GraphQL mutation structure - graphql

Question

I am trying to create a Node.js graphql server in Typescript. I am using Express and express-graphql. I have some issues with how to structure my mutation when I want to create a new User.
My goal is to be able to use a mutation like this:
mutation {
user {
create(
data: {
name: "Foo Bar"
}
) {
id,
name
}
}
}
Here is my User types:
import {
GraphQLObjectType,
GraphQLNonNull,
GraphQLBoolean,
GraphQLString,
GraphQLInputObjectType
} from 'graphql';
export const UserType = new GraphQLObjectType({
name: 'User',
description: 'A user of the application',
fields: () => ({
id: {
type: new GraphQLNonNull(GraphQLString),
description: 'The id of the user',
},
name: {
type: new GraphQLNonNull(GraphQLString),
description: 'The name of the user',
}
})
});
export const UserInputType = new GraphQLInputObjectType({
name: 'UserInputType',
description: 'User payload definition',
fields: () => ({
name: { type: new GraphQLNonNull(GraphQLString) }
})
});
Here is my attempt at defining the mutation on the server:
// ../user/user-mutations.ts
export const userMutations = {
user: {
type: new GraphQLObjectType({
name: 'CreateUser',
fields: {
create: {
type: UserType,
args: {
data: {
type: new GraphQLNonNull(UserInputType),
}
},
resolve: async (rootValue, { data }) => {
return Object.assign(data, {
id: '123'
});
}
}
}
})
}
};
My errors/output:
{
"errors": [
{
"message": "Cannot convert undefined or null to object",
"locations": [
{
"line": 36,
"column": 3
}
],
"path": [
"user"
]
}
],
"data": {
"user": null
}
}
Question 1: Is this way of structuring a mutation not optimal? Should I rather do something like:
mutation {
createUser(
name: "Foo Bar"
) {
id,
name
}
}
Question 2: If my first structure is fine, how can I fix the structure of my mutation on the server to create my user and return the values requested?
Edit: Here is my top level schema:
import { userQueries } from '../user/user-queries';
export const queries = {
...userQueries
};
import { userMutations } from '../user/user-mutations';
export const mutations = {
...userMutations
};
const rootQuery = new GraphQLObjectType({
name: 'RootQuery',
fields: queries
});
const rootMutation = new GraphQLObjectType({
name: 'RootMutation',
fields: mutations
});
export const schema = new GraphQLSchema({
query: rootQuery,
mutation: rootMutation
});