Feb 22, 2019 · Updated: Jul 12, 2021 · by Tim Kamanin
I'm building a backend for a scraping tool that has two simple models
Website can have many pages.
In a simplified form it looks like:
class Website(models.Model): url = models.URLField(unique=True) class Page(models.Model): website = models.ForeignKey( "Website", on_delete=models.CASCADE, related_name="pages" ) url = models.URLField(max_length=2083) title = models.CharField(max_length=255) content = models.TextField()
And I have an admin panel set in
admin.py like this:
from django.contrib.admin import ModelAdmin class WebsiteAdmin(AdminViews): actions = [scrape_website] list_display = ["url"] search_fields = ["url"]
Now what I want to do is to add a filter to the right-hand sidebar. It will allow me to filter websites by a scraped/not scraped status. And I take that "scraped" means a website has at least one page in the DB and "not scraped" means websites without any pages saved in the database.
And this is where we need to create a custom filter for Django admin. Like many things with Django, it's ridiculously simple, follow my hands:
from django.contrib.admin import ModelAdmin, SimpleListFilter class ScrapeStatusFilter(SimpleListFilter): title = "Scrape status" # a label for our filter parameter_name = "pages" # you can put anything here def lookups(self, request, model_admin): # This is where you create filter options; we have two: return [ ("scraped", "Scraped"), ("not_scraped", "Not scraped"), ] def queryset(self, request, queryset): # This is where you process parameters selected by use via filter options: if self.value() == "scraped": # Get websites that have at least one page. return queryset.distinct().filter(pages__isnull=False) if self.value(): # Get websites that don't have any pages. return queryset.distinct().filter(pages__isnull=True)
The last step is to add
class WebsiteAdmin(AdminViews): actions = [scrape_website] list_display = ["url"] search_fields = ["url"] list_filter = (ScrapeStatusFilter,)
And that should be it. You can now filter a list of websites via the custom crafted filter.
Hey, if you've found this useful, please share the post to help other folks find it: