Are nested GraphQL queries with specific id values possible? - graphql

Question

I've successfully built a GraphQL API which allows nested queries. Using the generic examples of Countries & States, I can perform a query like this:
query{
country(id:"Q291bnRyeTo0Nw==") {
states {
edges {
node {
id,
name,
area,
population
}
}
}
}
}
What I've discovered I can't seem to do is this:
query{
country(id:"Q291bnRyeTo0Nw==") {
state(id:"U3RhdGU6MzM=") {
edges {
node {
id,
name,
area,
population
}
}
}
}
}
Might there be a way with GraphQL to specify a specific parent and specific child in one query?
Robert
Update: For Daniel's benefit, here is my current GraphQL Query code:
from .models import Country as CountryModel
from .models import State as StateModel
class Query(graphene.AbstractType):
country = graphene.Field(Country, id=graphene.String())
countries = graphene.List(Country)
state = graphene.Field(State, id=graphene.String())
states = graphene.List(State)
def resolve_country(self, args, context, info):
id = args.get('id')
if id is not None:
return CountryModel.objects.get(id=Schema.decode(id))
return None
def resolve_countries(self, args, context, info):
return CountryModel.objects.all()
def resolve_state(self, args, context, info):
id = args.get('id')
if id is not None:
return StateModel.objects.get(id=Schema.decode(id))
return None
def resolve_states(self, args, context, info):
return StateModel.objects.all()

Answer 1

You'd need to define a resolver for both the country field on the Root Query and the state field on the Country type. Here's an example you can copy and paste into Launchpad and see it in action.
The set up for something like Graphene would be a little different, but the idea is the same: the object returned by your country query is made available to the resolver for every field under the state type. You use the id argument passed to the state field to filter the data on that object (in this example, the returned object has a states property) and return the appropriate state.
import { makeExecutableSchema } from 'graphql-tools';
const countries = [
{
id: 1,
name: 'bar',
states: [
{
name: 'foo',
id: 20
}
]
},
{ id: 2 },
];
const typeDefs = `
type Query {
country(id: Int!): Country
}
type Country {
id: Int
state(id: Int!): State
}
type State {
id: Int
name: String
}
`
const resolvers = {
Query: {
country: (obj, args, context) => {
return countries.find(country => country.id === args.id)
},
},
Country: {
state: (obj, args, context) => {
return obj.states.find(state => state.id === args.id)
},
}
}
export const schema = makeExecutableSchema({
typeDefs,
resolvers,
})
Edit: Assuming the object returned by CountryModel.objects.get(id=Schema.decode(id)) includes a states attribute that is a list of states, you should be able to do something like:
class Country(graphene.ObjectType):
state = graphene.Field(State,
id=graphene.String()
)
# other fields
def resolve_state(self, args, context, info):
id = args.get('id')
if id is not None:
return list(filter(lambda x: x.id == id, self.states)
return None