Implement page number pagination (#3)

* Implement page number pagination

* Add docs

.github/workflows/main.yml

@@ -23,4 +23,5 @@ jobs:
       - run: npm ci
       - run: npm run lint
       - run: npx prisma generate && npm run build
-      - run: npm test
+      - run: npx prisma migrate deploy && npm test
+

README.md

@@ -1,25 +1,89 @@
+# Prisma Pagination Extension
+
 ## Introduction
 
-Prisma Client extension template with watch mode and testing.
+Prisma Client extension for pagination.
+
+## Features
 
-## Getting Started
+- [Page number pagination](#page-number-pagination).
 
-### 1. Clone the repository or generate new repository using this template via [link](https://github.com/deptyped/prisma-extension-template/generate)
+## Installation
 
 ```bash
-git clone https://github.com/deptyped/prisma-extension-template
+npm i prisma-extension-pagination
 ```
 
-### 2. Install dependencies
+## Usage
 
-```bash
-npm i
+### Install extension
+
+```ts
+import { PrismaClient } from "@prisma/client";
+import pagination from "prisma-extension-pagination";
+
+const prisma = new PrismaClient().$extends(pagination);
 ```
 
-### 3. Start watch mode
+### Page number pagination
 
-```bash
-npm run dev
+Page number pagination uses `limit` to select a limited range and `page` to load a specific page of results.
+
+#### Load first page
+
+```ts
+const [users, meta] = prisma.user.paginate().withPages({
+  limit: 10
+});
+
+// meta contains the following
+{
+  currentPage: 1,
+  isFirstPage: true,
+  isLastPage: false,
+  previousPage: null,
+  nextPage: 2,
+  pageCount: null,
+}
+```
+
+#### Load specific page
+
+```ts
+const [users, meta] = prisma.user.paginate().withPages({
+  limit: 10,
+  page: 2
+});
+
+// meta contains the following
+{
+  currentPage: 2,
+  isFirstPage: false,
+  isLastPage: false,
+  previousPage: 1,
+  nextPage: 3,
+  pageCount: null,
+}
+```
+
+#### Calculate page count
+
+```ts
+const [users, meta] = 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
+}
 ```
 
 ## License

jest.config.js

@@ -2,4 +2,6 @@
 module.exports = {
   preset: "ts-jest",
   testEnvironment: "node",
+  globalSetup: "<rootDir>/test/bootstrap/setup.ts",
+  globalTeardown: "<rootDir>/test/bootstrap/teardown.ts",
 };

prisma/migrations/20230118181852_initial/migration.sql

@@ -0,0 +1,24 @@
+-- CreateTable
+CREATE TABLE "User" (
+    "id" INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    "name" TEXT
+);
+
+-- CreateTable
+CREATE TABLE "Post" (
+    "id" INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    "title" TEXT
+);
+
+-- CreateTable
+CREATE TABLE "PostOnUser" (
+    "userId" INTEGER NOT NULL,
+    "postId" INTEGER NOT NULL,
+
+    PRIMARY KEY ("userId", "postId"),
+    CONSTRAINT "PostOnUser_userId_fkey" FOREIGN KEY ("userId") REFERENCES "User" ("id") ON DELETE CASCADE ON UPDATE CASCADE,
+    CONSTRAINT "PostOnUser_postId_fkey" FOREIGN KEY ("postId") REFERENCES "Post" ("id") ON DELETE CASCADE ON UPDATE CASCADE
+);
+
+-- CreateIndex
+CREATE UNIQUE INDEX "PostOnUser_userId_postId_key" ON "PostOnUser"("userId", "postId");

prisma/migrations/migration_lock.toml

@@ -0,0 +1,3 @@
+# Please do not edit this file manually
+# It should be added in your version-control system (i.e. Git)
+provider = "sqlite"

prisma/schema.prisma

@@ -1,6 +1,3 @@
-// This is your Prisma schema file,
-// learn more about it in the docs: https://pris.ly/d/prisma-schema
-
 generator client {
   provider = "prisma-client-js"
   previewFeatures = ["clientExtensions"]
@@ -13,24 +10,24 @@ datasource db {
 
 model User {
   id        Int      @id @default(autoincrement())
-  email     String   @unique
   name      String?
-  posts     Post[]
-  profile   Profile?
+  posts     PostOnUser[]
 }
 
 model Post {
   id        Int      @id @default(autoincrement())
-  title     String
-  content   String?
-  published Boolean  @default(false)
-  author    User     @relation(fields: [authorId], references: [id])
-  authorId  Int
+  title      String?
+
+  authors    PostOnUser[]
 }
 
