I am trying to build the search for a Django site I am building, and in that search, I am searching in three different models. And to get pagination on the search result list, I would like to use a generic object_list view to display the results. But to do that, I have to merge three querysets into one.
How can I do that? I've tried this:
result_list = []
page_list = Page.objects.filter(
Q(title__icontains=cleaned_search_term) |
Q(body__icontains=cleaned_search_term))
article_list = Article.objects.filter(
Q(title__icontains=cleaned_search_term) |
Q(body__icontains=cleaned_search_term) |
Q(tags__icontains=cleaned_search_term))
post_list = Post.objects.filter(
Q(title__icontains=cleaned_search_term) |
Q(body__icontains=cleaned_search_term) |
Q(tags__icontains=cleaned_search_term))
for x in page_list:
result_list.append(x)
for x in article_list:
result_list.append(x)
for x in post_list:
result_list.append(x)
return object_list(
request,
queryset=result_list,
template_object_name='result',
paginate_by=10,
extra_context={
'search_term': search_term},
template_name="search/result_list.html")
But this doesn't work. I get an error when I try to use that list in the generic view. The list is missing the clone attribute.
How can I merge the three lists, page_list
, article_list
and post_list
?
Best Answer
Concatenating the querysets into a list is the simplest approach. If the database will be hit for all querysets anyway (e.g. because the result needs to be sorted), this won't add further cost.
Using
itertools.chain
is faster than looping each list and appending elements one by one, sinceitertools
is implemented in C. It also consumes less memory than converting each queryset into a list before concatenating.Now it's possible to sort the resulting list e.g. by date (as requested in hasen j's comment to another answer). The
sorted()
function conveniently accepts a generator and returns a list:If you're using Python 2.4 or later, you can use
attrgetter
instead of a lambda. I remember reading about it being faster, but I didn't see a noticeable speed difference for a million item list.