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1 """ |
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2 This module collects helper functions and classes that "span" multiple levels |
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3 of MVC. In other words, these functions/classes introduce controlled coupling |
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4 for convenience's sake. |
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5 """ |
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6 |
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7 from django.template import loader |
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8 from django.http import HttpResponse, Http404 |
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9 from django.http import HttpResponseRedirect, HttpResponsePermanentRedirect |
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10 from django.db.models.manager import Manager |
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11 from django.db.models.query import QuerySet |
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12 from django.core import urlresolvers |
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13 |
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14 def render_to_response(*args, **kwargs): |
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15 """ |
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16 Returns a HttpResponse whose content is filled with the result of calling |
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17 django.template.loader.render_to_string() with the passed arguments. |
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18 """ |
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19 httpresponse_kwargs = {'mimetype': kwargs.pop('mimetype', None)} |
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20 return HttpResponse(loader.render_to_string(*args, **kwargs), **httpresponse_kwargs) |
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21 |
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22 def redirect(to, *args, **kwargs): |
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23 """ |
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24 Returns an HttpResponseRedirect to the apropriate URL for the arguments |
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25 passed. |
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26 |
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27 The arguments could be: |
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28 |
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29 * A model: the model's `get_absolute_url()` function will be called. |
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30 |
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31 * A view name, possibly with arguments: `urlresolvers.reverse()` will |
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32 be used to reverse-resolve the name. |
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33 |
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34 * A URL, which will be used as-is for the redirect location. |
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35 |
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36 By default issues a temporary redirect; pass permanent=True to issue a |
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37 permanent redirect |
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38 """ |
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39 if kwargs.pop('permanent', False): |
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40 redirect_class = HttpResponsePermanentRedirect |
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41 else: |
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42 redirect_class = HttpResponseRedirect |
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43 |
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44 # If it's a model, use get_absolute_url() |
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45 if hasattr(to, 'get_absolute_url'): |
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46 return redirect_class(to.get_absolute_url()) |
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47 |
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48 # Next try a reverse URL resolution. |
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49 try: |
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50 return redirect_class(urlresolvers.reverse(to, args=args, kwargs=kwargs)) |
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51 except urlresolvers.NoReverseMatch: |
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52 # If this is a callable, re-raise. |
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53 if callable(to): |
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54 raise |
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55 # If this doesn't "feel" like a URL, re-raise. |
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56 if '/' not in to and '.' not in to: |
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57 raise |
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58 |
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59 # Finally, fall back and assume it's a URL |
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60 return redirect_class(to) |
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61 |
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62 def _get_queryset(klass): |
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63 """ |
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64 Returns a QuerySet from a Model, Manager, or QuerySet. Created to make |
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65 get_object_or_404 and get_list_or_404 more DRY. |
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66 """ |
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67 if isinstance(klass, QuerySet): |
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68 return klass |
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69 elif isinstance(klass, Manager): |
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70 manager = klass |
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71 else: |
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72 manager = klass._default_manager |
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73 return manager.all() |
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74 |
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75 def get_object_or_404(klass, *args, **kwargs): |
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76 """ |
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77 Uses get() to return an object, or raises a Http404 exception if the object |
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78 does not exist. |
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79 |
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80 klass may be a Model, Manager, or QuerySet object. All other passed |
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81 arguments and keyword arguments are used in the get() query. |
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82 |
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83 Note: Like with get(), an MultipleObjectsReturned will be raised if more than one |
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84 object is found. |
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85 """ |
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86 queryset = _get_queryset(klass) |
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87 try: |
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88 return queryset.get(*args, **kwargs) |
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89 except queryset.model.DoesNotExist: |
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90 raise Http404('No %s matches the given query.' % queryset.model._meta.object_name) |
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91 |
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92 def get_list_or_404(klass, *args, **kwargs): |
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93 """ |
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94 Uses filter() to return a list of objects, or raise a Http404 exception if |
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95 the list is empty. |
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96 |
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97 klass may be a Model, Manager, or QuerySet object. All other passed |
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98 arguments and keyword arguments are used in the filter() query. |
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99 """ |
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100 queryset = _get_queryset(klass) |
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101 obj_list = list(queryset.filter(*args, **kwargs)) |
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102 if not obj_list: |
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103 raise Http404('No %s matches the given query.' % queryset.model._meta.object_name) |
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104 return obj_list |