GraphQL pass args to sub resolve - graphql

Question

I have a relationship between User and Post. This is how I query the User Posts.
const UserType = new GraphQLObjectType({
name: 'User'
fields: () => ({
name: {
type: GraphQLString
},
posts: {
type: new GraphQLList(PostType),
resolve(parent, args , { db }) {
// I want to get here the args.someBooleanArg
return someLogicToGetUserPosts();
}
}
})
});
The main query is:
const queryType = new GraphQLObjectType({
name: 'RootQuery',
fields: {
users: {
type: new GraphQLList(UserType),
args: {
id: {
type: GraphQLInt
},
someBooleanArg: {
type: GraphQLInt
}
},
resolve: (root, { id, someBooleanArg }, { db }) => {
return someLogicToGetUsers();
}
}
}
});
The problem is the args in the resolve function of the UserType posts is empty object, how do i pass the args from the main query to sub resolves functions?

Answer 1

When resolving the root query you can use object assign to attach the argument to the user object returned.
Then, on the user type, resolve the argument from the root value (first argument of resolve function).
Example:
const queryType = new GraphQLObjectType({
name: 'RootQuery',
fields: {
users: {
type: new GraphQLList(UserType),
args: {
id: {
type: GraphQLInt
},
someBooleanArg: {
type: GraphQLInt
}
},
resolve: (root, { id, someBooleanArg }, { db }) => {
return Promise.resolve(someLogicToGetUsers()).then(v => {
return Object.assign({}, v, {
someBooleanArg
});
});
}
}
}
});
const UserType = new GraphQLObjectType({
name: 'User'
fields: () => ({
name: {
type: GraphQLString
},
posts: {
type: new GraphQLList(PostType),
resolve(parent, args , { db }) {
console.log(parent.someBooleanArg);
return someLogicToGetUserPosts();
}
}
})
});

Answer 2

You can use the resolver fouth argument, info, to receive the desired variable - from Apollo docs:
Every resolver in a GraphQL.js schema accepts four positional arguments:
fieldName(obj, args, context, info)
{ result }
These arguments have
the following meanings and conventional names:
obj: The object that contains the result returned from the resolver on
the parent field, or, in the case of a top-level Query field, the
rootValue passed from the server configuration. This argument enables
the nested nature of GraphQL queries.
args: An object with the
arguments passed into the field in the query. For example, if the
field was called with author(name: "Ada"), the args object would be: {
"name": "Ada" }.
context: This is an object shared by all resolvers in
a particular query, and is used to contain per-request state,
including authentication information, dataloader instances, and
anything else that should be taken into account when resolving the
query. If you're using Apollo Server, read about how to set the
context in the setup documentation.
info: This argument should only be
used in advanced cases, but it contains information about the
execution state of the query, including the field name, path to the
field from the root, and more. It's only documented in the GraphQL.js
source code.
The info seems to be a very undocumented feature, but I'm using it now with no problems (at least until somebody decide to change it).
Here is the trick:
const UserType = new GraphQLObjectType({
name: 'User'
fields: () => ({
name: {
type: GraphQLString
},
posts: {
type: new GraphQLList(PostType),
resolve(parent, args , { db }, info) {
// I want to get here the args.someBooleanArg
console.log("BINGO!");
console.log(info.variableValues.someBooleanArg);
return someLogicToGetUserPosts();
}
}
})
});