graphql-relay-connection

A GraphQL Relay connection with custom cursor functions. Can be used for MongoDB, Mongoose, plain objects, scalars, or any data formats.

Install

npm install --save graphql-relay-connection

Usage

mongooseConnection is predefined for you. For other usage, scroll down to Custom connection section below.

1import {
2  connectionDefinitions,
3  connectionArgs,
4} from 'graphql-relay';
5
6import {mongooseConnection} from 'graphql-relay-connection';
7
8const {
9  connectionFromPromisedArray,
10  cursorToDocument,
11} = mongooseConnection;
12
13const UserType = new GraphQLObjectType({
14  name: 'User',
15  fields: () => ({
16    friends: {
17      type: UserConnection,
18      args: connectionArgs,
19      resolve: (user, args) => {
20        args.first = args.first || 10;
21        const doc = cursorToDocument(args.after);
22        const friends = User.find({
23            isFriendWith: user._id,
24            _id: {$gt: doc && doc._id},
25          })
26          .limit(args.first + 1) // add +1 for hasNextPage
27          .exec()
28        return connectionFromPromisedArray(friends, args);
29      },
30    },
31  }),
32});
33
34const {
35  connectionType: UserConnection,
36} = connectionDefinitions({
37  nodeType: UserType,
38});

Custom connection

Simply provide { comparableToCursor, cursorToComparable, comparator } to defineConnection.

1import defineConnection from 'graphql-relay-connection';
2import {
3  base64,
4  unbase64,
5} from './util';
6
7const PREFIX = 'number:';
8
9// Given a comparable value, return a string cursor.
10function numberToCursor(num) {
11  return base64(PREFIX + num);
12}
13
14// Given a string cursor,
15// return a comparable value for the comparator function.
16function cursorToNumber(cursor) {
17  const num = parseInt(unbase64(cursor).substring(PREFIX.length), 10);
18  return isNaN(num) ? null : num;
19}
20
21// Sort function for array.sort().
22// Given two values, return an interger.
23function compareNumbers(num1, num2) {
24  return num1 - num2;
25}
26
27const {
28  connectionFromArray,
29  connectionFromPromisedArray,
30} = defineConnection({
31  comparableToCursor: numberToCursor,
32  cursorToComparable: cursorToNumber,
33  comparator: compareNumbers,
34});

How mongoose connection is defined

1import type {
2  ConnectionCursor,
3} from './connectionTypes';
4import defineConnection from './defineConnection';
5import {
6  base64,
7  unbase64,
8  startsWith,
9} from './util';
10
11
12export type ID = string;
13
14export type Document = {
15  id: ID,
16};
17
18
19const PREFIX = 'mongoose:';
20
21
22function documentToCursor(doc: Document): ConnectionCursor {
23  return base64(PREFIX + doc.id);
24}
25
26
27function cursorToDocument(cursor: ConnectionCursor): ?Document {
28  const unbased = unbase64(cursor);
29  if (startsWith(unbased, PREFIX)) {
30    const id = unbased.substring(PREFIX.length);
31    if (id) return {id};
32  }
33  return null;
34}
35
36
37function compareDocuments(doc1: Document, doc2: Document): number {
38  if (doc1.id < doc2.id) {
39    return -1;
40  }
41  if (doc1.id > doc2.id) {
42    return 1;
43  }
44  return 0;
45}
46
47
48const {
49  connectionFromArray,
50  connectionFromPromisedArray,
51} = defineConnection({
52  comparableToCursor: documentToCursor,
53  cursorToComparable: cursorToDocument,
54  comparator: compareDocuments,
55});
56
57
58export {
59  compareDocuments,
60  connectionFromArray,
61  connectionFromPromisedArray,
62  cursorToDocument,
63  documentToCursor,
64};

License

The MIT License (MIT)

Copyright (c) 2016 Joon Ho Cho

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.