CherryPy receives empty POST from emberjs RESTAdapter

Question

I am exploring the use of CherryPy as back-end and emberjs as front-end for a simple web-application that manages a list of books. Cherrypy simply serves a handlebars template upon a request for index:

import os
import cherrypy
from google.appengine.api import users
from google.appengine.ext import ndb

class Root:

    def __init__(self):
        # book REST API
        self.books = BookAPI()

    @cherrypy.expose
    def index(self):
        return open(os.path.join(template_env, 'index.hbs'))

And I use classes BooksAPI and Books to serve as RESTfull API that employs the Google data storage for storing book objects (I only store isbn now).

class BookAPI():
    exposed=True

    @cherrypy.tools.json_out()
    def GET(self, isbn=None):

        # get the current user
        user = users.get_current_user()

        if(isbn is None):

            # query all books current user
            ancestor_key = ndb.Key("Library", str(user.user_id()))
            books = Book.query_books(ancestor_key).fetch(20)

            # convert to JSON list of books
            book_list = []
            for index, b in enumerate(books):
                book_list.append({'id': index, 'isbn': b.isbn})
            result = {
                "books": book_list
            }

        return result

    def POST(self, isbn):

        # get the current user
        user = users.get_current_user()

        # create book and save in data storage
        parent_key = ndb.Key('Library', user.user_id())
        book = Book(parent=parent_key, isbn=isbn)
        book.put()

    ...

class Book(ndb.Model):

    isbn = ndb.StringProperty()

    @classmethod
    def query_books(cls, ancestor_key):
        return cls.query(ancestor=ancestor_key)

For the emberjs clientside I use the RESTAdapter:

window.Books = Ember.Application.create();
Books.ApplicationAdapter = DS.RESTAdapter.extend();

My emberjs book model is defined as follows:

Books.Book = DS.Model.extend({
  isbn: DS.attr('string'),
});

And I added the following book controllers:

Books.BookController = Ember.ObjectController.extend({
  actions: {
    removeBook: function() {
      var book = this.get('model');
      book.deleteRecord();
      book.save();
    }
  }
});

Books.BooksController = Ember.ArrayController.extend({
  actions: {
    createBook: function() {
      // get book isbn
      var isbn = this.get('newIsbn');
      if(!isbn.trim()) { return; }
      // create new book model
      var book = this.store.createRecord('book', {
        isbn: isbn,
      });
      // clear the 'new book' text field
      this.set('newIsbn', '');
      // Save model
      book.save();
    }
  }
});

And finally the following routes:

Books.Router.map(function () {
  this.resource('books', { path: '/' });
});

Books.BooksRoute = Ember.Route.extend({
  model: function() {
    return this.store.find('book');
  }
});

Adding and deleting books using the FixedAdapter worked, then I switched to the RESTAdapter.

The GET method worked. Emberjs automatically invokes the GET method and successfully obtains a list of books in JSON format that are displayed in the index.hbs template.

However, emberjs calls the POST method in a way I did not expect. It seems that ember sends an empty POST, without the isbn added as POST data. Because when I remove the isbn keyword argument from the cherrypy POST function, the function does get called. I need the isbn though, to create the book object.

I am probably forgetting something obvious here, but I cannot figure out what. Does anyone has an idea what I am forgetting or doing wrong? Thanks.

Bastiaan

Answer 1

For saving new records Ember send a json representation of the object being saved in the post body...

In your case sholud be

book:{isbn:[the isbn value]}

So there is no isbn parameter

Can you test with this on your post function

def POST(self):

    # get the current user
    user = users.get_current_user()
    cl = cherrypy.request.headers['Content-Length']
    rawbody = cherrypy.request.body.read(int(cl))
    body = simplejson.loads(rawbody)
    bookFromPost = body.book
    # create book and save in data storage
    parent_key = ndb.Key('Library', user.user_id())
    book = Book(parent=parent_key, isbn=bookFromPost.isbn)
    book.put()

You should return a 201 created HTTP code with a json representation of the book with assigned id

book:{id:[the new id],isbn:[the isbn value]}