relay-pagination

# Relay Pagination

Master Relay's cursor-based pagination for efficiently loading and displaying
large datasets with infinite scroll and load more patterns.

## Overview

Relay implements the GraphQL Cursor Connections Specification for efficient
pagination. It provides hooks like usePaginationFragment for declarative
pagination with automatic cache updates and connection management.

## Installation and Setup

### Pagination Query Structure

```graphql
# schema.graphql
type Query {
  posts(
    first: Int
    after: String
    last: Int
    before: String
  ): PostConnection!
}

type PostConnection {
  edges: [PostEdge!]!
  pageInfo: PageInfo!
  totalCount: Int
}

type PostEdge {
  cursor: String!
  node: Post!
}

type PageInfo {
  hasNextPage: Boolean!
  hasPreviousPage: Boolean!
  startCursor: String
  endCursor: String
}

type Post {
  id: ID!
  title: String!
  body: String!
}
```

## Core Patterns

### 1. Basic Pagination

```javascript
// PostsList.jsx
import { graphql, usePaginationFragment } from 'react-relay';

const PostsListFragment = graphql`
  fragment PostsList_query on Query
  @refetchable(queryName: "PostsListPaginationQuery")
  @argumentDefinitions(
    first: { type: "Int", defaultValue: 10 }
    after: { type: "String" }
  ) {
    posts(first: $first, after: $after)
    @connection(key: "PostsList_posts") {
      edges {
        node {
          id
          ...PostCard_post
        }
      }
      pageInfo {
        hasNextPage
        endCursor
      }
    }
  }
`;

function PostsList({ query }) {
  const {
    data,
    loadNext,
    loadPrevious,
    hasNext,
    hasPrevious,
    isLoadingNext,
    isLoadingPrevious,
    refetch
  } = usePaginationFragment(PostsListFragment, query);

  return (
    <div>
      <button
        onClick={() => refetch({ first: 10 })}
        disabled={isLoadingNext}
      >
        Refresh
      </button>

      {data.posts.edges.map(({ node }) => (
        <PostCard key={node.id} post={node} />
      ))}