UsefulDjangoMixins.py

from django.db.models import Q
from django.contrib import messages


class SearchViewMixin:

    """
    this mixins allow a class based view to handle dynamically and automatically
    a search. It add a GET param name as 's' which hold the searched term, and use 
    lookup_fields = [] to perform search
    
    WARNING : At the moment this method fail silenty
              Should be used only with a ListView class
    
    How it work :
    - Let your view inherit from this mixins
    - Add lookup_fields as a method of your class and assign a list of fields you want to perform the search into
    - In your template just add a form  as follow (May be in future i will add this directly into this mixin's code): 
          <form action="{% url 'YOUR_URL_HERE' %}" method='GET'>
            <input type='text' name='s' />
            <input type='submit' value='search' />
          </form>
    - The search result is available directly in your self.context_object_name context var within the template
          
     Example : 
     
     class ArticleListView(SearchViewMixin, ListView):
          lookup_fields = ['ATTRIBUTE_1', 'ATTRIBUTE_2',]
          pass
    """

    _search_term = ''
    _lookup_expression = 'icontains'

    def _is_search(self):
        if 's' in self.request.GET:
            self._search_term = self.request.GET['s']
            return True
        else:
            return False
    
    def is_searchable(self):
        """
        verify if the current model can accept automatic search, following this mixin rules
        """
        return hasattr(self, 'lookup_fields') and type(self.lookup_fields) == list and len(self.lookup_fields) > 0

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        if self._is_search():
            if self.is_searchable():
                lookup = '{}__{}'.format(self.lookup_fields, self._lookup_expression)
                __lookup_dir = {}
                Qr = None
                # build the search query with Q object based on the list of lookup field
                for item in self.lookup_fields:
                    __lookup_dir = {}
                    __lookup_dir[
                        '{}__{}'.format(item, self._lookup_expression)
                    ] = self._search_term
                    q = Q(**__lookup_dir)
                    if Qr:
                        Qr = Qr | q
                    else:
                        Qr = q
                context[self.context_object_name] = self.model.objects.filter(Qr)
        return context

    
class MessageWinErrorMixin:
    """
    Working on a project (even a legacy code) and you want to quickly add default feedback messages
    to all your class based view which handle forms, just add this mixins and you're done !!!
    
    example :
    
      class MyFormClass(FormView, MessageWinErrorMixin):
          pass
          
    """

    def form_valid(self, data):
        messages.success(self.request, 'Operation successful !')
        return super().form_valid(data)

    def form_invalid(self, error):
        messages.error(self.request, 'Sorry !!! An error occur when processing the form. {}'.format(error.errors))
        return super().form_invalid(error)