Datastore Tutorial

[Ben Woodhead]

Hey Everybody, 

I am new to python and the datastore so I am in the perfect place to document my questions to make it easier for the next person. I am going to avoid all the display stuff and just talk about getting data in and out of the datastore. In this example we are going to develop a backend database for books. 

What is the ancestry stuff and how should I really organize my data? Should we put everything into books and magazines?

Books -> book 1, book 2

Magazines -> mag 1, mag 2

What does that look like in python or java?

class Books(db.Model):

    pass

class Book(Books):

    name = db.StringProperty(required=True)

    created = db.DateProperty(auto_now_add=True)

How do I put that into the datastore?

book = Books(name="test book")

book.put()

How do you get the key of that book?

book.key()

How do you find all the books?

books = db.GqlQuery("SELECT * FROM Book WHERE ANCESTER IS Books ORDER BY created DESC LIMIT 10")

How do I loop through the results?

for book in books:

  print book.key() ????

  print book.name

Thanks, 

Ben

ps In the example they use the method below to create a key.. What does it really mean or do?

def guestbook_key(guestbook_name=None):
  """Constructs a Datastore key for a Guestbook entity with guestbook_name."""
  return db.Key.from_path('Guestbook', guestbook_name or 'default_guestbook')

[Kaan Soral]

Someone has already done these before you :) !

https://developers.google.com/appengine/docs/python/datastore/overview
better: https://developers.google.com/appengine/docs/python/ndb/overview