Develop Reference

How can I modify the property of ndb model through a webapp2 handler in python

I have a python file and an html file that interact with each other through the jinja2 environment in a manner similar to the one in this tutorial.
The following code controls the interaction between the html file and the python file:
class MainPage(webapp2.RequestHandler):
def get(self):
submission_query = Submission.query().order(-Submission.score)
submissions = submission_query.fetch(10)
template_values = {
'Submission' : Submission,
'submissions' : submissions,
}
template = JINJA_ENVIRONMENT.get_template('index.html')
self.response.write(template.render(template_values))
app = webapp2.WSGIApplication([
('/', MainPage),
('/create', CreateSubmmission),
('/voteup', VoteUp),
], debug=True)
I have a ndb model as follows:
class Submission(ndb.Model):
username = ndb.StringProperty()
placename = ndb.StringProperty()
link = ndb.StringProperty()
score = ndb.IntegerProperty()
I have an html form to create a new Submission as follows:
<form action="/create" method="post">
add a new location: <br>
your name:<div><textarea name="username" rows="2" cols="60"></textarea></div>
placename:<div><textarea name="placename" rows="2" cols="60"></textarea></div>
url:<div><textarea name="link" rows="2" cols="60"></textarea></div>
<div><input type="submit" value="Post"></div>
</form>
Using this request handler:
class CreateSubmmission(webapp2.RequestHandler):
def post(self):
submission = Submission()
submission.username = self.request.get('username')
submission.placename = self.request.get('placename')
submission.link = self.request.get('link')
submission.score = 0
submission.put()
self.redirect('/')
I have a section in my html which prints out each Submission along with a button for upvoting it:
{% for Submission in submissions %}
<p>
{{Submission.username}} posted:
<strong>{{Submission.placename}}</strong> <br>
score:{{Submission.score}}<br>
<!--Vote up button-->
<form action="/voteup?submission={{Submission}}" method="post">
<div><input type="submit" value="voteup"></div>
</form>
</p><br><br>
{% endfor %}
The upvoting is handled by the following python class:
class VoteUp(webapp2.RequestHandler):
def post(self):
submission = self.request.get('Submission')
submission_key = submission.put()
the_submission = submission_key.get()
the_submission.score +=1
the_submission.put()
self.redirect('/')
When pressing the button, the value of the respective Submission's score attribute should increase by one.
The code is implemented on the website sunlit-hook-91816.appspot.com. As can be seen on that site, pressing the upvote button generates the following error:
File "/base/data/home/apps/s~sunlit-hook-91816/1.383863233180213164/guestbook.py", line 52, in post
submission_key = submission.put()
AttributeError: 'str' object has no attribute 'put'
It appears that the VoteUp class is somehow unable to modify the value of Submission.score.
I am using the information found here but I can't figure out how to correctly apply it this problem. Can anyone tell me of a way to make the VoteUp class modify the Submission.score?

You're using the Submission object like it can be passed along between html/python code but it can't, you must add a reference in the form and dereference it back in you server.
Do this in the vote form:
<form action="/voteup?submission={{Submission.key.urlsafe()}}" method="post">
<div><input type="submit" value="voteup"></div>
</form>
We're getting the key of the submission in a format safe for http transport, so it can arrive back to the server unaltered.
Now when processing the vote, we can recreate the key and get the correct object:
class VoteUp(webapp2.RequestHandler):
def post(self):
submission = self.request.get('submission')
submission_key = ndb.Key(urlsafe=submission)
the_submission = submission_key.get()
the_submission.score +=1
the_submission.put()
self.redirect('/')
As you can see we're just recreating the key based on the formatted string we printed in the form.
Another way you could do this to make it even better is to use an extra input in the form:
<form action="/voteup" method="post">
<input name="submission" type="hidden" value="{{Submission.key.urlsafe()}}">
<div><input type="submit" value="voteup"></div>
</form>
Your code will work the same way, but I find it easier to read and maintain.

How do I get information from a form using webapp2?

I have the following scenario:
<form class=*** method="post" action=("main.py" ???)>
<input class=*** type="email" name="email">
<input class=*** type="submit" value=***>
</form>
This form is in a .html file, evidently in a different file from the python code. I wish know which ways do I have to get the information from the form and send to the python file to finally work on it (I guess is something about the action field but not sure).
OBS: I must use the webapp2 (I'm using the google server so django and other stuff do not work on it)

You can see Handling Forms with webapp2 from the Google App Engine wepapp2 tutorial.
import cgi
from google.appengine.api import users
import webapp2
MAIN_PAGE_HTML = """\
<html>
<body>
<form action="/sign" method="post">
<div><textarea name="content" rows="3" cols="60"></textarea></div>
<div><input type="submit" value="Sign Guestbook"></div>
</form>
</body>
</html>
"""
class MainPage(webapp2.RequestHandler):
def get(self):
self.response.write(MAIN_PAGE_HTML)
class Guestbook(webapp2.RequestHandler):
def post(self):
self.response.write('<html><body>You wrote:<pre>')
self.response.write(cgi.escape(self.request.get('content')))
self.response.write('</pre></body></html>')
application = webapp2.WSGIApplication([
('/', MainPage),
('/sign', Guestbook),
], debug=True)
And read through the entire tutorial for more information about Datastore and template
Using template allow you to put code html code in another file.

