graphql - Apollo GraphQL 服务器中的突变调用有什么问题？

Question

来电：

mutation {
  upvotePost(postId: 1) {
    id
  }
}

响应：

代码下方：

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}`);
});

标签： graphqlapollomutation

Answer 1

为了使用“查找”方法，您需要导入 lodash

npm install lodash

然后在你的文件中需要像这样的lodash：

const { find, filter } = require('lodash');