Passing argument to class instantiated by framework? (Python Flask)

Question

I have the following setting:

import sys 

from flask import Flask
from flask.ext import restful

from model import Model

try:
    gModel = Model(int(sys.argv[1]))
except IndexError, pExc:
    gModel = Model(100)


def main():
    lApp = Flask(__name__)
    lApi = restful.Api(lApp)
    lApi.add_resource(FetchJob, '/')
    lApp.run(debug=True)


class FetchJob(restful.Resource):
    def get(self):
        lRange = gModel.getRange()
        return lRange


if __name__ == '__main__':
    main()

Is there a way to instantiate the Model-class inside the main()-function? Here, the Flask framework instantiates the FetchJob-class, so that I cannot provide it the parameters it forwards during the instantiation process.

I don't like to have global variables as this messes up the whole design ...

Hungarian notation? Please, just no....

ThiefMaster
– ThiefMaster

2013-07-05 18:31:48 +00:00
Commented Jul 5, 2013 at 18:31 — ThiefMaster
– ThiefMaster, Commented Jul 5, 2013 at 18:31

dubbaluga · Accepted Answer · 2013-07-07 09:44:25Z

2

I think this should work, although I'm not familiar with Flask:

import functools

def main():
    try:
        gModel = Model(int(sys.argv[1]))
    except IndexError as pExc:
        gModel = Model(100)
    lApp = Flask(__name__)
    lApi = restful.Api(lApp)
    lApi.add_resource(functools.partial(FetchJob, gModel), '/')
    lApp.run(debug=True)


class FetchJob(restful.Resource):

    def __init__(self, obj, *args, **kwargs):
        restfult.Resource.__init__(self, *args, **kwargs)
        self.obj = obj

    def get(self):
        lRange = self.obj.getRange()
        return lRange

edited Jul 7, 2013 at 9:44

dubbaluga

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answered Jul 5, 2013 at 18:18

Peter Varo

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3 Comments

ThiefMaster Over a year ago

I would use a classmethod on FetchJob for this instead. FetchJob.as_view() which returns a callable.

dubbaluga Over a year ago

Sorry, the functools-version does not work for me. I am getting an AttributeError: 'functools.partial' object has no attribute '__name__' This corresponds to the Python docs: docs.python.org/2/library/functools.html#partial-objects. According to that, partial-objects behave differently compared to "normal" objects.

Peter Varo Over a year ago

If you are looking at the edit history of my post, there was a lambda version as well — everything is the same, but this line is changning: lApi.add_resource(lambda *args, **kwargs: FetchJob(gModel, *args, **kwargs). Try this one out, and let me know if that worked for you.

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