HTML Page Loads, but shows up blank

I'm working on a project in Python, and I have part of the project working (where the user submits a post). I'm trying to make it so that when the user submits their entry, they get redirected to another page, which shows all the things they've posted. When I test this, I get redirected to the new page I made, but the page is blank. Here is my code:

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

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

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

class Entry(db.Model):
    subject = db.StringProperty(required=True)
    entry = db.TextProperty(required=True)
    created = db.DateTimeProperty(auto_now_add = True)

class MainPage(Handler):
    def render_front(self, subject="", entry="", error=""):
        blog = db.GqlQuery("SELECT * FROM Entry ORDER BY created DESC LIMIT 10")
        self.render("entry.html", subject=subject, entry=entry, error=error, blog=blog)

    def get(self):
        self.render_front()

    def post(self):
        subject = self.request.get("subject")
        entry = self.request.get("entry")

        if subject and entry:
            e = Entry(subject = subject, entry=entry)
            e.put()
            self.redirect("/BlogPost")

        else:
            error = "To post a new entry, you must add both, a subject and your post"
            self.render_front(subject, entry, error)

class BlogPost(Handler):
    def get(self):
        self.render("blogfront.html")


app = webapp2.WSGIApplication([('/', MainPage), ('/BlogPost', BlogPost)], debug = True)

This is just a piece of my code (I believe the error lies somewhere along those lines since my front page is working).

This is my blogfront.html:

<!DOCTYPE html>

<html>
   <head>
    <title>Blog </title>
   </head>

   <body>
    {% for entry in blog %}
    <div class="entry">
        <div class="entry-subject">{{entry.subject}}</div>
        <label>{{entry.created}}</label>
        <hr>
        <pre class="entry-body">{{entry.entry}}</pre>
    </div>
    {% endfor %}
   </body>
</html>

entry.html is loading while blogfront.html is not. I'm not sure where I'm going wrong with this. I would appreciate any help. Thanks in advance.

Solution

Going by your comments to questioners the issue is that while you define blog in the render_front() method, it's a local variable so it vanishes when the method returns. Try retrieving the data again in your BlogPost() method and pass that as the blog argument to self.render(). Without any blog data the template will indeed render as empty.

So your updated method might read:

class BlogPost(Handler):
    def get(self):
        blog = db.GqlQuery("SELECT * FROM Entry ORDER BY created DESC LIMIT 10")
        self.render("blogfront.html", blog=blog)

assuming that you want to see the same data you display in MainPage(), but you may well want something else.