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Filtering
You already can list all links, but another feature of Hackernews is to search them, by URL or description. In GraphQL, this concept is the same as mutations: you pass an argument to the links field, used by the resolver to filter the results.
Filtering Links
Change your links query class to the following:
.../graphql-python/hackernews/links/schema.py
# ..code
# After the imports, add
from django.db.models import Q
# ...code
class Query(graphene.ObjectType):
# Add the search parameter inside our links field
links = graphene.List(LinkType, search=graphene.String())
votes = graphene.List(VoteType)
# Change the resolver
def resolve_links(self, info, search=None, **kwargs):
# The value sent with the search parameter will be in the args variable
if search:
filter = (
Q(url__icontains=search) |
Q(description__icontains=search)
)
return Link.objects.filter(filter)
return Link.objects.all()
def resolve_votes(self, info, **kwargs):
return Vote.objects.all()
To test it, just pass the search argument to the query:
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What would happen if you ran the last query without the search parameter?
The application would break
The search parameter is mandatory
All the Links would be returned
Just the first Link would be returned
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