GraphQLFieldConfig prevents arguments from being typed

[migueloller]

Using a non-optional type for field arguments is not possible with current TypeScript typings. Here's a small reproduction:

import {
  GraphQLNonNull,
  GraphQLObjectType,
  GraphQLSchema,
  GraphQLString,
} from "graphql";

const queryType = new GraphQLObjectType({
  name: "Query",
  fields: {
    hello: {
      type: new GraphQLNonNull(GraphQLString),
      args: { message: { type: new GraphQLNonNull(GraphQLString) } },
      resolve(rootValue, args: { message: string }) {
        return `Hello, ${args.message}!`;
      },
    },
  },
});

export const schema = new GraphQLSchema({ query: queryType });

src/schema.ts:14:7 - error TS2322: Type '(rootValue: any, args: { message: string; }) => string' is not assignable to type 'GraphQLFieldResolver<any, any, { [argName: string]: any; }>'.
  Types of parameters 'args' and 'args' are incompatible.
    Property 'message' is missing in type '{ [argName: string]: any; }' but required in type '{ message: string; }'.

14       resolve(rootValue, args: { message: string }) {
         ~~~~~~~

  src/schema.ts:14:34
    14       resolve(rootValue, args: { message: string }) {
                                        ~~~~~~~
    'message' is declared here.
  node_modules/graphql/type/definition.d.ts:519:3
    519   resolve?: GraphQLFieldResolver<TSource, TContext, TArgs>;
          ~~~~~~~
    The expected type comes from property 'resolve' which is declared here on type 'GraphQLFieldConfig<any, any, { [argName: string]: any; }>'


Found 1 error.

If the type of args is changed to { message?: string } the problem goes away. But this isn't the correct type since that input field is non-null.

[mabn]

This was broken in #2488