We Keep Coding

How to add new field to filtered query

I'm trying to add a new column for which I need to do some operations based on other models in a FilterSet.
I have my view like this:
class FilteredListView(ListView):
filterset_class = None
def get_queryset(self):
queryset = super().get_queryset()
self.filterset = self.filterset_class(self.request.GET, queryset=queryset)
return self.filterset.qs.distinct()
def get_context_data(self, **kwargs):
context = super().get_context_data(**kwargs)
context['filterset'] = self.filterset
querysetPaises = Pais.objects.all().filter(paisActivo=1).order_by('nombrePais')
context['paises']=querysetPaises
return context
class ListadoPartnerView(FilteredListView):
filterset_class = PartnerFilter
paginate_by = 10
model = IngresosPersonas
fields = ['idPlataforma', 'number_plataforma', 'contactoinfo']
template_name = 'usuarios/listadoPartners.html'
And my filter is:
class PartnerFilter(django_filters.FilterSet):
class Meta:
model = IngresosPersonas
fields = ['idPlataforma', 'number_plataforma']
Basically I want to include a new column on the filterset that the template receives which is not included in the model.
I've tried to access the filterset.qs but no luck
Many thanks

You can add non model field to FilterSet but you need manually specify method which will be triggered by this filter:
class PartnerFilter(django_filters.FilterSet):
new_field = django_filters.CharFilter(method="filter_new_field")
class Meta:
model = IngresosPersonas
fields = ['idPlataforma', 'number_plataforma', 'new_field']
def filter_new_field(self, queryset, name, value):
return queryset.filter() # your extra filters here
If you need to add non model field on representation level (template) you can just define property in your model:
class MyMode(models.Model):
#property
def new_field(self):
return "some value"
In template you can access this field like this {{ obj.new_field }}.

Django - selectively query models using pk_url_kwarg

Consider the these two models and view:
models.py
class BHA_List(models.Model):
well = models.ForeignKey(WellInfo, 'CASCADE', related_name='bha_list')
bha_number = models.CharField(max_length=100)
class BHA_overall(models.Model):
bha_number = models.ForeignKey(BHA_List, 'CASCADE', related_name='bha_overall')
drill_str_name = models.CharField(max_length=111)
depth_in = models.CharField(max_length=111)
views.py
class BHA_UpdateView(UpdateView):
model = BHA_overall
pk_url_kwarg = 'pk_alt'
form_class = BHA_overall_Form
To my understanding, pk_url_kwarg = 'pk_alt' will query and return instances of model = BHA_overall.
Let's say that I use a different CBV other than UpdateView, and want to implement two models. So something like this:
model = (BHA_overall, BHA_List). Is there any way that I force my pk_url_kwarg = 'pk_alt' to query and return instances only in BHA_List, but force my get_object() return objects in BHA_overall?? What CBV should I use?

you can use just 'View' and define methods post and get.
about like this:
class SomeView(View):
model = BHA_List
template_name = 'some.html'
def get(request, **kwargs):
overall = BHA_overall.objects.all()
return render(request,
self.template_name,
locals())
def get(request, **kwargs):
return render(request, self.template_name, {})

Django limit the choices of a many to many relationship

I know the title says the question has been asked before but the situation is different.
I have something called Agent:
class Agent(models.Model):
user = models.ForeignKey(settings.AUTH_USER_MODEL, related_name='agents')
...
and a Group:
class Group(models.Model):
agents = models.ManyToManyField('agents.Agent', blank=True, related_name='groups')
now with Django class based views (UpdateView maybe) I want create a view that a user can see only its agents and select only one of them to add it to a specific group.
as far as I get was this
#method_decorator(login_required, name='dispatch')
class GroupAgentRegister(UpdateView):
model = Group
fields = ('agents',)
template_name = 'register.html'
context_object_name = 'group'
def get_form(self, form_class=None):
form = super(GroupAgentRegister, self).get_form(form_class)
form.fields['agents'].queryset = self.request.user.agents.all()
return form
def form_valid(self, form):
if self.object.agents.filter(user=self.request.user):
form.add_error(None, ValidationError(u'Already Registered'))
return super(GroupAgentRegister, self).form_invalid(form)
return super(GroupAgentRegister, self).form_valid(form)
the form rendering is fine except that I'm able to select multiple agents.
but when I select a value and post it it replace the new selected agents with existing ones and it's not appended to the old ones.

I solved it this way. it may help others too.
first I created a form:
class GroupRegistrationForm(forms.ModelForm):
agents = forms.ModelChoiceField(Group.objects.none())
class Meta:
model = Group
fields = ('agents',)
and I changed the register view to this:
#method_decorator(login_required, name='dispatch')
class GroupAgentRegister(UpdateView):
model = Group
form_class = GroupRegistrationForm
fields = ('agents',)
template_name = 'register.html'
context_object_name = 'group'
def get_form(self, form_class=None):
form = super(GroupAgentRegister, self).get_form(form_class)
form.fields['agents'].queryset = self.request.user.agents.all()
return form
def form_valid(self, form):
if self.object.agents.filter(user=self.request.user):
form.add_error(None, ValidationError(u'Already Registered'))
return super(GroupAgentRegister, self).form_invalid(form)
self.object.agents.add(form.cleaned_data['agents'])
self.object.save()
return HttpResponseRedirect(self.get_success_url())
and everything works fine with the most minimal change I had to apply.

