how to set many-to-many relation in graphql mutation?

问题

I may be missing something, but can not find any information on Apollo docs about the way to set a many-to-many relation when creating a new entry.

When the relation is one-to-many it is as simple as setting the ID of the one-side of the relationship in the many-side object.

But let's pretend I am working with Books and Authors, how would I write a graphql query that creates a Book for one (or many?) Authors?

回答1:

This should probably happen at the API layer on the GraphQL server (i.e. schema). For many-to-many relationships, you should have a "join" type to denote the BookAuthor many-to-many relationship, and then add an entry to that join type.

Essentially then you'll have a type called Book, another called Author, and finally one more called BookAuthor. And you can add a few mutations to be able to manage that relationship. Perhaps...

• addToBookAuthorConnection
• updateBookAuthorConnection
• removeFromBookAuthorConnection

This is a conventional setup using a Relay-spec compliant API. You can read more about how to structure your API for many-to-many relationships here.

Then, you only need to call the addToBookAuthorConnection mutation from Apollo instead to be able to add to that many-to-many connection on your frontend.

Hope this helps!

回答2:

If u r using apollo graph server with one to many relations then connectors.js, resolvers.js and schema.js files as given formats

schema.js

const typeDefinitions = `



type Author {

  authorId: Int
  firstName: String
  lastName: String
  posts: [Post]

}

type Post {

  postId: Int
  title: String 
  text: String
  views: Int
  author: Author

}

input postInput{
  title: String 
  text: String
  views: Int
}


type Query {

  author(firstName: String, lastName: String): [Author]
  posts(postId: Int, title: String, text: String, views: Int): [Post]

}



type Mutation {

createAuthor(firstName: String, lastName: String, posts:[postInput]): Author

updateAuthor(authorId: Int, firstName: String, lastName: String, posts:[postInput]): String

}


schema {
  query: Query
  mutation:Mutation
}
`;

export default [typeDefinitions];

resolvers.js

import { Author } from './connectors';
import { Post } from './connectors';


const resolvers = {

  Query: {
    author(_, args) {
      return Author.findAll({ where: args });
    },
    posts(_, args) {
      return Post.findAll({ where: args });
    }
  },

  Mutation: {

    createAuthor(_, args) {
      console.log(args)
      return Author.create(args, {
        include: [{
          model: Post,
        }]
      });
    },

    updateAuthor(_, args) {

      var updateProfile = { title: "name here" };
      console.log(args.authorId)
      var filter = {
        where: {
          authorId: args.authorId
        },
        include: [
          { model: Post }
        ]
      };
      Author.findOne(filter).then(function (product) {
        Author.update(args, { where: { authorId: args.authorId } }).then(function (result) {
          product.posts[0].updateAttributes(args.posts[0]).then(function (result) {
            //return result;
          })
        });
      })
      return "updated";
    },

  },


  Author: {
    posts(author) {
      return author.getPosts();
    },
  },
  Post: {
    author(post) {
      return post.getAuthor();
    },
  },
};

export default resolvers;

connectors.js

import rp from 'request-promise';
var Sequelize = require('sequelize');
var db = new Sequelize('test', 'postgres', 'postgres', {
  host: '192.168.1.168',
  dialect: 'postgres',

  pool: {
    max: 5,
    min: 0,
    idle: 10000
  }

});


const AuthorModel = db.define('author', {
  authorId: { type: Sequelize.INTEGER, primaryKey: true, autoIncrement: true, field: "author_id" },
  firstName: { type: Sequelize.STRING, field: "first_name" },
  lastName: { type: Sequelize.STRING, field: "last_name" },
},{
        freezeTableName: false,
        timestamps: false,
        underscored: false,
        tableName: "author"
    });


const PostModel = db.define('post', {
    postId: { type: Sequelize.INTEGER, primaryKey: true, autoIncrement: true, field: "post_id" },
  text: { type: Sequelize.STRING },
  title:  { type: Sequelize.STRING },
  views: { type: Sequelize.INTEGER },
},{
        freezeTableName: false,
        timestamps: false,
        underscored: false,
        tableName: "post"
    });


AuthorModel.hasMany(PostModel, {
    foreignKey: 'author_id'
});
PostModel.belongsTo(AuthorModel, {
    foreignKey: 'author_id'
});

const Author = db.models.author;
const Post = db.models.post;

export { Author, Post };

来源：https://stackoverflow.com/questions/43892343/how-to-set-many-to-many-relation-in-graphql-mutation