03"/>
   <id>urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a</id>
   <updated>2003-12-13T18:30:02Z</updated>
   <summary>Some text.</summary>
 </entry>

</feed>

import grails.rest.render.atom.*
beans = {
    halBookRenderer(AtomRenderer, rest.test.Book)
    halBookListRenderer(AtomCollectionRenderer, rest.test.Book)
}

$ curl -i -H "Accept: application/json"  -H "Content-Type: application/json" -X POST -d "" http://127.0.0.1:8080/books

HTTP/1.1 422 Unprocessable Entity
Server: Apache-Coyote/1.1
Content-Type: application/json;charset=ISO-8859-1

{
  "errors": [
    {
      "object": "rest.test.Book",
      "field": "title",
      "rejected-value": null,
      "message": "Property [title] of class [class rest.test.Book] cannot be null"
    }
  ]
}

beans = {
    vndJsonErrorRenderer(grails.rest.render.errors.VndErrorJsonRenderer)
    // for Vnd.Error XML format
    vndXmlErrorRenderer(grails.rest.render.errors.VndErrorXmlRenderer)
}

$ curl -i -H "Accept: application/vnd.error+json,application/json" -H "Content-Type: application/json" -X POST -d "" http://127.0.0.1:8080/books
HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
Content-Type: application/vnd.error+json;charset=ISO-8859-1

[
    {
        "logref": "book.nullable,
        "message": "Property [title] of class [class rest.test.Book] cannot be null",
        "_links": {
            "resource": {
                "href": "https://127.0.0.1:8080/rest-test/books"
            }
        }
    }
]

<?xml version="1.0" encoding="UTF-8"?>
<book>
    <title>The Stand</title>
    <authorName>Stephen King</authorName>
</book>

class BookController {

    def createBook() {
        def book = new Book()
        book.properties = request

        // ...
    }
}

class BookController {
    def createBook(BookCommand book) {

        // ...
    }
}

class BookCommand {
    String title
    String authorName
}

<?xml version="1.0" encoding="UTF-8"?>
<book id="42">
    <title>Walden</title>
    <authorName>Henry David Thoreau</authorName>
</book>

class BookController {
    def updateBook(Book book) {
        // The book will have been retrieved from the database and updated
        // by doing something like this:
        //
        // book == Book.get('42')
        // if(book != null) {
        //    book.properties = request
        // }
        //
        // the code above represents what the framework will
        // have done. There is no need to write that code.

        // ...

    }
}

package org.grails.databinding.bindingsource

import grails.web.mime.MimeType
import grails.databinding.DataBindingSource

/**
 * A factory for DataBindingSource instances
 *
 * @since 2.3
 * @see DataBindingSourceRegistry
 * @see DataBindingSource
 *
 */
interface DataBindingSourceCreator {

    /**
     * `return All of the {`link MimeType} supported by this helper
     */
    MimeType[] getMimeTypes()

    /**
     * Creates a DataBindingSource suitable for binding bindingSource to bindingTarget
     *
     * @param mimeType a mime type
     * @param bindingTarget the target of the data binding
     * @param bindingSource the value being bound
     * @return a DataBindingSource
     */
    DataBindingSource createDataBindingSource(MimeType mimeType, Object bindingTarget, Object bindingSource)
}

package com.demo.myapp.databinding

import grails.web.mime.MimeType
import grails.databinding.DataBindingSource
import org...databinding.SimpleMapDataBindingSource
import org...databinding.bindingsource.AbstractRequestBodyDataBindingSourceCreator

/**
 * A custom DataBindingSourceCreator capable of parsing key value pairs out of
 * a request body containing a comma separated list of key:value pairs like:
 *
 * name:Herman,age:99,town:STL
 *
 */
class MyCustomDataBindingSourceCreator extends AbstractRequestBodyDataBindingSourceCreator {

    @Override
    public MimeType[] getMimeTypes() {
        [new MimeType('text/custom+demo+csv')] as MimeType[]
    }

    @Override
    protected DataBindingSource createBindingSource(InputStream inputStream) {
        def map = [:]

        def reader = new InputStreamReader(inputStream)

        // this is an obviously naive parser and is intended
        // for demonstration purposes only.

        reader.eachLine { line ->
            def keyValuePairs = line.split(',')
            keyValuePairs.each { keyValuePair ->
                if(keyValuePair?.trim()) {
                    def keyValuePieces = keyValuePair.split(':')
                    def key = keyValuePieces[0].trim()
                    def value = keyValuePieces[1].trim()
                    map<<key>> = value
                }
            }
        }

        // create and return a DataBindingSource which contains the parsed data
        new SimpleMapDataBindingSource(map)
    }
}

beans = {

    myCustomCreator com.demo.myapp.databinding.MyCustomDataBindingSourceCreator

    // ...
}