-model Profile {
-  id     Int     @id @default(autoincrement())
-  bio    String?
-  user   User    @relation(fields: [userId], references: [id])
-  userId Int     @unique
+model PostOnUser {
+  userId Int   
+  user   User    @relation(fields: [userId], references: [id], onDelete: Cascade)
+  
+  postId Int   
+  post   Post    @relation(fields: [postId], references: [id], onDelete: Cascade)
+
+  @@id([userId, postId])
+  @@unique([userId, postId])
 }

src/extension.ts

@@ -1,9 +1,141 @@
 import { Prisma } from "@prisma/client";
+import { PageNumberPaginationOptions, PageNumberPaginationMeta } from "./types";
+
+type PrismaModel = {
+  [k in "findMany" | "count"]: CallableFunction;
+};
+
+type PrismaQuery = {
+  where: Record<string, unknown>;
+};
+
+const paginateWithPages = async (
+  model: PrismaModel,
+  query: PrismaQuery,
+  limit: number,
+  currentPage: number
+): Promise<[unknown, PageNumberPaginationMeta]> => {
+  const results = await model.findMany({
+    ...query,
+    ...{
+      skip: (currentPage - 1) * limit,
+      take: limit + 1,
+    },
+  });
+
+  const previousPage = currentPage > 1 ? currentPage - 1 : null;
+  const nextPage = results.length > limit ? currentPage + 1 : null;
+  if (nextPage) {
+    results.pop();
+  }
+
+  return [
+    results,
+    {
+      isFirstPage: previousPage === null,
+      isLastPage: nextPage === null,
+      currentPage,
+      previousPage,
+      nextPage,
+      pageCount: null,
+    },
+  ];
+};
+
+const paginateWithPagesIncludePageCount = async (
+  model: PrismaModel,
+  query: PrismaQuery,
+  limit: number,
+  currentPage: number
+): Promise<[unknown, PageNumberPaginationMeta]> => {
+  const [results, totalCount] = await Promise.all([
+    model.findMany({
+      ...query,
+      ...{
+        skip: (currentPage - 1) * limit,
+        take: limit,
+      },
+    }),
+    model.count({ where: query?.where }),
+  ]);
+
+  const pageCount = Math.ceil(totalCount / limit);
+  const previousPage = currentPage > 1 ? currentPage - 1 : null;
+  const nextPage = currentPage < pageCount ? currentPage + 1 : null;
+
+  return [
+    results,
+    {
+      isFirstPage: previousPage === null,
+      isLastPage: nextPage === null,
+      currentPage,
+      previousPage,
+      nextPage,
+      pageCount,
+    },
+  ];
+};
 
 export const extension = Prisma.defineExtension({
-  client: {
-    $deepThought() {
-      return 42;
+  name: "pagination",
+  model: {
+    $allModels: {
+      paginate<T extends PrismaModel, A>(
+        this: T,
+        args?: Prisma.Exact<
+          A,
+          Omit<Prisma.Args<T, "findMany">, "cursor" | "take" | "skip">
+        >
+      ) {
+        return {
+          withPages: async (
+            options: PageNumberPaginationOptions
+          ): Promise<
+            [Prisma.Result<T, A, "findMany">, PageNumberPaginationMeta]
+          > => {
+            const {
+              page: currentPage,
+              limit,
+              includePageCount,
+            } = {
+              page: 1,
+              includePageCount: false,
+              ...options,
+            } satisfies PageNumberPaginationOptions;
+
+            if (
+              typeof currentPage !== "number" ||
+              currentPage < 1 ||
+              currentPage > Number.MAX_SAFE_INTEGER
+            ) {
+              throw new Error("Invalid page option value");
+            }
+
+            if (
+              typeof limit !== "number" ||
+              limit < 1 ||
+              limit > Number.MAX_SAFE_INTEGER
+            ) {
+              throw new Error("Invalid limit option value");
+            }
+
+            const query = (args ?? {}) as PrismaQuery;
+
+            return (
+              includePageCount
+                ? paginateWithPagesIncludePageCount(
+                    this,
+                    query,
+                    limit,
+                    currentPage
+                  )
+                : paginateWithPages(this, query, limit, currentPage)
+            ) as Promise<
+              [Prisma.Result<T, A, "findMany">, PageNumberPaginationMeta]
+            >;
+          },
+        };
+      },
     },
   },
 });

src/index.ts

@@ -1 +1,2 @@
 export { extension as default } from "./extension";
+export * from "./types";

src/types.ts

@@ -0,0 +1,14 @@
+export type PageNumberPaginationOptions = {
+  limit: number;
+  page?: number;
+  includePageCount?: boolean;
+};
+
+export type PageNumberPaginationMeta = {
+  isFirstPage: boolean;
+  isLastPage: boolean;
+  currentPage: number;
+  previousPage: number | null;
+  nextPage: number | null;
+  pageCount: number | null;
+};

test/bootstrap/setup.ts

@@ -0,0 +1,36 @@
+import { USERS_COUNT } from "../helpers/constants";
+import { prisma } from "../helpers/prisma";
+
+const setup = async () => {
+  await prisma.$connect();
+
+  await Promise.all(
+    [...Array(USERS_COUNT)].map(() =>
+      prisma.user.create({
+        select: {
+          id: true,
+        },
+        data: {
+          posts: {
+            create: [
+              {
+                post: {
+                  create: {},
+                },
+              },
+              {
+                post: {
+                  create: {
+                    title: "Untitled",
+                  },
+                },
+              },
+            ],
+          },
+        },
+      })
+    )
+  );
+};
+
+export default setup;