CODEWITHSUNDEEP
google-app-enginepython-2.7google-cloud-datastore
Bondifrench
Bondifrench

Reputation: 1282

key.from_path equivalent to get_by_id in GAE datastore

I have the following Model in GAE's datastore:

class Blog(db.Model):
    subject = db.StringProperty(required = True)
    content = db.TextProperty(required = True)
    created = db.DateTimeProperty(auto_now_add = True)  
    last_modified = db.DateTimeProperty(auto_now = True)

I create a new post with the following class:

class NewPostHandler(Handler):
    def render_newpost(self, subject="", content="", error=""):
        self.render("newpost.html", subject=subject, content=content, error=error)

    def get(self):
        self.render_newpost()

    def post(self):
        subject = self.request.get("subject")
        content = self.request.get("content")
        if subject and content:
            a = Blog(parent = blog_key(), subject=subject, content=content)
            a.put() 
            self.redirect("/blog/%s" %str(a.key().id()))
        else:
            error = "we need both a subject and some text!"
            self.render_newpost(subject, content, error)

I use this piece of code to define a key:

def blog_key(name = 'default'):
    return db.Key.from_path('blogs', name)

My problem is when trying to render it, the following using get_by_id works:

class PermalinkHandler(Handler):
    def get(self, blog_id):
        blog = Blog.get_by_id(int(blog_id), parent=None)
    if not blog:
         self.response.write('There is no blog whose id is %s' %blog_id)
         return
        self.render("permalink.html", blog = blog)

When I try to replace blog = Blog.get_by_id(int(blog_id), parent=None) with 

k = db.Key.from_path('Blog', int(blog_id), parent=blog_key())
blog = db.get(k)

It doesn't work, any idea why? Thx

Upvotes: 0

Views: 176

Answers (1)

Tim Hoffman
Tim Hoffman

Reputation: 12986

The obvious question is are you supplying the parent in the working code.

def get(self, blog_id):
        blog = Blog.get_by_id(int(blog_id), parent=None)

Looking at your code the parent is always None, and in your post handler you are not showing us how you create blog_key

Then in your non working code you have 

k = db.Key.from_path('Blog', int(blog_id), parent=blog_key())
blog = db.get(k)

So my guess is the problem is due to inconsistent use of parent in your keys.

Upvotes: 1

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