def connection_from_cursor_paginated(queryset,
connection_type,
edge_type,
pageinfo_type,
page_query=None):
"""Create a Connection object from a queryset, using CursorPaginator"""
paginator = CursorPaginator(queryset, queryset.query.order_by)
if page_query is None:
page_query = PageQuery()
page = paginator.page(**attr.asdict(page_query))
edges = []
for item in list(page):
edge = edge_type(node=item, cursor=paginator.cursor(item))
edges.append(edge)
if page:
page_info = pageinfo_type(
start_cursor=paginator.cursor(edges[0].node),
end_cursor=paginator.cursor(edges[-1].node),
has_previous_page=page.has_previous,
has_next_page=page.has_next,
)
else:
page_info = pageinfo_type(
start_cursor=None,
end_cursor=None,
has_previous_page=False,
has_next_page=False,
)
return connection_type(
edges=edges,
page_info=page_info,
)
def test_reverse_order(self):
paginator = CursorPaginator(Post.objects.all(), ('-created', '-name'))
previous_page = paginator.page(first=2)
self.assertSequenceEqual(previous_page, [self.items[3], self.items[2]])
cursor = paginator.cursor(previous_page[-1])
page = paginator.page(first=2, after=cursor)
self.assertSequenceEqual(page, [self.items[1], self.items[0]])
def search(user_id, search_term, before=None, after=None):
"""Offload the expensive part of search to avoid blocking the web interface"""
if not search_term:
return {
"results": [],
"has_next": False
}
if before and after:
raise ValueError("You can't do this.")
email_subquery = models.Email.objects.viewable(user_id)
inbox_subquery = models.Inbox.objects.viewable(user_id)
search_qs = watson_search.search(search_term, models=(email_subquery, inbox_subquery))
page_kwargs = {
"after": after,
"before": before,
}
if before:
page_kwargs["last"] = SEARCH_PAGE_SIZE
else:
page_kwargs["first"] = SEARCH_PAGE_SIZE
paginator = CursorPaginator(search_qs, ordering=('-watson_rank', '-id'))
page = paginator.page(**page_kwargs)
results = {
"results": [p.id for p in page],
"has_next": page.has_next,
"has_previous": page.has_previous,
}
if len(results["results"]) > 0:
results["last"] = paginator.cursor(page[-1])
results["first"] = paginator.cursor(page[0])
key = create_search_cache_key(user_id, search_term, before, after)
cache.set(key, results, SEARCH_TIMEOUT)
return results
def chunked_queryset_iterator(queryset, size, *, ordering=('id', )):
pager = CursorPaginator(queryset, ordering)
after = None
while True:
page = pager.page(after=after, first=size)
if page:
yield from page.items
else:
return
if not page.has_next:
break
after = pager.cursor(instance=page[-1])
def ApiListView(request):
params = request.GET
queryset = Video.objects.all().order_by('-published_at')
page_size = 10
paginator = CursorPaginator(queryset, ordering=['-id'])
if 'before' in params:
before = params['before']
page = paginator.page(first=page_size, before=before)
elif 'after' in params:
after = params['after']
page = paginator.page(first=page_size, after=after)
else:
page = paginator.page(first=page_size, after=None)
data = {
'objects': [VideoSerializer(p).data for p in page],
'has_next_page': page.has_next,
'has_previous_page': page.has_previous,
'last_cursor': paginator.cursor(page[-1]),
'first_cursor': paginator.cursor(page[0])
}
return JsonResponse(data)
def search(user_id, search_term, before=None, after=None):
"""Offload the expensive part of search to avoid blocking the web interface"""
if not search_term:
return {"results": [], "has_next": False}
if before and after:
raise ValueError("You can't do this.")
email_subquery = models.Email.objects.viewable(user_id)
inbox_subquery = models.Inbox.objects.viewable(user_id)
search_qs = watson_search.search(search_term,
models=(email_subquery, inbox_subquery))
page_kwargs = {
"after": after,
"before": before,
}
if before:
page_kwargs["last"] = SEARCH_PAGE_SIZE
else:
page_kwargs["first"] = SEARCH_PAGE_SIZE
paginator = CursorPaginator(search_qs, ordering=('-watson_rank', '-id'))
page = paginator.page(**page_kwargs)
results = {
"results": [p.id for p in page],
"has_next": page.has_next,
"has_previous": page.has_previous,
}
if len(results["results"]) > 0:
results["last"] = paginator.cursor(page[-1])
results["first"] = paginator.cursor(page[0])
key = create_search_cache_key(user_id, search_term, before, after)
cache.set(key, results, SEARCH_TIMEOUT)
return results
def _chunked_queryset_iterator(queryset, size, *, ordering=('id', )):
"""
Split a queryset into chunks.
This can be used instead of `queryset.iterator()`,
so `.prefetch_related()` also works
Note::
The ordering must uniquely identify the object,
and be in the same order (ASC/DESC). See https://github.com/photocrowd/django-cursor-pagination
"""
pager = CursorPaginator(queryset, ordering)
after = None
while True:
page = pager.page(after=after, first=size)
if page:
yield from page.items
else:
return
if not page.has_next:
break
# take last item, next page starts after this.
after = pager.cursor(instance=page[-1])
