mongo_paginate@1.1.1

Problem

Imagine that we need to display a list of uncompleted ToDo’s on a website.

import { MongoClient } from "https://deno.land/x/mongo@v0.31.1/mod.ts";
import type { ObjectId } from "https://deno.land/x/mongo@v0.31.1/mod.ts";

const client = new MongoClient();
await client.connect(/* your connection uri */);

const db = client.database(/* database name */);

interface ToDo {
  readonly _id: ObjectId;
  readonly title: string;
  completed: boolean;
}

const collection = db.collection<ToDo>("todos");
const cursor = collection.find({ completed: false });

for await (const todo of cursor) {
  // ...
}

Obviously, it is unprofitable to search for all ToDo’s:

What if there are an infinite number of them?
What if the user wants to see only the first 10 ToDo’s?

Solution

Why not send portions of found ToDo’s as needed? That’s exactly what this module does.

Usage

Import the paginate function to create a FindCursor.

import { paginate } from "https://deno.land/x/mongo_paginate@1.1.1/mod.ts";

const cursor = paginate({
  collection,
  filter: { completed: false },
  limit: 10,
});

const todos = await cursor.toArray();

If the user wants to see more ToDo’s, include the last one from the previous query.

const lastTodo = todos[todos.length - 1];

const nextCursor = paginate({
  collection,
  filter: { completed: false },
  limit: 10,
  cursor: lastTodo._id,
});

const nextTodos = await nextCursor.toArray();

Features

You can also specify the projection or sort order for a better experience.

import { SortOrder } from "https://deno.land/x/mongo_paginate@1.1.1/mod.ts";

const cursor = paginate({
  collection,
  filter: { completed: false },
  limit: 10,
  projection: { completed: 0 },
  order: SortOrder.DESCENDING,
});

const recentTodos = await cursor.toArray();