CODEWITHSUNDEEP
pythongoogle-app-enginetypeerror
Trần Trung
Trần Trung

Reputation: 181

TypeError: bad operand type for unary -: 'type'

Good day!

I am using google app engine with python code and a problem occurred

the helloworld.py file:

import os
import urllib

import jinja2
import webapp2
import datetime

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

JINJA_ENVIRONMENT = jinja2.Environment(
loader=jinja2.FileSystemLoader(os.path.dirname(__file__)),
extensions=['jinja2.ext.autoescape'])

class MainPage(webapp2.RequestHandler):

  def get(self):

    user = users.get_current_user()

    if user:
      template_values = {
    'nickname' : user.nickname(),
      }

      template = JINJA_ENVIRONMENT.get_template('index.html')
      self.response.write(template.render(template_values))

    else:
      self.redirect(users.create_login_url(self.request.uri))

class Tutorial6(webapp2.RequestHandler):

  def get(self):
    numbers = []
    for i in range(10):
    numbers.append(i)

    template_values = {
      'numbers': numbers
    }

    template = JINJA_ENVIRONMENT.get_template('/templates/tutorial6.html')
    self.response.write(template.render(template_values))

class Tutorial7(webapp2.RequestHandler):

  def get(self):

  if users.get_current_user():
    url = users.create_logout_url(self.request.uri)
    url_linktext = 'Logout'

  else:
    url = users.create_login_url(self.request.uri)
    url_linktext = 'Login'

  cats_query = Cat.query().order(-Cat.date_of_birth)

  cats = cats_query.fetch(10)
  template_values = {
    'cats': cats,
    'url': url,
    'url_linktext': url_linktext,
  }

  template = JINJA_ENVIRONMENT.get_template('/templates/tutorial7.html')
  self.response.write(template.render(template_values))

  def post(self):
    user = users.get_current_user()

    if user:
      cat = Cat()
      cat.owner = user
      cat.name = self.request.get('name')
      cat.description = self.request.get('description')
      day = self.request.get('day')
      month = self.request.get('month')
      year = self.request.get('year')
      cat.date_of_birth = datetime.date(year=int(year), month=int(month), day=int(day))

      cat.put()
      self.redirect('/tutorial7')

    else:
      self.redirect(users.create_login_url(self.request.uri))

class Cat(ndb.Model):
  owner = ndb.UserProperty()
  name = ndb.StringProperty()
  date_of_birth = ndb.DateProperty
  description = ndb.StringProperty(indexed=False)

application = webapp2.WSGIApplication([
    ('/', MainPage),
    ('/tutorial6', Tutorial6),
    ('/tutorial7', Tutorial7),
   ], debug=True)

and when I tested it on local server, it gave this error message:

File "/home/RMITVNNET/s3408675/Desktop/.HDrive/s3372661-s3408675/helloworld.py", line 58, in get
cats_query = Cat.query().order(-Cat.date_of_birth)
TypeError: bad operand type for unary -: 'type'

I don't know what's wrong although the code looks fine. Any ideas how to fix it?

Upvotes: 1

Views: 7871

Answers (1)

Tim Hoffman
Tim Hoffman

Reputation: 12986

Have a look at your Cat class.

The date_of_birth property is not defined correctly, no (). This explains the error as the unary operator won't work with the class, it needs an instance of the property.

So rather than date_of_birth = ndb.DateProperty It should look like date_of_birth = ndb.DateProperty()

Upvotes: 4

Related Questions