访问Google App Engine数据存储区中实体的数字ID

Question

I've taken a look at this topic , on accessing id from datastore. Now I tried doing something like post.key().id() but it does not return the Numeric ID that I want.

How does one access the numeric ID of an entity in google datastore. I am using GAE 1.8 wiht Python 2.7. I believe a lot has changed from the time of the question that I just showed you.

This is all an attempt to make a permalink for my entity called post , which is a blog post.

Here is the code:

# coding=utf-8
from google.appengine.ext import db


class BlogPost(db.Model):
    title = db.StringProperty(required=True)
    content = db.TextProperty(required=True)
    created_at = db.DateTimeProperty(auto_now_add=True)

    def url(self):
        return '/blog/%s' % self.key().id()

Any help regarding this would be greatly appreciated.

Answer 1

What are you expecting this is the method to get the numeric id.

If you get None then it means you have created the entity using a string for the id.

You could try

key().id_or_name() Returns the name or numeric ID of the data entity, whichever it has, or None if the entity has neither a name nor a numeric ID.

If you get None from id_or_name() it means the entity has yet to be put()

Answer 2

When you create an entity, you specify an ancestor key, and one of either a string name, or a numeric id.

If you create it with a string, there is no numeric id.

You probably want name(), or if you're not sure id_or_name()

Here are the docs: https://developers.google.com/appengine/docs/python/datastore/keyclass#Key_id_or_name