I want to define multiple endpoints that render different templates, without writing out each one. The endpoints are all similar, one looks like:
#app.route('/dashboard/')
def dashboard():
return render_template('endpoints/dashboard.html')
I tried defining a function in a for loop for each endpoint name, but the problem is that the name of the function stays the same and Flask raises an error about that.
routes = ['dashboard', 'messages', 'profile', 'misc']
for route in routes:
#app.route('/' + route + '/')
def route():
return render_template('endpoints/' + route + '.html')
How can I create these views without repeating myself?
You don't want to do this. Instead, use a variable in the route to capture the template name, try to render the template, and return a 404 error if the template doesn't exist.
from flask import render_template, abort
from jinja2 import TemplateNotFound
#app.route('/<page>/')
def render_page(page):
try:
return render_template('endpoints/{}.html'.format(page))
except TemplateNotFound:
abort(404)
Alternatively, and less preferably, you can use the same function name as long as you provide Flask with unique endpoint names. The default name is the name of the function, which is why Flask complains.
for name in routes:
#app.route('/', endpoint=name)
def page():
return render_template('endpoints/{}.html'.format(name))
Related
I am running into a problem trying to redirect in Flask using the following:
#views.route('/dash_monitoring/<path:url>')
#login_required
def monitoring_page(url):
return redirect("/home/dash_monitoring/{}".format(url))
The url in <path:url> is in the format https://somesite.com/detail/?id=2102603 but when I try to print it in the function, it prints https://somesite.com/detail only without the id part,so it obviously redirects to /home/dash_monitoring/https://somesite.com/detail instead of /home/dash_monitoring/https://somesite.com/detail/?id=2102603.
What should I do so it keeps the id part and redirects to the right url?
You can use request.url and imply string manipulation:
#views.route('/dash_monitoring/<path:url>')
#login_required
def monitoring_page(url):
parsed_path = request.url.split('/dash_monitoring/')[1]
#return the parsed path
return redirect("/home/dash_monitoring/{}".format(parsed_path))
Alternatively, you can iterate through request.args for creating query string and construct path with args
#views.route('/dash_monitoring/<path:url>')
#login_required
def monitoring_page(url):
query_string = ''
for arg,value in request.args.items():
query_string+=f"{arg}={value}&"
query_string=query_string[:-1] # to remove & at the end
path=f"{path}?{query_string}"
#return the parsed path
return redirect(f"/home/dash_monitoring/{path}")
I hope this helps :)
This has an easy solution, we use the url_for function:
from flask import Flask, redirect, url_for
app = Flask(__name__)
#app.route('/<name>')
def index(name):
return f"Hello {name}!"
#app.route('/admin')
def admin():
return redirect(url_for('index',name = 'John'))
if __name__ == '__main__':
app.run(debug = True)
In my code we firs import redirect and url_for.
We create 2 routes index and admin.
In index route we output a simple response with the named passed to the url. So if we get example.com/John it will output Hello John!.
In admin route we redirect the user to index route because it's not the admin (This is a simple example that can you can model with what you want). The index route needs a name so we pass inside the url_for function some context so it can desplay the name.
I'm trying to add another view to my Flask app. My app/views.py looks like this:
from flask import render_template
from app import app
from helpfulFunctions import *
def getRankingList():
allPlayers = main()
return allPlayers
def displayLimitedNumberOfPlayers(limit):
allPlayers = main()
allPlayers[0] = limitPlayers(allPlayers[0], limit)
allPlayers[1] = limitPlayers(allPlayers[1], limit)
return allPlayers
#app.route("/")
#app.route("/index")
def index():
rankingList = getRankingList()
return render_template('index.html', title='Home', rankingList = rankingList)
#app.route("/top100")
def top100():
rankingList = displayLimitedNumberOfPlayers(100)
return render_template('top100.html', rankingList = rankingList)
if __name__ == '__main__':
app.run(debug=True)
I've tried to mimic how the Miguel Grinberg tutorial defines routes for / and for /index. I've created a view called top100.html in my templates folder, where the "index.html" file also lives. However, when I try to hit localhost:5000/top100.html, I get:
Not Found
The requested URL was not found on the server. If you entered the URL manually please check your spelling and try again.
So it seems like Flask doesn't think that URL has a view associated with it...but I'm not sure why.
Any idea?
Thanks for the help,
bclayman
There is no view top100.html in your code.You can do either of these
localhost:5000/top100
OR
change #app.route("/top100") to #app.route("/top100.html")
The route (or url) is specified in the #app.route() definition, so you should visit localhost:5000/top100.
The render_template top100.html is only referenced internally within Flask to specify the template used. Really, this page could be named anything and does not have to be named in any similar way to the route...it just has to match the template file used to build the page served at that url.
