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passing arguments to API created by flask in python

I am a complete newbie to API and python. actually, after getting disappointed to find a free host supporting plumber in R I decided to try it by python. The simple problem is that I have a simple function which takes two numeric arguments and using a given CSV file do some calculations and returns a number (I have simply made this in R by the plumber in localhost). now for a test in python have written below code:
from flask import Flask
app = Flask(__name__)
#app.route("/")
def hello():
return "hello world!"
if __name__ == '__main__':
app.run(debug=True)
well, this correctly works. but when I try to make a function to take arguments like this:
from flask import Flask
app = Flask(__name__)
#app.route("/")
def hello(a):
return a + 2
if __name__ == '__main__':
app.run(debug=True)
I get this page which says I have not passed the arguments.
my main question is that how I can pass the arguments? (in API created by R plumber, for example, I call it like: localhost/5000/?a=2 )
my another question is, could be this kind of API host and request in something like Heroku?

From Flask documentation:
You can add variable sections to a URL by marking sections with <variable_name>. Your function then receives the <variable_name> as a keyword argument. Optionally, you can use a converter to specify the type of the argument like <converter:variable_name>.
So in your case that would be:
#app.route("/<int:a>")
def hello(a):
return a + 2
Other option would be to use request data.

You need to include the parameter "a" in the decorator #app.route:
#app.route('/<int:a>')
def hello(a):
return a + 2

You can also use it like that, pass name as parameter !
#app.route('/helloworld/<Name>')
def helloworld(Name):
print Name
another implementation would be like that, go through the python-flask documentation !
#app.route("/<int:a>")
def hello(a):
return a + 2

Mock flask.request in python nosetests

I'm writing test cases for code that is called via a route under Flask. I don't want to test the code by setting up a test app and calling a URL that hits the route, I want to call the function directly. To make this work I need to mock flask.request and I can't seem to manage it. Google / stackoverflow searches lead to a lot of answers that show how to set up a test application which again is not what I want to do.
The code would look something like this.
somefile.py
-----------
from flask import request
def method_called_from_route():
data = request.values
# do something with data here
test_somefile.py
----------------
import unittest
import somefile
class SomefileTestCase(unittest.TestCase):
#patch('somefile.request')
def test_method_called_from_route(self, mock_request):
# want to mock the request.values here
I'm having two issues.
(1) Patching the request as I've sketched out above does not work. I get an error similar to "AttributeError: 'Blueprint' object has no attribute 'somefile'"
(2) I don't know how to exactly mock the request object if I could patch it. It doesn't really have a return_value since it isn't a function.
Again I can't find any examples on how to do this so I felt a new question was acceptable.

Try this
test_somefile.py
import unittest
import somefile
import mock
class SomefileTestCase(unittest.TestCase):
def test_method_called_from_route(self):
m = mock.MagicMock()
m.values = "MyData"
with mock.patch("somefile.request", m):
somefile.method_called_from_route()
unittest.main()
somefile.py
from flask import request
def method_called_from_route():
data = request.values
assert(data == "MyData")
This is going to mock the entire request object.
If you want to mock only request.values while keeping all others intact, this would not work.

A few years after the question was asked, but this is how I solved this with python 3.9 (other proposed solutions stopped working with python 3.8 see here). I'm using pytest and pytest-mock, but the idea should be the same across testing frameworks, as long as you are using the native unittest.mock.patch in some capacity (pytest-mock essentially just wraps these methods in an easier to use api). Unfortunately, it does require that you set up a test app, however, you do not need to go through the process of using test_client, and can just invoke the function directly.
This can be easily handled by using the Application Factory Design Pattern, and injecting application config. Then, just use the created app's .test_request_context as a context manager to mock out the request object. using .test_request_context as a context manager, gives everything called within the context access to the request object. Here's an example below.
import pytest
from app import create_app
#pytest.fixture
def request_context():
"""create the app and return the request context as a fixture
so that this process does not need to be repeated in each test
"""
app = create_app('module.with.TestingConfig')
return app.test_request_context
def test_something_that_requires_global_request_object(mocker, request_context):
"""do the test thing"""
with request_context():
# mocker.patch is just pytest-mock's way of using unittest.mock.patch
mock_request = mocker.patch('path.to.where.request.is.used')
# make your mocks and stubs
mock_request.headers = {'content-type': 'application/json'}
mock_request.get_json.return_value = {'some': 'json'}
# now you can do whatever you need, using mock_request, and you do not
# need to remain within the request_context context manager
run_the_function()
mock_request.get_json.assert_called_once()
assert 1 == 1
# etc.
pytest is great because it allows you to easily setup fixtures for your tests as described above, but you could do essentially the same thing with UnitTest's setUp instance methods. Happy to provide an example for the Application Factory design pattern, or more context, if necessary!

