Working with Python Dash and have it working from local host, but when attempt to deploy to my python app server, I have issues.
When I keep the app as just Flask it works with this code:
from flask import Flask
import dash
app = Flask(__name__)
#app.route("/")
def hello():
return "Hello World!"
When I try to pass the server to the Dash instance (when according to Dash docs is acceptable, I receive the error). Here is the code
from flask import Flask
import dash
server = Flask(__name__)
app = dash.Dash(__name__, server=server)
#app.route("/")
def hello():
return "Hello World!"
I receiving the error:
AttributeError: 'Dash' object has no attribute 'route'
The docs don't say what you think they do. app is the Dash instance, not the Flask one - that is available via the server variable, so you can call route on that.
#server.route("/")
def hello():
return "Hello World!"
As Daniel Roseman said, you must use server.route instead of app.route.
However, Dash registers itself to serve the path /, overwriting your route.
Other paths not used by Dash work as expected, e.g.:
#server.route('/hello-world')
def hello():
return "Hello World!"
Related
I have a simple flask app inside a class structure so that the flask server can be initiated by calling the call_flaskapp function :
|--folder structure
|---------flask_file.py
|---------main.py
File name is flask_file
from flask import Flask
class flask_app:
def call_flaskapp(self):
app = Flask(__name__)
#app.route('/')
def hello_world():
return 'Hello World'
app.run(debug =True)
Here the main python file from where I am calling the function:
from flask_file import flask_app
fa = flask_app()
fa.call_flaskapp()
The server is up and running but whenever I am opening the URL I am getting a 404 error.
I might be doing a silly mistake . Please let me know
Thanks
I'm attempting to deploy a simple web app, and I'm using command line waitress-serve --call command. But every time, the command immediately returns 1. Malformed application 'name_of_project_here'.
Here's my flask web app in python:
from flask import Flask, render_template
app = Flask(__name__)
#app.route('/')
def index():
return render_template('base.html')
if __name__ == '__main__':
app.run(debug = True)
and the command I run is just
waitress-serve --call "name_of_project"
I did try looking through the documentation, and I found where the error occurs, but couldn't find an explanation of why it's occurring. What does malformed application mean?
Minimal working example:
If you put code in file main.py
from flask import Flask
def create_app():
app = Flask(__name__)
#app.route('/')
def index():
return "Hello World!"
return app
if __name__ == '__main__':
app = create_app()
app.run()
then you can run it as
waitress-serve --call "main:create_app"
So "name_of_project" has to be "filename:function_name" which creates Flask() instance.
It can't be any text. And if you forget : then you may see "Malformed application"
when defining your appname and the function that initialize your app with : dont put them into quotes('')
I am trying to host a flask server from my windows computer so I can access it from external devices
I am using Flask/Python and have already tried a few things but can't get it to work
Tried running it on 0.0.0.0, port 33, 5000, etc. but I still can't access it this way
from flask import Flask, request, abort
app = Flask(__name__)
if __name__ == '__main__':
app.run(host='0.0.0.0', port=33)
When I then run the file I get:
Running on http://0.0.0.0:33/ (Press CTRL+C to quit)
But it isn't even running there, nor on any other way I can access it
I expect to be able to access my flask application and send requests to it by using my public IP address
What can I do here to make it work?
You have missed an important line in your code:
After the line
app = Flask(__name__)
You have to write the line:
#app.route('/')
We use the route() decorator to tell Flask what URL should trigger our function.
And then define a function that will tell what task to be performed in the web app hosted in the respective address.
The function might look something like this:
def hello_world():
return 'Hello, World!'
The complete code then will look like:
from flask import Flask
app = Flask(__name__)
#app.route('/')
def hello_world():
return 'Hello, World!'
if __name__ == '__main__':
app.run(host='0.0.0.0', port=33)
Hope this helps.
I'm working through RealPython and I'm having trouble with the flask dynamic route.
Everything seemed to work until the dynamic route. Now if I try to enter a "search query" (i.e. localhost:5000/test/hi) the page is not found. localhost:5000 still works fine.
# ---- Flask Hello World ---- #
# import the Flask class from the flask module
from flask import Flask
# create the application object
app = Flask(__name__)
# use decorators to link the function to a url
#app.route("/")
#app.route("/hello")
# define the view using a function, which returns a string
def hello_world():
return "Hello, World!"
# start the development server using the run() method
if __name__ == "__main__":
app.run()
# dynamic route
#app.route("/test/<search_query>")
def search(search_query):
return search_query
I can't see that other people using RealPython have had an issue with the same code, so I'm not sure what I'm doing wrong.
The reason why this is not working is because flask never learns that you have another route other / and /hello because your program gets stuck on app.run().
If you wanted to add this, all you need to do would be to add the new route before calling app.run() like so:
# ---- Flask Hello World ---- #
# import the Flask class from the flask module
from flask import Flask
# create the application object
app = Flask(__name__)
# use decorators to link the function to a url
#app.route("/")
#app.route("/hello")
# define the view using a function, which returns a string
def hello_world():
return "Hello, World!"
# dynamic route
#app.route("/test/<search_query>")
def search(search_query):
return search_query
# start the development server using the run() method
if __name__ == "__main__":
app.run(host="0.0.0.0", debug=True, port=5000)
Now this will work.
Note: You don't need to change the run configurations inside of app.run. You can just use app.run() without any arguments and your app will run fine on your local machine.
Try using the entire URL instead of just the IP address.
Consider the following minimal working flask app:
from flask import Flask
app = Flask(__name__)
#app.route("/")
def hello():
return "I am /"
#app.route("/api")
def api():
return "I am /api"
if __name__ == "__main__":
app.run()
This happily works. But when I try to make a GET request with the "requests" module from the hello route to the api route - I never get a response in the browser when trying to access http://127.0.0.1:5000/
from flask import Flask
import requests
app = Flask(__name__)
#app.route("/")
def hello():
r = requests.get("http://127.0.0.1:5000/api")
return "I am /" # This never happens :(
#app.route("/api")
def api():
return "I am /api"
if __name__ == "__main__":
app.run()
So my questions are: Why does this happen and how can I fix this?
You are running your WSGI app with the Flask test server, which by default uses a single thread to handle requests. So when your one request thread tries to call back into the same server, it is still busy trying to handle that one request.
You'll need to enable threading:
if __name__ == "__main__":
app.run(threaded=True)
or use a more advanced WSGI server; see Deployment Options.