How to render JSON on client-side from Google App Engine Entity

Question

I would much appreciate some help on rendering a JSON object on client-side from a Google App Engine entity.

Here is all of my relevant code:

def render_str(template, **params):
   t = jinja_env.get_template(template)
   return t.render(params)

class BlogHandler(webapp2.RequestHandler):
   def write(self, *a, **kw):
      self.response.out.write(*a, **kw)

   def render_str(self, template, **params):
      params['user'] = self.user
      return render_str(template, **params)

   def render(self, template, **kw):
      self.write(self.render_str(template, **kw))

class Post(ndb.Model):
   subject = ndb.TextProperty(required = True)
   created = ndb.DateTimeProperty(auto_now_add = True)
   startdate = ndb.DateTimeProperty()
   enddate = ndb.DateTimeProperty()

class PostPage(BlogHandler):
    def get(self, post_id):
    key = ndb.Key('Post', int(post_id), parent=blog_key())
    post = key.get()
    postdict = post.to_dict()
    postdict['startdate'] = postdict['startdate'].isoformat()
    self.render("permalink.html", postdict = postdict)

In my script tag on the template page, I include

<script>
var jsonobject = JSON.parse({{ postdict['startdate']}});
var jsonobject1 = new Date(jsonobject);
</script>

Am I on the right track here? I would like to ultimately use the datetime object on the client-side for some Jquery functions.

Any help in pointing me in the right direction would be much appreciated.

what language are you writing in on the app engine side? and have you dumped the object on the web browser side? console.log(...) the playload? — saturnism, Oct 30 '15 at 22:25
Thanks a lot for reply. I'm using python on app engine side. I have not dumped the object on the web browser side. Could you advise me on how to do this? — JK140, Oct 31 '15 at 23:43

score 1 · Accepted Answer · answered Oct 30 '15 at 23:14

1

There are a number of problems with your code. First of all, once you convert post to a dictionary postdict, you can't reference the elements with the dot notation. You have to use a dictionary reference postdict['startdate'] to reference the startdate element.

Next, I use the isoformat() function when storing a date in JSON format:

postdict['startdate'] = postdict['startdate'].isoformat()

This makes it easier to convert to a Javascript Date object:

<script>
var jsonobject = JSON.parse({{ postdict.jsonobject}});
jsonobject[0].y = new Date(jsonobject[0].y);
</script>

answered Oct 30 '15 at 23:14

Brent Washburne

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Thanks so much for the reply. I have the following code now: `postdict = post.to_dict()` `x = postdict['startdate'].isoformat()` `y = [ {'y':x} ]` `jsonobject = json.dumps(y)` `postict['jsonobject'] = jsonobject` And in my script tag for this template, I have: `var jsonobject = JSON.parse( {{ postdict['jsonobject'] }} );` `jsonobject[0].y = new Date(jsonobject[0].y);` However, when I reference the variable jsonobject[0].y in a jQuery function, I get an error in the console that jsonobject is undefined and JSON.parse requires at least 1 parameter. – JK140 Oct 31 '15 at 23:35
How are you rendering your template? `template.render(postdict)`? – Brent Washburne Nov 01 '15 at 02:27
I use the following functions: `def write(self, *a, **kw): self.response.out.write(*a, **kw)`, `def render_str(self, template, **params): return render_str(template, **params)` and `def render(self, template, **kw): self.write(self.render_str(template, **kw))` – JK140 Nov 01 '15 at 03:11
Please update your question with all the code, including the call with `postdict`. – Brent Washburne Nov 01 '15 at 16:10
Thanks I've included all the code now. I very much appreciate your help. I'm new to programming and I'm having a hard time understanding how to get the datetime property for one my entities on the client-side so I can use it in jQuery functions. – JK140 Nov 01 '15 at 18:06

How to render JSON on client-side from Google App Engine Entity

1 Answers1