with help of Gabrielbertouinataa on this article: https://medium.com/#vladbezden/how-to-mock-flask-request-object-in-python-fdbc249de504:
code:
def print_request_data():
print(flask.request.data)
test:
flask_app = flask.Flask('test_flask_app')
with flask_app.test_request_context() as mock_context:
mock_context.request.data = "request_data"
mock_context.request.path = "request_path"
print_request_data()

Here is an example of how I dealt with it:
test_common.py module
import pytest
import flask
def test_user_name(mocker):
# GIVEN: user is provided in the request.headers
given_user_name = "Some_User"
request_mock = mocker.patch.object(flask, "request")
request_mock.headers.get.return_value = given_user_name
# WHEN: request.header.get method is called
result = common.user_name()
# THEN: user name should be returned
request_mock.headers.get.assert_called_once_with("USERNAME", "Invalid User")
assert result == given_user_name
common.py module
import flask
def user_name():
return flask.request.headers.get("USERNAME", "Invalid User")

What you're trying to do is counterproductive. Following the RFC 2616 a request is:
A request message from a client to a server includes, within the first line of that message, the method to be applied to the resource, the identifier of the resource, and the protocol version in use.
Mocking the Flask request you need to rebuild its structure, what certainly, you will not to want to do!
The best approach should be use something like Flask-Testing or use some recipes like this, and then, test your method.

Match an arbitrary path, or the empty string, without adding multiple Flask route decorators

I want to capture all urls beginning with the prefix /stuff, so that the following examples match: /users, /users/, and /users/604511/edit. Currently I write multiple rules to match everything. Is there a way to write one rule to match what I want?
#blueprint.route('/users')
#blueprint.route('/users/')
#blueprint.route('/users/<path:path>')
def users(path=None):
return str(path)

It's reasonable to assign multiple rules to the same endpoint. That's the most straightforward solution.
If you want one rule, you can write a custom converter to capture either the empty string or arbitrary data beginning with a slash.
from flask import Flask
from werkzeug.routing import BaseConverter
class WildcardConverter(BaseConverter):
regex = r'(|/.*?)'
weight = 200
app = Flask(__name__)
app.url_map.converters['wildcard'] = WildcardConverter
#app.route('/users<wildcard:path>')
def users(path):
return path
c = app.test_client()
print(c.get('/users').data) # b''
print(c.get('/users-no-prefix').data) # (404 NOT FOUND)
print(c.get('/users/').data) # b'/'
print(c.get('/users/400617/edit').data) # b'/400617/edit'
If you actually want to match anything prefixed with /users, for example /users-no-slash/test, change the rule to be more permissive: regex = r'.*?'.

Pyramid TranslationString not working on json renderer

In a test I am doing in a pyramid application, I am trying to send a translatable text via JSON, but the translation is not working. At the beginning of the file I am importing the translation string function:
from pyramid.i18n import TranslationString as _
Then consider the following code:
#view_config(route_name='transtest', renderer='json')
def transtest_view(request):
return { 'myvar': _('temp-test', default='Temporary test', domain='myapp') }
But what I get is:
{"myvar": "temp-test"}
Note that if I change the renderer to a test template I did as follows:
#view_config(route_name='transtest', renderer='../templates/transtest.pt')
...
then the text gets translated correctly (note that I already initialized the catalogs, updated them, compiled them, etc.)
This made me think that the TranslationString class does not work right in a 'json' renderer? If so, how can I make to send a translatable string via JSON?
Thanks in advance

You need to explicitly translate your message string, using get_localizer() and Localizer.translate():
from pyramid.i18n import get_localizer
#view_config(route_name='transtest', renderer='json')
def transtest_view(request):
message = _('temp-test', default='Temporary test', domain='myapp')
return {'myvar': get_localizer(request).translate(message)}
Normally, templates take care of these steps for you, but for JSON you'll need to do so yourself.
You probably want to define a TranslationStringFactory for your project, and reuse that to produce your message strings. Add the following to your project:
from pyramid.i18n import TranslationStringFactory
myapp_domain = TranslationStringFactory(domain='myapp')
then use:
from my.project import myapp_domain as _
# ....
message = _('temp-test', default='Temporary test')

Get list of all routes defined in the Flask app

I have a complex Flask-based web app. There are lots of separate files with view functions. Their URLs are defined with the #app.route('/...') decorator. Is there a way to get a list of all the routes that have been declared throughout my app? Perhaps there is some method I can call on the app object?

