ganeti_web/views/generic.py

   1 # Copyright (c) 2012 Oregon State University
   2
   3 # Generic class-based view mixins and helpers.
   4
   5 from django.conf import settings
   6 from django.contrib.auth.decorators import login_required
   7 from django.core.exceptions import ImproperlyConfigured
   8 from django.utils.decorators import method_decorator
   9 from django.utils.http import urlencode
  10 from django.utils.translation import ugettext as _
  11
  12 # Standard translation messages. We use these everywhere.
  13
  14 NO_PRIVS = _('You do not have sufficient privileges')
  15
  16
  17 class LoginRequiredMixin(object):
  18     """
  19     Helper mixin which applies @login_required to all methods on a view.
  20
  21     Meant to massively simplify the four-line prelude common to many of our
  22     views.
  23     """
  24
  25     @method_decorator(login_required)
  26     def dispatch(self, *args, **kwargs):
  27         return super(LoginRequiredMixin, self).dispatch(*args, **kwargs)
  28
  29
  30 class PaginationMixin(object):
  31     """
  32     Helper which automatically applies uniform pagination options to any
  33     paginated ListView.
  34     """
  35
  36     paginate_by = settings.ITEMS_PER_PAGE  # list view
  37     table_pagination = {"per_page": settings.ITEMS_PER_PAGE}  # table view
  38
  39     def get_paginate_by(self, queryset):
  40         """
  41         Return the number of items to paginate by.
  42
  43         I like the wording on the other docstring: "An integer specifying how
  44         many objects should be displayed per page."
  45         """
  46
  47         return self.request.GET.get("count", self.paginate_by)
  48
  49
  50 class SortingMixin(object):
  51     """
  52     A mixin which provides sorting for a ListView
  53     """
  54
  55     default_sort_params = None
  56
  57     def get_context_data(self, **kwargs):
  58         context = super(SortingMixin, self).get_context_data(**kwargs)
  59         sort_by, order = self.get_sort_params()
  60         params = {'sort_by': sort_by, 'order': order}
  61         # Store the sort querystring for the current page for easy reuse in
  62         # templates
  63         sort_query = urlencode(params)
  64         params.update({'sort_query': sort_query})
  65         context.update(params)
  66         return context
  67
  68     def get_default_sort_params(self):
  69         if self.default_sort_params is None:
  70             raise ImproperlyConfigured(
  71                 "'SortMixin' requires the 'default_sort_params' "
  72                 "attribute to be set."
  73             )
  74         return self.default_sort_params
  75
  76     def get_sort_params(self):
  77         default_sort_by, default_order = self.get_default_sort_params()
  78         sort_by = self.request.GET.get('sort_by', default_sort_by)
  79         order = self.request.GET.get('order', default_order)
  80         return (sort_by, order)
  81
  82     def get_queryset(self):
  83         return self.sort_queryset(
  84             super(SortingMixin, self).get_queryset(),
  85             *self.get_sort_params())
  86
  87     def sort_queryset(self, qs, sort_by, order):
  88         """
  89         This method is how to specify sorting in your view. By default it
  90         implements a very basic sorting which will use 'sort_by' as the field
  91         to sort, and 'order' as the sorting order.
  92
  93         This is the main function to override and modify for sorting. Any sort
  94         params passed in the url will be passed into this method for use.
  95         """
  96         qs = qs.order_by(sort_by)
  97         if order == 'desc':
  98             qs = qs.reverse()
  99         return qs
 100
 101
 102 class GWMBaseView(object):
 103     """
 104     A base view which will filter querysets by cluster, primary node, or
 105     secondary node. It will also saves these to context data.
 106
 107     This base already includes our standard mixins and if a more custom view is
 108     necessary, the methods can be overloaded.
 109     """
 110     def get_kwargs(self):
 111         """
 112         Get common URL kwargs and assign as object variables.
 113
 114         This is a useful utility method that should be used if you don't want
 115         to call super() on you queryset method at the beginning.
 116         """
 117         self.cluster_slug = self.kwargs.get("cluster_slug", None)
 118         self.pnode = self.kwargs.get("primary_node", None)
 119         self.snode = self.kwargs.get("secondary_node", None)
 120
 121     def get_queryset(self):
 122         self.get_kwargs()  # Make sure that we have our values.
 123         qs = super(GWMBaseView, self).get_queryset()
 124         # Filter by cluster if applicable
 125         if self.cluster_slug:
 126             qs = qs.filter(cluster__slug=self.cluster_slug)
 127
 128         # filter the vms by primary node if applicable
 129         if self.pnode:
 130             qs = qs.filter(primary_node=self.pnode)
 131
 132         # filter the vms by the secondary node if applicable
 133         if self.snode:
 134             qs = qs.filter(secondary_node=self.snode)
 135
 136         return qs
 137
 138     def get_context_data(self, **kwargs):
 139         self.get_kwargs()
 140         context = super(GWMBaseView, self).get_context_data(**kwargs)
 141         context['cluster_slug'] = self.cluster_slug
 142
 143         return context
 144
 145     def can_create(self, cluster):
 146         """
 147         Given an instance of a cluster or all clusters returns
 148         whether or not the logged in user is able to create a VM.
 149         """
 150         user = self.request.user
 151         return (user.is_superuser or user.has_any_perms(cluster,
 152                 ["admin", "create_vm"]))