I have tried everything but it seems that you cannot get a catch all url...
- url: /.*
script: not_found.py
...to work on urls that are based on static directory paths. eg. I can type in www.foobar.com/asdas/asd/asd/asd/ad/sa/das/d and I can get a nice custom 404 page. But if I alter a static path url like www.foobar.com/mydir/mydir/mypage.html, I just get the horrible generic 404....
Error: Not Found
The requested URL /mydir/mydir/mypage.html was not found on this server.
... I would like to alter whatever catches the url in directory paths and writes the 404. This appears the only way to get a consistent custom 404 page in GAE Python.
Can anyone help? I have written my website from scratch and have a very limited knowledge of Python. Achieving a consistent custom 404 is the only thing I cannot seem to overcome.
EDIT/ADD : OK I've added the kind suggestion of #Lipis , and gone through getting started which which thankfully has given me a much better understanding of classes (I sadly can't vote it up yet). But! I am using a .py script found on the net and I think the NotFound class is interfering with the class that gives my index page, because now my index page is the 404 page specified by the Jinja! I have very little understanding of MainHandler so I may have to give up for now.
import os
from google.appengine.ext import webapp
from google.appengine.ext.webapp import util
from google.appengine.ext.webapp import template
from google.appengine.ext.webapp.util import run_wsgi_app
import jinja2
class MainHandler(webapp.RequestHandler):
def get (self, q):
if q is None:
q = 'index.html'
path = os.path.join (os.path.dirname (__file__), q)
self.response.headers ['Content-Type'] = 'text/html'
self.response.out.write (template.render (path, {}))
class NotFound(webapp.RequestHandler):
def post(self):
# you need to create the not_found.html file
# check Using Templates from Getting Started for more
jinja_environment = jinja2.Environment(
loader=jinja2.FileSystemLoader(os.path.dirname(__file__)))
template = jinja_environment.get_template('404.html')
self.response.out.write(template.render(template_values))
def main ():
application = webapp.WSGIApplication ([('/(.*html)?', MainHandler),('/.*', NotFound)],
debug=True)
util.run_wsgi_app (application)
if __name__ == '__main__':
main ()
For better understanding I'll make some modifications on the Getting Started example which I assume that you have done it and you made some experiments with it.
It's not a good idea to have the static file for all the not found pages in the app.yaml since most likely you would like to show something more dynamic and usually the - url: /.* should be handled within your app.
In this example we are going to add a new RequestHandler for all your not found pages
import jinja2
import os
# more imports
jinja_environment = jinja2.Environment(loader=jinja2.FileSystemLoader(os.path.dirname(__file__)))
class MainPage(webapp2.RequestHandler):
def get(self):
template = jinja_environment.get_template('index.html')
self.response.out.write(template.render(template_values))
class NotFound(webapp.RequestHandler):
def get(self):
# you need to create the not_found.html file
# check Using Templates from Getting Started for more
template = jinja_environment.get_template('not_found.html')
self.response.out.write(template.render(template_values))
application = webapp.WSGIApplication(
[('/', MainPage),
('/.*', NotFound)], # <-- This line is important
debug=True)
But in order to make the jinja2 templates work, follow carefully the modifications that you need to do in Using Templates section from the Getting Started.
The order in the URL mapping is very important so this catch all regular expression (/.*) should be always the last one, because otherwise all the other rules will be skipped.
If you want to catch all URLs, you will have to modify your main request handler in your file "not_found.py" by adding '/.*'.
For example, you can set the file "not_found.py" to:
from google.appengine.ext import webapp
from google.appengine.ext.webapp.util import run_wsgi_app
class MainHandler(webapp.RequestHandler):
def get(self):
self.response.out.write("Hello, MAIN!")
application = webapp.WSGIApplication(
[('/.*', MainHandler)], # <--- Add '/.*' here
debug=True)
def main():
run_wsgi_app(application)
If you navigate to www.foobar.com/asd/ad/sa/das/d or any other URL, you will see the message "Hello, MAIN!.
Hope it helps. Ask question if needed
Related
I use Jinja2 with Webapp2 on a GAE project.
I have a base RequestHandler as describe in webapp2_extras.jinja2:
import webapp2
from webapp2_extras import jinja2
def jinja2_factory(app):
"""Set configuration environment for Jinja."""
config = {my config...}
j = jinja2.Jinja2(app, config=config)
return j
class BaseHandler(webapp2.RequestHandler):
#webapp2.cached_property
def jinja2(self):
# Returns a Jinja2 renderer cached in the app registry.
return jinja2.get_jinja2(factory=jinja2_factory, app=self.app)
def render_response(self, _template, **context):
# Renders a template and writes the result to the response.
rv = self.jinja2.render_template(_template, **context)
self.response.write(rv)
And a view handler as:
class MyHandler(BaseHandler):
def get(self):
context = {'message': 'Hello, world!'}
self.render_response('my_template.html', **context)
My templates are in the default location (templates).
The app works well on dev server, and the template is correctly rendered.
