[Node.js] GraphQLで更新する

var schema = buildSchema(`
	type Query {
		course(id: Int!): Course
		courses(topic: String):[Course]
	},
	type Mutation {
		updateCourseTopic(id: Int!, topic: String!): Course
	}
	type Course {
		id: Int
		title: String
		author: String
		description: String
		topic: String
		url: String
	}
`);

// 省略

var updateCourseTopic = function({id, topic}){
	coursesData.map(course => {
		if(course.id === id){
			course.topic = topic;
			return course;
		}
	});
	return coursesData.filter(course => course.id === id)[0];
}
var root = {
	course: getCourse,
	courses: getCourses,
	updateCourseTopic: updateCourseTopic
};

$ node server2.js

mutation updateCourseTopic($id: Int!, $topic: String!) {
  updateCourseTopic(id: $id, topic: $topic) {
    ... courseFields 
  }
}
fragment courseFields on Course {
 title
 author
 description
 topic
 url
}

{
 "id": 1,
 "topic": "JavaScript"
}

何となく使い方はわかりました。