All the routes for an application are stored on app.url_map which is an instance of werkzeug.routing.Map. You can iterate over the Rule instances by using the iter_rules method:
from flask import Flask, url_for
app = Flask(__name__)
def has_no_empty_params(rule):
defaults = rule.defaults if rule.defaults is not None else ()
arguments = rule.arguments if rule.arguments is not None else ()
return len(defaults) >= len(arguments)
#app.route("/site-map")
def site_map():
links = []
for rule in app.url_map.iter_rules():
# Filter out rules we can't navigate to in a browser
# and rules that require parameters
if "GET" in rule.methods and has_no_empty_params(rule):
url = url_for(rule.endpoint, **(rule.defaults or {}))
links.append((url, rule.endpoint))
# links is now a list of url, endpoint tuples
See Display links to new webpages created for a bit more information.

I just met the same question. Those solutions above are too complex.
Just open a new shell under your project:
>>> from app import app
>>> app.url_map
The first 'app' is my project script: app.py,
another is my web's name.
(this solution is for the tiny web with a little route)

I make a helper method on my manage.py:
#manager.command
def list_routes():
import urllib
output = []
for rule in app.url_map.iter_rules():
options = {}
for arg in rule.arguments:
options[arg] = "[{0}]".format(arg)
methods = ','.join(rule.methods)
url = url_for(rule.endpoint, **options)
line = urllib.unquote("{:50s} {:20s} {}".format(rule.endpoint, methods, url))
output.append(line)
for line in sorted(output):
print line
It solves the the missing argument by building a dummy set of options. The output looks like:
CampaignView:edit HEAD,OPTIONS,GET /account/[account_id]/campaigns/[campaign_id]/edit
CampaignView:get HEAD,OPTIONS,GET /account/[account_id]/campaign/[campaign_id]
CampaignView:new HEAD,OPTIONS,GET /account/[account_id]/new
Then to run it:
python manage.py list_routes
For more on manage.py checkout: http://flask-script.readthedocs.org/en/latest/

Apparently, since version 0.11, Flask has a built-in CLI. One of the built-in commands lists the routes:
FLASK_APP='my_project.app' flask routes

Similar to Jonathan's answer I opted to do this instead. I don't see the point of using url_for as it will break if your arguments are not string e.g. float
#manager.command
def list_routes():
import urllib
output = []
for rule in app.url_map.iter_rules():
methods = ','.join(rule.methods)
line = urllib.unquote("{:50s} {:20s} {}".format(rule.endpoint, methods, rule))
output.append(line)
for line in sorted(output):
print(line)

Use cli command in Directory where your flask project is.
flask routes

Since you did not specify that it has to be run command-line, the following could easily be returned in json for a dashboard or other non-command-line interface. The result and the output really shouldn't be commingled from a design perspective anyhow. It's bad program design, even if it is a tiny program. The result below could then be used in a web application, command-line, or anything else that ingests json.
You also didn't specify that you needed to know the python function associated with each route, so this more precisely answers your original question.
I use below to add the output to a monitoring dashboard myself. If you want the available route methods (GET, POST, PUT, etc.), you would need to combine it with other answers above.
Rule's repr() takes care of converting the required arguments in the route.
def list_routes():
routes = []
for rule in app.url_map.iter_rules():
routes.append('%s' % rule)
return routes
The same thing using a list comprehension:
def list_routes():
return ['%s' % rule for rule in app.url_map.iter_rules()]
Sample output:
{
"routes": [
"/endpoint1",
"/nested/service/endpoint2",
"/favicon.ico",
"/static/<path:filename>"
]
}

If you need to access the view functions themselves, then instead of app.url_map, use app.view_functions.
Example script:
from flask import Flask
app = Flask(__name__)
#app.route('/foo/bar')
def route1():
pass
#app.route('/qux/baz')
def route2():
pass
for name, func in app.view_functions.items():
print(name)
print(func)
print()
Output from running the script above:
static
<bound method _PackageBoundObject.send_static_file of <Flask '__main__'>>
route1
<function route1 at 0x128f1b9d8>
route2
<function route2 at 0x128f1ba60>
(Note the inclusion of the "static" route, which is created automatically by Flask.)

You can view all the Routes via flask shell by running the following commands after exporting or setting FLASK_APP environment variable.
flask shell
app.url_map

inside your flask app do:
flask shell
>>> app.url_map
Map([<Rule '/' (OPTIONS, HEAD, GET) -> helloworld>,
<Rule '/static/<filename>' (OPTIONS, HEAD, GET) -> static>])

print(app.url_map)
That, is, if your Flask application name is 'app'.
It's an attribute of the instance of the Flask App.
See https://flask.palletsprojects.com/en/2.1.x/api/#flask.Flask.url_map