knex-relay-cursor-pagination

Knex Relay Cursor Pagination

Easy Relay cursor pagination for your Knex queries

• 🚀 implements the GraphQL Cursor Connections Specification
• 🔌 integrates easily with GraphQL tools like Apollo Server
• 📦 zero dependencies, well-tested with 100% coverage

Install

yarn add knex-relay-cursor-pagination

Usage

import { createPagination } from 'knex-relay-cursor-pagination';

export type Post = {
  id: string;
  title: string;
  creation_timestamp: string;
};

async function getPosts(first?: number, after?: string, last?: number, before?: string): Promise<Page<Post>> {
  const pagination = createPagination({
    from: 'posts',
    sortColumn: 'creation_timestamp',
    sortDirection: 'desc',
    cursorColumn: 'id',
    first,
    after,
    last,
    before,
  });

  const rows = await this.db.from('posts')
    .where(pagination.where.column, pagination.where.comparator, pagination.where.value)
    .orderBy(pagination.orderBy.column, pagination.orderBy.direction)
    .limit(pagination.limit)
    .select('*');

  return pagination.getPage<Post>(rows);
}

Advanced sorting criteria

To sort by a derived sorting column, use Knex .with and pass the query alias to .from.

Here is an example of sorting posts by their count of associated comments:

const cte = db
    .from('posts')
    .select(
      'posts.*',
      db.raw(`concat(count("comments"."id"), ':', "posts".id) as comments_count`)
    )
    .leftJoin('comments', 'posts.id', 'comments.post_id')
    .groupBy('posts.id')
    .orderBy('comments_count', 'desc');

const pagination = createPagination({
  from: 'cte',
  sortColumn: 'comments_count',
  sortDirection: 'desc',
  cursorColumn: 'id',
  first,
  after,
  last,
  before,
});

const rows = await db
  .with('cte', cte)
  .from('cte')
  .where(
    pagination.where.column,
    pagination.where.comparator,
    pagination.where.value
  )
  .orderBy(pagination.orderBy.column, pagination.orderBy.direction)
  .limit(pagination.limit);

pagination.getPage<Post>(rows);

API

createPagination(params: PaginationParams)

Takes a configuration parameter and returns an object containing values to pass into the knex query and a function to transform the queried rows into a Relay connection page object.

Configuration parameters

Dataset configuration:

Required

• cursorColumn: the column to be used for the cursor. Values must be unique
• sortColumn: the column that the data is sorted by. Values must be unique
• sortDirection: the sort direction of the data
• from: the table or common-table-expression being queried from

Page slice configuration

Either first or last is required

• first: corresponds to the first param of the Relay spec
• after: corresponds to the after param of the Relay spec
• last: corresponds to the last param of the Relay spec
• before: corresponds to the before param of the Relay spec

Optional configuration

• obfuscateCursor: a function for transforming the cursor's raw value to an opaque value
• deobfuscateCursor: a function for transforming the cursor's opaque value to the raw value
• onCursorMissing: 'omit' | 'throw', the behavior for when a queried row's cursor value is missing. Defaults to 'omit'

Examples

See the example app in the /example directory of this repo. See its README.md for more info.