But when I try to unittest MyHandler with
import unittest
import webapp2
import webstest
class MyHandlerTest(unittest.TestCase):
def setUp(self):
application = webapp2.WSGIApplication([('/', MyHandler)])
self.testapp = webtest.TestApp(application)
def test_response(self):
response = application.get_response('/')
...
application.get_response('/my-view') raise an exception: TemplateNotFound: my_template.html.
Is there something I missed? Like a jinja2 environment or template loader configuration?
Problem origin:
Jinja2 default loader searches files in a relative ./templates/ directory. When you run your GAE application on the development server this path is relative to the root of your application. But when you run your unittests this path is relative to your unittest files.
Solution:
Not really an ideal solution, but here a trick I did to solve my problem.
I updated the jinja2 factory to add a dynamic template path, set in app config:
def jinja2_factory(app):
"""Set configuration environment for Jinja."""
config = {'template_path': app.config.get('templates_path', 'templates'),}
j = jinja2.Jinja2(app, config=config)
return j
And I set an absolute path to the templates in the setUp of my unittests:
class MyHandlerTest(unittest.TestCase):
def setUp(self):
# Set template path for loader
start = os.path.dirname(__file__)
rel_path = os.path.join(start, '../../templates') # Path to my template
abs_path = os.path.realpath(rel_path)
application.config.update({'templates_path': abs_path})
Can error_handler be set for a blueprint?
#blueprint.errorhandler(404)
def page_not_found(error):
return 'This page does not exist', 404
edit:
https://github.com/mitsuhiko/flask/blob/18413ed1bf08261acf6d40f8ba65a98ae586bb29/flask/blueprints.py
you can specify an app wide and a blueprint local error_handler
You can use Blueprint.app_errorhandler method like this:
bp = Blueprint('errors', __name__)
#bp.app_errorhandler(404)
def handle_404(err):
return render_template('404.html'), 404
#bp.app_errorhandler(500)
def handle_500(err):
return render_template('500.html'), 500
errorhandler is a method inherited from Flask, not Blueprint.
If you are using Blueprint, the equivalent is app_errorhandler.
The documentation suggests the following approach:
def app_errorhandler(self, code):
"""Like :meth:`Flask.errorhandler` but for a blueprint. This
handler is used for all requests, even if outside of the blueprint.
"""
Therefore, this should work:
from flask import Blueprint, render_template
USER = Blueprint('user', __name__)
#USER.app_errorhandler(404)
def page_not_found(e):
""" Return error 404 """
return render_template('404.html'), 404
On the other hand, while the approach below did not raise any error for me, it didn't work:
from flask import Blueprint, render_template
USER = Blueprint('user', __name__)
#USER.errorhandler(404)
def page_not_found(e):
""" Return error 404 """
return render_template('404.html'), 404
add error handling at application level using the request proxy object:
from flask import request,jsonify
#app.errorhandler(404)
#app.errorhandler(405)
def _handle_api_error(ex):
if request.path.startswith('/api/'):
return jsonify(ex)
else:
return ex
flask Documentation
I too couldn't get the top rated answer to work, but here's a workaround.
You can use a catch-all at the end of your Blueprint, not sure how robust/recommended it is, but it does work. You could also add different error messages for different methods too.
#blueprint.route('/<path:path>')
def page_not_found(path):
return "Custom failure message"
Surprised others didn't mention miguelgrinberg's excellent tutorial.
https://blog.miguelgrinberg.com/post/the-flask-mega-tutorial-part-vii-error-handling
I found the sentry framework for error handling (links below). Seems overly complex. not sure of the threshold where it becomes useful.
https://flask.palletsprojects.com/en/1.1.x/errorhandling/
https://docs.sentry.io/platforms/python/guides/flask/
I combined previous excellent answers with the official docs from Flask, section 'Returning API Errors as JSON', in order to provide a more general approach.
Here is a working PoC that you can copy and paste on your registered blueprint API route handler (e.g. app/api/routes.py):
#blueprint.app_errorhandler(HTTPException)
def handle_exception(e):
"""Return JSON instead of HTML for HTTP errors."""
# start with the correct headers and status code from the error
response = e.get_response()
# replace the body with JSON
response.data = json.dumps({
"code": e.code,
"name": e.name,
"description": e.description,
})
response.content_type = "application/json"
return response
Flask doesnt support blueprint level error handlers for 404 and 500 errors. A BluePrint is a leaky abstraction. Its better to use a new WSGI App for this, if you need separate error handlers, this makes more sense.
Also i would recommend not to use flask, it uses globals all over the places, which makes your code difficult to manage if it grows bigger.
We're working on a Backbone.js application and the fact that we can start a HTTP server by typing python -m SimpleHTTPServer is brilliant.
We'd like the ability to route any URL (e.g. localhost:8000/path/to/something) to our index.html so that we can test Backbone.Router with HTML5 pushState.
