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MongoDB and Mongoose work out of the box with Bun. This guide assumes you’ve already installed MongoDB and are running it as background process/service on your development machine. Follow this guide for details.
Once MongoDB is running, create a directory and initialize it with bun init.
terminal
mkdir mongoose-app
cd mongoose-app
bun init
Then add Mongoose as a dependency.
terminal
bun add mongoose
In schema.ts we’ll declare and export an Animal model.
https://mintcdn.com/bun-1dd33a4e/JUhaF6Mf68z_zHyy/icons/typescript.svg?fit=max&auto=format&n=JUhaF6Mf68z_zHyy&q=85&s=7ac549adaea8d5487d8fbd58cc3ea35bschema.ts
import * as mongoose from "mongoose";

const animalSchema = new mongoose.Schema(
  {
    title: { type: String, required: true },
    sound: { type: String, required: true },
  },
  {
    methods: {
      speak() {
        console.log(`${this.sound}!`);
      },
    },
  },
);

export type Animal = mongoose.InferSchemaType<typeof animalSchema>;
export const Animal = mongoose.model("Animal", animalSchema);
Now from index.ts we can import Animal, connect to MongoDB, and add some data to our database.
https://mintcdn.com/bun-1dd33a4e/JUhaF6Mf68z_zHyy/icons/typescript.svg?fit=max&auto=format&n=JUhaF6Mf68z_zHyy&q=85&s=7ac549adaea8d5487d8fbd58cc3ea35bindex.ts
import * as mongoose from "mongoose";
import { Animal } from "./schema";

// connect to database
await mongoose.connect("mongodb://127.0.0.1:27017/mongoose-app");

// create new Animal
const cow = new Animal({
  title: "Cow",
  sound: "Moo",
});
await cow.save(); // saves to the database

// read all Animals
const animals = await Animal.find();
animals[0].speak(); // logs "Moo!"

// disconnect
await mongoose.disconnect();
Let’s run this with bun run.
terminal
bun run index.ts

Moo!
This is an introduction to using Mongoose with TypeScript and Bun. As you build your application, refer to the official MongoDB and Mongoose sites for complete documentation.