CODEWITHSUNDEEP
pythonclasswsgi
Ericson Willians
Ericson Willians

Reputation: 7855

Why I don't need to pass the required 2 positional arguments in WSGI-compliant apps?

Here's my class:

class App(object):

    def __init__(self, environ, start_response):
        self.environ = environ
        self.start_response = start_response    
        self.html = \
        b"""
            <html>
                <head>
                    <title>Example App</title>
                </head>
                <body>
                    <h1>Example App is working!</h1>
                </body>
            </html>
        """

    def __call__(self):
        self.start_response("200 OK", [("Content-type", "text/html"),
                                        ('Content-Length', str(len(self.html)))])

        return [self.html]

And then I run it:

app = App()

I get a Type Error (obviously) in the Apache error log:

TypeError: __init__() missing 2 required positional arguments: 'environ' and 'start_response'\r

The problem is that every example I saw, they just don't pass those arguments... This one for example:

class Hello(object):

    def __call__(self, environ, start_response):
        start_response('200 OK', [('Content-type','text/plain')])
        return ['Hello World!']

hello = Hello() # ?????????????

How am I supposed to pass those arguments and avoid the Type Error, if every example omit them?

Upvotes: 1

Views: 8697

Answers (1)

Chad S.
Chad S.

Reputation: 6631

You have misread the api doc. Your __init__ method can take any parameters you want (in your App example you probably don't want anything other than self). Then your __call__ method is the one that needs to have the environ and start_response parameters, and you don't call __call__ directly, the WSGI server does.

Something like this is what you want..

class App(object):

    def __init__(self, name):
        self.name = name   
        self.html = \
        b"""
            <html>
                <head>
                    <title>{name}</title>
                </head>
                <body>
                    <h1>{name} is working!</h1>
                </body>
            </html>
        """.format(name=self.name)

    def __call__(self, environ, start_response):
        start_response("200 OK", [("Content-type", "text/html"),
                                  ('Content-Length', str(len(self.html)))])

        return [self.html]

app = App('Example App')

Upvotes: 3

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