Flask giving error 400 on file upload

I have the following
<form action="classify_upload" method="post" id="upload-form">
<input type="file" name="imagefile" id="imagefile"/>
<input type="submit" />
</form>
And in my flask webapp I have the following rule:
#webapp.route('/upload', methods=['POST'])
def upload():
try:
imagefile = flask.request.files['imagefile']
...
except Exception as err:
...
But I am getting a error 400: bad request, which from my googling tells me Flask can not find the file under the key 'imagefile' which is the name of the input in the html. Any ideas why it is not finding it?

Turns out I need to include the enctype in the form, so the html should be
<form action="classify_upload" method="post" id="upload-form" enctype="multipart/form-data">
<input type="file" name="imagefile" id="imagefile"/>
<input type="submit" />
</form>

Bottle: Global Variable 'request' is not defined

I am creating a web based application with python where the user enters a search query and data is returned. I used bottle to provide the web framework for this. Openshift is then used to post online. It is a simple post form and the search criteria is then used in the next section using this:
#route('/')
def search():
return '''
<h1 align="center">Twitter Sentiment Analysis</h1>
<p align="center">Enter what you would like to search in the search box below</p>
<form action="/result" method="post" align="center">
Search: <input name="search" type="text" />
<input value="Search" type="submit" />
</form>
'''
#route('/result', method='POST')
def result():
search = request.forms.get('search')
return 'it worked'
When using bottle and tested it, it worked fine, but when I try to deploy it to OpenShift, I get a name error, "global variable 'request' is not defined" when in testing it worked perfectly with just bottle before deploying to openshift, does anyone know why this may be?

It seems like you haven't imported the request or route to namespace:
from bottle import get, post, request # or route
#get('/login') # or #route('/login')
def login():
return '''
<form action="/login" method="post">
Username: <input name="username" type="text" />
...
'''
#post('/login') # or #route('/login', method='POST')
def do_login():
user = request.forms.get('username')
pass = request.forms.get('password')
...

How to handle delete in Google App Engine (Python)

I'm a newbie programmer and new to Google App Engine and webapp2 etc. So this may be a very basic question.
I am creating an application to store images into BlobStore. My model stores description, blob_key, image url and date.
I am able to save everything, so that bit is okay.
But now I want to create a delete button which will not only delete an item from the datastore, but also delete the image saved in the blobstore.
I have created a DeleteHandler, and in the html I have a form, passing the key for the item I want to delete. In the DeleteHandler, I am using the posted key to delete the item from the datastore. I am also trying to use the key to use it delete the image saved in the blobstore.
So far I'm getting a 404 on the delete form post, and even if I get past that, I'm not sure if my DeleteHandler is correct to handle the functionality I am looking for.
Any help would be much appreciated..
Main.py:
import os
import urllib
import webapp2
from google.appengine.ext.webapp import template
from google.appengine.ext import blobstore
from google.appengine.ext.webapp import blobstore_handlers
from google.appengine.api import images
#Models
from google.appengine.ext import db
class ImageItem(db.Model):
description = db.StringProperty(required=True)
img_url = db.StringProperty()
blob_key = blobstore.BlobReferenceProperty()
when = db.DateTimeProperty(auto_now_add=True)
#Handlers (Views)
class MainHandler(webapp2.RequestHandler):
def get(self):
upload_url = blobstore.create_upload_url('/upload')
imgs = db.GqlQuery(
'SELECT * FROM ImageItem '
'ORDER BY when DESC')
imgs_dict = {'imgs': imgs}
self.response.out.write( template.render( 'main.html',locals() ) )
class UploadHandler(blobstore_handlers.BlobstoreUploadHandler):
def post(self):
f = self.get_uploads('file')[0] # 'file' is file upload field in the form
img =ImageItem(description=self.request.get('description'))
img.blob_key = f.key()
img.img_url = images.get_serving_url( f.key() )
img.put()
self.redirect('/')
class DeleteHandler(webapp2.RequestHandler):
def post(self):
key = self.request.get('k')
item = db.get(key)
images.delete( item.blob_key )
item.delete()
self.response.out.write(key)
#URL Routing happens here
app = webapp2.WSGIApplication([('/', MainHandler),
('/upload', UploadHandler),
('/delete', DeleteHandler)],
debug=True)
Main.html:
<form action="{{upload_url}}" method="POST" enctype="multipart/form-data">
<p>
<label for="file">Upload File</label>
<input type="file" name="file" id="file">
</p>
<p>
<label for="description">Description</label>
<input type="text" id="description" name="description">
</p>
<input type="submit" name="submit" value="Submit">
</form>
<ul>
{% for i in imgs %}
<li>
<img src="{{i.img_url}}=s400-c" alt="">
{{i.description }}
</li>
<li>{{i.when }}</li>
<li>
<form action="/delete" method="POST" enctype="multipart/form-data">
<input type="text" name="k" value="{{i.key}}" />
<input type="submit" value="delete">
</form>
</li>
{% endfor %}
</ul>

The deletes are close. Once you have a key, you can delete entities by calling db.delete(key).
For your example, this would be something like this:
class DeleteHandler(webapp2.RequestHandler):
def post(self):
key = self.request.get('k')
item = db.get(key)
blobstore.delete([item.blob_key])
db.delete(item)
self.response.out.write(key)
Your url handling in main.py is good, so it's not obvious to me why you're getting a 404. You could double-check your app.yaml file to make sure all urls are passed to main.py.
Here's a sample app.yaml handlers url section:
handlers
- url: /.*
script: main.app

Got it to work. Thanks Eric, yours was real close. I needed to use blob_key.key().
Final code is following:
class DelHandler(webapp2.RequestHandler):
def post(self):
key = self.request.get('k')
item = db.get(key)
n = item.blob_key.key()
blobstore.delete(n)
item.delete()
self.redirect('/')