I've been trying to understand how to generate dynamic Flask URLs. I've read the docs and several example, but can't figure out why this code doesn't work:
path = 'foo'
#app.route('/<path:path>', methods=['POST'])
def index(path=None):
# do some stuff...
return flask.render_template('index.html', path=path)
I'd expect my index.html template to be served to /foo, but it is not. I get a build error. What am I missing?
If I use a fixed path, like /bar, everything works without issue.
#app.route('/bar', methods=['POST'])
You've got the long and short of it already. All you need to do is decorate your view functions using the /<var> syntax (or the /<converter:var> syntax where appropriate).
from flask import Flask, render_template
app = Flask(__name__)
#app.route('/')
def index():
return render_template('index.html')
#app.route('/<word>', defaults={'word': 'bird'})
def word_up(word):
return render_template('whatstheword.html', word=word)
#app.route('/files/<path:path>')
def serve_file(path):
return send_from_directory(app.config['UPLOAD_DIR'], path, as_attachment=True)
if __name__ == '__main__':
app.debug = True
app.run(port=9017)
When Flask pulls a variable out of a URL for a dynamic route like you're trying to use, it'll be a unicode string in Python by default. If you create the variable with the <int:var> or <float:var> converters, it'll be converted to the appropriate type in the app space for you.
The <path:blah> converter will match on a string that contains slashes (/), so you can pass /blah/dee/blah and the path variable in your view function will contain that string. Without using the path converter, flask would try and dispatch your request to a view function registered on the route /blah/dee/blah, because the plain <var> is delineated by the next / in the uri.
So looking at my little app, the /files/<path:path> route would serve whatever file it could find that matched the path sent up by the user on the request. I pulled this example from the docs here.
Also, dig that you can specify defaults for your variable URLs via a keyword arg to the route() decorator.
If you want, you can even access the underlying url_map that Werkzeug builds based on how you specify your view functions and routes in your app space. For more stuff to chew on, check out the api docs on URL registrations.
You can use add_url_rule():
def index(path=None):
return render_template('index.html', path=path)
path = '/foo'
app.add_url_rule(path, 'index', index)
You also might want to look at blueprint objects if you end up doing this alot.
The Flask documentation shows:
add_url_rule(*args, **kwargs)
Connects a URL rule. Works exactly like the route() decorator.
If a view_func is provided it will be registered with the endpoint.
endpoint – the endpoint for the registered URL rule. Flask itself assumes the name of the view function as endpoint
What exactly is meant by an "endpoint"?
How Flask Routing Works
The entire idea of Flask (and the underlying Werkzeug library) is to map URL paths to some logic that you will run (typically, the "view function"). Your basic view is defined like this:
#app.route('/greeting/<name>')
def give_greeting(name):
return 'Hello, {0}!'.format(name)
Note that the function you referred to (add_url_rule) achieves the same goal, just without using the decorator notation. Therefore, the following is the same:
# No "route" decorator here. We will add routing using a different method below.
def give_greeting(name):
return 'Hello, {0}!'.format(name)
app.add_url_rule('/greeting/<name>', 'give_greeting', give_greeting)
Let's say your website is located at 'www.example.org' and uses the above view. The user enters the following URL into their browser:
http://www.example.org/greeting/Mark
The job of Flask is to take this URL, figure out what the user wants to do, and pass it on to one of your many python functions for handling. It takes the path:
/greeting/Mark
...and matches it to the list of routes. In our case, we defined this path to go to the give_greeting function.
However, while this is the typical way that you might go about creating a view, it actually abstracts some extra info from you. Behind the scenes, Flask did not make the leap directly from URL to the view function that should handle this request. It does not simply say...
URL (http://www.example.org/greeting/Mark) should be handled by View Function (the function "give_greeting")
Actually, it there is another step, where it maps the URL to an endpoint:
URL (http://www.example.org/greeting/Mark) should be handled by Endpoint "give_greeting".
Requests to Endpoint "give_greeting" should be handled by View Function "give_greeting"
Basically, the "endpoint" is an identifier that is used in determining what logical unit of your code should handle the request. Normally, an endpoint is just the name of a view function. However, you can actually change the endpoint, as is done in the following example.
#app.route('/greeting/<name>', endpoint='say_hello')
def give_greeting(name):
return 'Hello, {0}!'.format(name)
Now, when Flask routes the request, the logic looks like this:
URL (http://www.example.org/greeting/Mark) should be handled by Endpoint "say_hello".
