tornado_rest_queries_books.py

class BooksHandler(BaseHandler):

    def initialize(self):
        database_url = os.environ['BOOKS_DB_CONN']
        self.session = queries.TornadoSession(uri=database_url)

    """
    GET handler for fetching numbers from database
    """
    @gen.coroutine
    def get(self):
        try:
            sql = "SELECT array_to_json(array_agg(row_to_json(json))) json FROM (SELECT bookid, title, book_info FROM books ORDER BY title) as json;"
            results = yield self.session.query(sql, {})
            data_ret = results.as_dict()
            results.free()
            print(data_ret)
            self.set_status(200)
            self.write({'message': 'All books sorted by title', 'books': data_ret['json']})
            self.finish()
        except (queries.DataError, queries.IntegrityError) as error:
            print(error)
            self.set_status(500)
            self.write({'message': 'Error getting books', 'books': [] })
            self.finish()

    """
    POST handler for adding a new book to the database
    """
    @gen.coroutine   
    def post(self):

        book_json            = self.request.body.decode('utf-8')
        if (book_json == None or book_json == ''):
            self.set_status(200)
            self.write({'message': 'Book data is missing', 'book': {}})
            self.finish()
            return

        try:
            book_json = tornado.escape.json_decode(book_json)
        except (Exception) as e:
            self.set_status(500)
            self.write({'message': 'Error: Book data is not in valid JSON format', 'book': {} })
            self.finish()
            return

        if 'title' not in book_json:
            self.set_status(200)
            self.write({'message': 'Error: book data is missing title, no book was created', 'book': {} })
            self.finish()
            return
        book_json['book_info'] = book_json.get('book_info', {})

        try:
            sql = "INSERT INTO public.books(title, book_info) VALUES (%(book_title)s, %(book_info)s) RETURNING json_build_object('title', title, 'book_info', book_info);"
            results = yield self.session.query(sql, {'book_title': book_json['title'], 'book_info': tornado.escape.json_encode(book_json['book_info'])})
            data_ret = results.as_dict()
            results.free()
            self.set_status(201)
            self.write({'message': 'Book added', 'book': data_ret['json_build_object']})
            self.finish()
        except (queries.DataError, queries.IntegrityError) as error:
            print(error)
            self.set_status(500)
            self.write({'message': 'Error: no book with that id exists', 'book': {} })
            self.finish()