What is the most painless way to accomplish that? (For the purpose of quick prototyping)
Just use the built in python functionality in BaseHTTPServer
import BaseHTTPServer
class Handler( BaseHTTPServer.BaseHTTPRequestHandler ):
def do_GET( self ):
self.send_response(200)
self.send_header( 'Content-type', 'text/html' )
self.end_headers()
self.wfile.write( open('index.html').read() )
httpd = BaseHTTPServer.HTTPServer( ('127.0.0.1', 8000), Handler )
httpd.serve_forever()
Download and install CherryPy
Create the following python script (call it always_index.py or something like that) and also replace 'c:\index.html' with the path of your actual file that you want to use
import cherrypy
class Root:
def __init__(self, content):
self.content = content
def default(self, *args):
return self.content
default.exposed = True
cherrypy.quickstart(Root(open('c:\index.html', 'r').read()))
Run python <path\to\always_index.py>
Point your browser at http://localhost:8080 and no matter what url you request, you always get the same content.
I'm new to python and Google App Engine. I'm trying to refactor this code from Nick Johnson blog to use webapp2 and python 2.7. http://blog.notdot.net/2009/10/Blogging-on-App-Engine-part-1-Static-serving
Anyways, when I run the code below I get this error.
TypeError: get() takes exactly 2 arguments (1 given)
I think it may have something to do with the path variable not being defined, but I don't know how to define it.
import webapp2
from google.appengine.ext import webapp
from google.appengine.ext import db
class StaticContent(db.Model):
body = db.BlobProperty()
content_type = db.StringProperty(required=True)
last_modified = db.DateTimeProperty(required=True, auto_now=True)
def get(path):
return StaticContent.get_by_key_name(path)
def set(path, body, content_type, **kwargs):
content = StaticContent(
key_name=path,
body=body,
content_type=content_type,
**kwargs)
content.put()
return content
class MainHandler(webapp2.RequestHandler):
def get(self, path):
content = get(path)
if not content:
self.error(404)
return
app = webapp2.WSGIApplication([('/', MainHandler)],
debug=True)
The error is raised because the get method of the MainHandler class expects a path parameter.
You should add grouping to the regex in your routing definition to pass the path parameter to the get method:
app = webapp2.WSGIApplication([('(/.*)', MainHandler)],
debug=True)
I'm using AppEngine to store some pickled python objects in my app. I want to serve these to the user directly, and I'm simply using the X-AppEngine-Blobkey header to serve the files to the user with a file.pickle.gz filename. However, when I try to extract these on my computer (Mac OS) using a simple double click, the files are turned into file.pickle.gz.cpgz.
I thought it was my browser being sneaky and extracting them, but I don't think so, since
pickle.load('file.pickle.gz')
Doesn't work, and neither does
pickle.load('file.pickle.gz.cpgz')
To store the files, I use:
blobfile = files.blobstore.create(mime_type='application/gzip')
with files.open(blobfile, 'a') as f:
gz = gzip.GzipFile(fileobj=f,mode='wb')
gz.write(my_pickled_object)
gz.close()
files.finalize(blobfile)
I think I'm not understanding the way gzips work. Can someone explain?
Are you sure file.pickle.gz.cpgz is the result of your double-clicking on the file.pickle.gz file you downloaded? Usually ".cpgz" is a different kind of archive file.
I can get the code you posted to work in a development server without significant changes. Here's the code, if it helps:
#!/usr/bin/env python
from __future__ import with_statement
import gzip
import pickle
from google.appengine.api import files
from google.appengine.api import memcache
from google.appengine.ext import blobstore
from google.appengine.ext import webapp
from google.appengine.ext.webapp import blobstore_handlers
from google.appengine.ext.webapp import util
class MainHandler(webapp.RequestHandler):
def get(self):
self.response.out.write('Hello world! make get')
class MakeFileHandler(webapp.RequestHandler):
def get(self):
data = pickle.dumps({'a':1, 'b':True, 'c':None})
blobfile = files.blobstore.create(mime_type='application/gzip')
with files.open(blobfile, 'a') as f:
gz = gzip.GzipFile(fileobj=f,mode='wb')
gz.write(data)
gz.close()
files.finalize(blobfile)
memcache.set('filekey', files.blobstore.get_blob_key(blobfile))
self.redirect('/')
class GetFileHandler(blobstore_handlers.BlobstoreDownloadHandler):
def get(self):
blobkey = memcache.get('filekey')
if blobkey:
self.send_blob(blobkey)
else:
self.response.out.write('No data key set back')
def main():
application = webapp.WSGIApplication([('/', MainHandler),
('/make', MakeFileHandler),
('/get', GetFileHandler)],
debug=True)
util.run_wsgi_app(application)
if __name__ == '__main__':
main()
Click on "make", then click on "get". A file named "get.gz" is downloaded to your ~/Downloads/ folder (at least in Chrome). Double-click on it to produce a file named "get". Then:
% python
>>> import pickle
>>> pickle.load(open('get'))
{'a': 1, 'c': None, 'b': True}