# Prisma Pagination Extension

## Introduction

Prisma Client extension for pagination.

> **Note**
> [Breaking change in `0.5.0`](https://github.com/deptyped/prisma-extension-pagination/releases/tag/v0.5.0)

## Features

- [Page number pagination](#page-number-pagination)
- [Cursor-based pagination](#cursor-based-pagination)
- Fully tested

## Installation

```bash
npm i prisma-extension-pagination
```

### Install extension to all models

```ts
import { PrismaClient } from "@prisma/client";
import { pagination } from "prisma-extension-pagination";

const prisma = new PrismaClient().$extends(pagination());
```

### Install extension on some models

```ts
import { PrismaClient } from "@prisma/client";
import { paginate } from "prisma-extension-pagination";

const prisma = new PrismaClient().$extends({
  model: {
    user: {
      paginate,
    },
  },
});
```

### Change default settings

```ts
import { PrismaClient } from "@prisma/client";
import { pagination } from "prisma-extension-pagination";

const prisma = new PrismaClient().$extends(
  pagination({
    pages: {
      limit: 10, // set default limit to 10
      includePageCount: true, // include counters by default
    },
    cursor: {
      limit: 10, // set default limit to 10

      // set default cursor serialization/deserialization
      getCursor(user: UserType) {
        // ...
      },
      parseCursor(cursor) {
        // ...
      },
    },
  })
);
```

When using the extension on some models, you need to use `createPaginator` function to set the default values:

```ts
import { PrismaClient } from "@prisma/client";
import { createPaginator } from "prisma-extension-pagination";

const paginate = createPaginator({
  // available settings are the same as above
  pages: {
    // ...
  },
  cursor: {
    //...
  },
});

// You can create many paginators with different settings.
// They can be reused for different models.

const prisma = new PrismaClient().$extends({
  model: {
    user: {
      paginate,
    },
    post: {
      paginate,
    },
  },
});
```

## Usage

### Page number pagination

Page number pagination uses `limit` to select a limited range and `page` to load a specific page of results.

- [Load first page](#load-first-page)
- [Load specific page](#load-specific-page)
- [Calculate page count](#calculate-page-count)

#### Load first page

```ts
const [users, meta] = await prisma.user
  .paginate({
    select: {
      id: true,
    }
  })
  .withPages({
    limit: 10,
  });

// meta contains the following
{
  currentPage: 1,
  isFirstPage: true,
  isLastPage: false,
  previousPage: null,
  nextPage: 2,
}
```

#### Load specific page

```ts
const [users, meta] = await prisma.user
  .paginate()
  .withPages({
    limit: 10,
    page: 2,
  });

// meta contains the following
{
  currentPage: 2,
  isFirstPage: false,
  isLastPage: false,
  previousPage: 1,
  nextPage: 3,
}
```

#### Calculate page count

```ts
const [users, meta] = await prisma.user
  .paginate()
  .withPages({
    limit: 10,
    page: 2,
    includePageCount: true,
  });

// meta contains the following
{
  currentPage: 2,
  isFirstPage: false,
  isLastPage: false,
  previousPage: 1,
  nextPage: 3,
  pageCount: 10, // the number of pages is calculated
  totalCount: 100, // the total number of results is calculated
}
```

### Cursor-based pagination

Cursor-based pagination uses `limit` to select a limited range
and `before` or `after` to return a set of results before or after a given cursor.

- [Load first records](#load-first-records)
- [Load next page](#load-next-page)
- [Load previous page](#load-previous-page)
- [Custom cursor serialization](#custom-cursor-serialization)
- [Load all results](#load-all-results)

#### Load first records

```ts
const [users, meta] = await prisma.user
  .paginate({
    select: {
      id: true,
    }
  })
  .withCursor({
    limit: 10,
  });

// meta contains the following
{
  hasPreviousPage: false,
  hasNextPage: true,
  startCursor: "1",
  endCursor: "10"
}
```

#### Load next page

```ts
const [users, meta] = await prisma.user
  .paginate()
  .withCursor({
    limit: 10,
    after: "10"
  });

// meta contains the following
{
  hasPreviousPage: true,
  hasNextPage: true,
  startCursor: "11",
  endCursor: "20"
}
```

#### Load previous page

```ts
const [users, meta] = await prisma.user
  .paginate()
  .withCursor({
    limit: 10,
    before: "11"
  });

// meta contains the following
{
  hasPreviousPage: false,
  hasNextPage: true,
  startCursor: "1",
  endCursor: "10"
}
```

#### Custom cursor serialization

```ts
const getCustomCursor = (postId: number, userId: number) =>
  [postId, userId].join(":");

const parseCustomCursor = (cursor: string) =>
  cursor.split(":");

const [results, meta] = await prisma.postOnUser
  .paginate({
    select: {
      postId: true,
      userId: true,
    },
  })
  .withCursor({
    limit: 10,
    after: getCustomCursor(1, 1), // "1:1"

    // custom cursor serialization
    getCursor({ postId, userId }) {
      return getCustomCursor(postId, userId)
    },

    // custom cursor deserialization
    parseCursor(cursor) {
      const [postId, userId] = parseCustomCursor(cursor);

      return {
        userId_postId: {
          postId: parseInt(postId),
          userId: parseInt(userId),
        },
      };
    },
  });

// meta contains the following
{
  hasPreviousPage: false,
  hasNextPage: true,
  startCursor: "1:2",
  endCursor: "1:11"
}
```

### Load all results

Sometimes it's useful to return all results, if you need to do that, you can pass `limit: null`.

## License

This project is licensed under the terms of the MIT license.