NewsBlur-viq/utils/view_functions.py

import functools

from django.http import Http404, HttpResponse
from django.shortcuts import render

from utils import json_functions as json


def get_argument_or_404(request, param, method="POST", code="404"):
    try:
        return getattr(request, method)[param]
    except KeyError:
        if code == "404":
            raise Http404
        else:
            return


def render_to(template):
    """
    Decorator for Django views that sends returned dict to render function.

    If view doesn't return dict then decorator simply returns output.
    Additionally view can return two-tuple, which must contain dict as first
    element and string with template name as second. This string will
    override template name, given as parameter

    Parameters:

     - template: template name to use
    """

    def renderer(func):
        def wrapper(request, *args, **kw):
            output = func(request, *args, **kw)
            if isinstance(output, (list, tuple)):
                return render(request, output[1], output[0])
            elif isinstance(output, dict):
                return render(request, template, output)
            return output

        return wrapper

    return renderer


def is_true(value):
    if value == 1:
        return True
    return bool(value) and isinstance(value, str) and value.lower() not in ("false", "0")


class required_params(object):
    "Instances of this class can be used as decorators"

    def __init__(self, *args, **kwargs):
        self.params = args
        self.named_params = kwargs
        self.method = kwargs.get("method", "POST")

    def __call__(self, fn):
        def wrapper(request, *args, **kwargs):
            return self.view_wrapper(request, fn, *args, **kwargs)

        functools.update_wrapper(wrapper, fn)
        return wrapper

    def view_wrapper(self, request, fn, *args, **kwargs):
        if request.method != self.method and self.method != "REQUEST":
            return self.disallowed(method=True, status_code=405)

        # Check if parameter is included
        for param in self.params:
            if getattr(request, self.method).get(param) is None:
                print(" Unnamed parameter not found: %s" % param)
                return self.disallowed(param)

        # Check if parameter is correct type
        for param, param_type in list(self.named_params.items()):
            if param == "method":
                continue
            if getattr(request, self.method).get(param) is None:
                print(" Typed parameter not found: %s" % param)
                return self.disallowed(param)
            try:
                if param_type(getattr(request, self.method).get(param)) is None:
                    print(" Typed parameter wrong: %s" % param)
                    return self.disallowed(param, param_type)
            except (TypeError, ValueError) as e:
                print(" %s -> %s" % (param, e))
                return self.disallowed(param, param_type)

        return fn(request, *args, **kwargs)

    def disallowed(self, param=None, param_type=None, method=False, status_code=400):
        if method:
            message = "Invalid HTTP method. Use %s." % self.method
        elif param_type:
            message = "Invalid paramter: %s - needs to be %s" % (
                param,
                param_type,
            )
        else:
            message = "Missing parameter: %s" % param

        return HttpResponse(
            json.encode(
                {
                    "message": message,
                    "code": -1,
                }
            ),
            content_type="application/json",
            status=status_code,
        )