In UNIX way, each view should solve single task. This is good idea, but sometimes we need to mix logic of different views on same page. Filter, sort, paginate, or, for example, add comment on product page. In this article I'll show how we can mix such multiple views.
Idea
We can write views as decorators.
Example
Simplified filtration can look like this:
from django.views.generic.list_detail import object_list
def filtered_list(request, filterset_class, queryset, *args, **kwargs):
filterset = filterset_class(request.GET)
queryset = filterset.filter(queryset)
kwargs['extra_context']['filterset'] = filterset
return object_list(request, queryset, *args, **kwargs)This is simple and straightforward, but in order to add some tricky pagination, we have to copy entire view and add more code to it.
Instead, we can create decorator like this:
def filtered(view):
def wrapped(request, filterset_class, queryset, *args, **kwargs):
filterset = filterset_class(request.GET)
queryset = filterset.filter(queryset)
kwargs['extra_context']['filterset'] = filterset
return view(request, queryset, *args, **kwargs)
return wrappedResult
Assuming, that we have similar decorators, sorted и paginated, we can easily combine them:
@filtered
@paginated
def technic_list(*args, **kwargs):
# ...Or even like this, in lisp style:
url(r'^technic/$', filtered(sorted(paginated(object_list))), {
'filterset_class': FilterSet,
# ...
}, name='technic_list'),Subscribe for the news and updates
Web development has undergone significant changes over the past five years due to a combination of technological advancements and changing user needs. Let's look at the drivers of these changes and the key technologies that have played a decisive role.
Earlier in our previous article "Improve efficiency of your SELECT queries" we discussed ways to profile and optimize the performance of SELECT queries. However, to write complex yet efficient SQL queries, there is a thing to remember about.
In this article we will write a small library for pulling metadata and creating a preview for a site just like Slack does.
In this article, we will compare two most popular JS Libraries (Angular vs React). Both of them were created by professionals and have been used in famous big projects.
Learn how to use "OR" and "AND" queries efficiently in Django without using database models Q. Enhance your query-building skills. Dive in now.
It appears that not everyone knows that in python you can create classes dynamically without metaclasses. I'll show an example of how to do it.So we've learned how to use custom QuerySet to chain requests:Article.objects.old().public()Now we need to make it work for related objects:user.articles.old().public()This is done using use_for_related_fields, but it needs a little trick.