What is wrong with mutation call in Apollo GraphQL server? - graphql

Question

The call:
mutation {
upvotePost(postId: 1) {
id
}
}
The response:
Below the code:
const { ApolloServer, gql } = require('apollo-server');
const typeDefs = `
type Author {
id: Int!
firstName: String
lastName: String
"""
the list of Posts by this author
"""
posts: [Post]
}
type Post {
id: Int!
title: String
author: Author
votes: Int
}
# the schema allows the following query:
type Query {
posts: [Post]
author(id: Int!): Author
}
# this schema allows the following mutation:
type Mutation {
upvotePost (
postId: Int!
): Post
}
`;
// example data
const authors = [
{ id: 1, firstName: 'Tom', lastName: 'Coleman' },
{ id: 2, firstName: 'Sashko', lastName: 'Stubailo' },
{ id: 3, firstName: 'Mikhail', lastName: 'Novikov' },
];
const posts = [
{ id: 1, authorId: 1, title: 'Introduction to GraphQL', votes: 2 },
{ id: 2, authorId: 2, title: 'Welcome to Meteor', votes: 3 },
{ id: 3, authorId: 2, title: 'Advanced GraphQL', votes: 1 },
{ id: 4, authorId: 3, title: 'Launchpad is Cool', votes: 7 },
];
const resolvers = {
Query: {
posts: () => posts,
author: (_, { id }) => find(authors, { id }),
},
Mutation: {
upvotePost: (_, { postId }) => {
const post = find(posts, { id: postId });
if (!post) {
throw new Error(`Couldn't find post with id ${postId}`);
}
post.votes += 1;
return post;
},
},
Author: {
posts: author => filter(posts, { authorId: author.id }),
},
Post: {
author: post => find(authors, { id: post.authorId }),
},
};
// The ApolloServer constructor requires two parameters: your schema
// definition and your set of resolvers.
const server = new ApolloServer({ typeDefs, resolvers });
// The `listen` method launches a web server.
server.listen().then(({ url }) => {
console.log(`🚀 Server ready at ${url}`);
});

Answer 1

In order to use the 'find' method you need to import lodash
npm install lodash
Then in your file require lodash like this:
const { find, filter } = require('lodash');