Endpoint "say_hello" should be handled by View Function "give_greeting"
How You Use the Endpoint
The endpoint is commonly used for the "reverse lookup". For example, in one view of your Flask application, you want to reference another view (perhaps when you are linking from one area of the site to another). Rather than hard-code the URL, you can use url_for(). Assume the following
#app.route('/')
def index():
print url_for('give_greeting', name='Mark') # This will print '/greeting/Mark'
#app.route('/greeting/<name>')
def give_greeting(name):
return 'Hello, {0}!'.format(name)
This is advantageous, as now we can change the URLs of our application without needing to change the line where we reference that resource.
Why not just always use the name of the view function?
One question that might come up is the following: "Why do we need this extra layer?" Why map a path to an endpoint, then an endpoint to a view function? Why not just skip that middle step?
The reason is because it is more powerful this way. For example, Flask Blueprints allow you to split your application into various parts. I might have all of my admin-side resources in a blueprint called "admin", and all of my user-level resources in an endpoint called "user".
Blueprints allow you to separate these into namespaces. For example...
main.py:
from flask import Flask, Blueprint
from admin import admin
from user import user
app = Flask(__name__)
app.register_blueprint(admin, url_prefix='admin')
app.register_blueprint(user, url_prefix='user')
admin.py:
admin = Blueprint('admin', __name__)
#admin.route('/greeting')
def greeting():
return 'Hello, administrative user!'
user.py:
user = Blueprint('user', __name__)
#user.route('/greeting')
def greeting():
return 'Hello, lowly normal user!'
Note that in both blueprints, the '/greeting' route is a function called "greeting". If I wanted to refer to the admin "greeting" function, I couldn't just say "greeting" because there is also a user "greeting" function. Endpoints allow for a sort of namespacing by having you specify the name of the blueprint as part of the endpoint. So, I could do the following...
print url_for('admin.greeting') # Prints '/admin/greeting'
print url_for('user.greeting') # Prints '/user/greeting'
Endpoint is the name used to reverse-lookup the url rules with url_for and it defaults to the name of the view function.
Small example:
from flask import Flask, url_for
app = Flask(__name__)
# We can use url_for('foo_view') for reverse-lookups in templates or view functions
#app.route('/foo')
def foo_view():
pass
# We now specify the custom endpoint named 'bufar'. url_for('bar_view') will fail!
#app.route('/bar', endpoint='bufar')
def bar_view():
pass
with app.test_request_context('/'):
print url_for('foo_view')
print url_for('bufar')
# url_for('bar_view') will raise werkzeug.routing.BuildError
print url_for('bar_view')
If you have same class name and want to map with multiple routes, then specify the endpoint, so that framework will differentiate between two:
class ClassName(Resource):
def get(self):
if request.endpoint!='hello':
return {"data": "Hello"}
elif:
return {"data" : "World"}
api.add_resource(ClassName, '/rout1', endpoint = "world")
api.add_resource(ClassName, '/rout2', endpoint="hello")
#app.route('/') #Endpoint
def a_function(): #View function
return 'view'
Inside Flask, every endpoint with its request methods mapped to a view function. When you use app.route decorator you are actually adding a URL rule.
Flask provides a url_for function to generate URLs to handlers based on the URL pattern. But this would imply that the handler functions must have unique names across the entire application. Is that correct?
Example
Module A has a handler index:
#app.route('/')
def index(): pass
And Module B has another handler index:
#app.route('/anotherindex')
def index(): pass
How to distinguish the handlers called index when building URLs?
url_for('index')
I don't know how you could do with all the views routed by the same module.
What I usually do is separate my views in different modules (like you did with module A and B), and register them as blueprints, after that, when using the url_for() function, you can prefix the view name with your blueprint name and then avoid conflicts and potential problems.
Here is an example:
main_views.py:
from flask import Blueprint
main = Blueprint('main', __name__)
#main.route('/')
def index():
pass
admin_views.py:
from flask import Blueprint
admin = Blueprint('admin', __name__)
#admin.route('/admin')
def index():
pass
application.py:
from flask import Flask
from main_views import main
from admin_views import admin
app = Flask('my_application')
app.register_blueprint(main)
app.register_blueprint(admin)
Now, to access the 2 index views and still distinguish one from the other, just use url_for('main.index') or url_for('admin.index')
EDIT:
Just one more useful details about routing using blueprints, when registering the blueprint, you can pass a url_prefix argument, that will apply to every view within this blueprint.
For example, given the following code:
admin_views.py
from flask import Blueprint
admin = Blueprint('admin', __name__)
#admin.route('/')
def index():
pass
#admin.route('/logout')
def logout():
pass
application.py:
from flask import Flask
from admin_views import admin
app = Flask('my_application')
app.register_blueprint(admin, url_prefix='/admin')
The 2 views would be available at the URL /admin/ and /admin/logout