How can I return regular response in override get method, Django

I try to use class based views in Django. And I have such problem: I define a base class for a blog (BlogBaseView) and two other classes, that inherit it.
And in the second class(BlogIndexView) I want to make the search by get request, so I have override get method. It works, but if I don't make get request, it returns HttpResponse, however I want to return usual context (which BlogIndexView retunes without override get method).
What can I do?
class BlogBaseView(View):
def get_context_data(self, **kwargs):
context = super(BlogBaseView, self).get_context_data(**kwargs)
blog_categories = []
categories = BlogCategory.objects.all()
for category in categories:
blog_categories.append(tuple([category, category.get_number_of_category_items]))
context['name_page'] = 'blog'
context['tags'] = Tag.objects.all()
context['blog_categories'] = blog_categories
return context
class BlogIndexView(BlogBaseView, ListView):
queryset = Post.objects.all().order_by('-date_create')
template_name = 'index_blog.html'
context_object_name = 'posts'
def get(self, request):
if request.GET.get('tag'):
context = {
'posts' : Post.objects.filter(tags__name__in=[request.GET.get('tag')])
}
return render(request, self.template_name, context)
return HttpResponse('result')
class BlogFullPostView(BlogBaseView, DetailView):
model = Post
template_name = 'full_post.html'
pk_url_kwarg = 'post_id'
context_object_name = 'post'
Thanks!

ListView class also has a get_context_data method, so you should override that instead of get method. Using super you'll get access to BlogBaseView.get_context_data and then you can extended the result.
Here's how:
class BlogIndexView(BlogBaseView, ListView):
queryset = Post.objects.all().order_by('-date_create')
template_name = 'index_blog.html'
context_object_name = 'posts'
def get_context_data(self, **kwargs):
# use the (super) force Luke
context = super(BlogIndexView, self).get_context_data(**kwargs)
if self.request.GET.get('tag'):
context['posts'] = Post.objects.filter(tags__name__in=[self.request.GET.get('tag')])
return context

If you are overriding ListView then it's not a good idea to override the get method, as you will lose a lot of the ListView functionality.
In this case, it would be a better idea to override get_queryset, and do the search there.
def get_queryset(self):
queryset = super(BlogIndexView, self). get_queryset()
if request.GET.get('tag'):
queryset = queryset.filter(tags__name=request.GET['tag'])
return queryset

Add user specific fields to Django REST Framework serializer

I want to add a field to a serializer that contains information specific to the user making the current request (I don't want to create a separate endpoint for this). Here is the way I did it:
The viewset:
class ArticleViewSet(viewsets.ModelViewSet):
queryset = Article.objects.all()
serializer_class = ArticleSerializer
filter_class = ArticleFilterSet
def prefetch_likes(self, ids):
self.current_user_likes = dict([(like.article_id, like.pk) for like in Like.objects.filter(user=self.request.user, article_id__in=ids)])
def get_object(self, queryset=None):
article = super(ArticleViewSet, self).get_object(queryset)
self.prefetch_likes([article.pk])
return article
def paginate_queryset(self, queryset, page_size=None):
page = super(ArticleViewSet, self).paginate_queryset(queryset, page_size)
if page is None:
return None
ids = [article.pk for article in page.object_list]
self.prefetch_likes(ids)
return page
The serializer:
class ArticleSerializer(serializers.ModelSerializer):
class Meta:
model = Article
def to_native(self, obj):
ret = super(ArticleSerializer, self).to_native(obj)
if obj:
view = self.context['view']
ret['has_liked'] = False
if hasattr(view, 'current_user_liked'):
ret['has_liked'] = obj.pk in view.current_user_liked
return ret
Is there a better place to inject the prefetching of liked articles, or a nicer way to do this in general?

you can do it with SerializerMethodField
Example :
class PostSerializer(serializers.ModelSerializer):
fav = serializers.SerializerMethodField('likedByUser')
def likedByUser(self, obj):
request = self.context.get('request', None)
if request is not None:
try:
liked=Favorite.objects.filter(user=request.user, post=obj.id).count()
return liked == 1
except Favorite.DoesNotExist:
return False
return "error"
class Meta:
model = Post
then you should call serializer from view like this:
class PostView(APIVIEW):
def get(self,request):
serializers = PostSerializer(PostObjects,context={'request':request})

I'd be inclined to try and put as much of this as possible on the Like model object and then bung the rest in a custom serializer field.
In serializer fields you can access the request via the context parameter that they inherit from their parent serializer.
So you might do something like this:
class LikedByUserField(Field):
def to_native(self, article):
request = self.context.get('request', None)
return Like.user_likes_article(request.user, article)
The user_likes_article class method could then encapsulate your prefetching (and caching) logic.
I hope that helps.

According to the Django Documentation - SerializerMethodField, I had to change the code of rapid2share slightly.
class ResourceSerializer(serializers.ModelSerializer):
liked_by_user = serializers.SerializerMethodField()
def get_liked_by_user(self, obj : Resource):
request = self.context.get('request')
return request is not None and obj.likes.filter(user=request.user).exists()