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Connecting to databases

The Deno community has published a number of third-party modules that make it easy to connect to popular databases like MySQL, Postgres, and MongoDB.

They are hosted at Deno's third-party module site deno.land/x.

MySQL​

deno_mysql is a MySQL and MariaDB database driver for Deno.

Connect to MySQL with deno_mysql​

import { Client } from "https://deno.land/x/mysql/mod.ts";

const client = await new Client().connect({
  hostname: "127.0.0.1",
  username: "root",
  db: "dbname",
  password: "password",
});

Postgres​

deno-postgres is a lightweight PostgreSQL driver for Deno focused on developer experience.

Connect to Postgres with deno-postgres​

import { Client } from "https://deno.land/x/postgres/mod.ts";

const client = new Client({
  user: "user",
  database: "dbname",
  hostname: "127.0.0.1",
  port: 5432,
  password: "password",
});
await client.connect();

postgresjs is a full-featured Postgres client for Node.js and Deno.

Connect to Postgres with postgresjs​

import postgres from "https://deno.land/x/postgresjs/mod.js";

const sql = postgres("postgres://username:password@host:port/database");

MongoDB​

We suggest using npm specifiers to work with the official MongoDB driver on npm. You can learn more about how to work with the driver in the official docs. The only difference using this module in the context of Deno will be how you import the module using an npm: specifier.

Import the MongoDB driver using npm specifiers
// Import the latest major version of the MongoDB driver
import { MongoClient } from "npm:mongodb@6";

// Configure a MongoDB client
const url = "mongodb://localhost:27017";
const client = new MongoClient(url);
const dbName = "myProject";

// Connect to a MongoDB instance
await client.connect();
console.log("Connected successfully to server");

// Get a reference to a collection
const db = client.db(dbName);
const collection = db.collection("documents");

// Execute an insert operation
const insertResult = await collection.insertMany([{ a: 1 }, { a: 2 }]);
console.log("Inserted documents =>", insertResult);

// Close the connection
client.close();

SQLite​

There are two primary solutions to connect to SQLite in Deno:

Connect to SQLite with the FFI Module​

sqlite3 provides JavaScript bindings to the SQLite3 C API, using Deno FFI.

import { Database } from "https://deno.land/x/sqlite3@LATEST_VERSION/mod.ts";

const db = new Database("test.db");

db.close();

Connect to SQLite with the WASM-Optimized Module​

sqlite is a SQLite module for JavaScript and TypeScript. The wrapper made specifically for Deno and uses a version of SQLite3 compiled to WebAssembly (WASM).

import { DB } from "https://deno.land/x/sqlite/mod.ts";

const db = new DB("test.db");

db.close();

Firebase​

To connect to Firebase with Deno, import the firestore npm module with the skypak CDN. To learn more about using npm modules in Deno with a CDN, see Using npm packages with CDNs.

Connect to Firebase with the firestore npm module​

import { initializeApp } from "https://www.gstatic.com/firebasejs/9.8.1/firebase-app.js";

import {
  addDoc,
  collection,
  connectFirestoreEmulator,
  deleteDoc,
  doc,
  Firestore,
  getDoc,
  getDocs,
  getFirestore,
  query,
  QuerySnapshot,
  setDoc,
  where,
} from "https://www.gstatic.com/firebasejs/9.8.1/firebase-firestore.js";

import { getAuth } from "https://www.gstatic.com/firebasejs/9.8.1/firebase-auth.js";

const app = initializeApp({
  apiKey: Deno.env.get("FIREBASE_API_KEY"),
  authDomain: Deno.env.get("FIREBASE_AUTH_DOMAIN"),
  projectId: Deno.env.get("FIREBASE_PROJECT_ID"),
  storageBucket: Deno.env.get("FIREBASE_STORAGE_BUCKET"),
  messagingSenderId: Deno.env.get("FIREBASE_MESSING_SENDER_ID"),
  appId: Deno.env.get("FIREBASE_APP_ID"),
  measurementId: Deno.env.get("FIREBASE_MEASUREMENT_ID"),
});
const db = getFirestore(app);
const auth = getAuth(app);

Supabase​

To connect to Supabase with Deno, import the supabase-js npm module with the esm.sh CDN. To learn more about using npm modules in Deno with a CDN, see Using npm packages with CDNs.

Connect to Supabase with the supabase-js npm module​

import { createClient } from "https://esm.sh/@supabase/supabase-js";

const options = {
  schema: "public",
  headers: { "x-my-custom-header": "my-app-name" },
  autoRefreshToken: true,
  persistSession: true,
  detectSessionInUrl: true,
};

const supabase = createClient(
  "https://xyzcompany.supabase.co",
  "public-anon-key",
  options,
);

ORMs​

Object-Relational Mappings (ORM) define your data models as classes that you can persist to a database. You can read and write data in your database through instances of these classes.

Deno supports multiple ORMs, including Prisma and DenoDB.

DenoDB​

DenoDB is a Deno-specific ORM.

Connect to DenoDB​

import {
  Database,
  DataTypes,
  Model,
  PostgresConnector,
} from "https://deno.land/x/denodb/mod.ts";

const connection = new PostgresConnector({
  host: "...",
  username: "user",
  password: "password",
  database: "airlines",
});

const db = new Database(connection);

GraphQL​

GraphQL is an API query language often used to compose disparate data sources into client-centric APIs. To set up a GraphQL API, you should first set up a GraphQL server. This server exposes your data as a GraphQL API that your client applications can query for data.

Server​

You can use gql, an universal GraphQL HTTP middleware for Deno, to run a GraphQL API server in Deno.

Run a GraphQL API server with gql​

import { GraphQLHTTP } from "https://deno.land/x/gql/mod.ts";
import { makeExecutableSchema } from "https://deno.land/x/graphql_tools@0.0.2/mod.ts";
import { gql } from "https://deno.land/x/graphql_tag@0.0.1/mod.ts";

const typeDefs = gql`
  type Query {
    hello: String
  }
`;

const resolvers = {
  Query: {
    hello: () => `Hello World!`,
  },
};

const schema = makeExecutableSchema({ resolvers, typeDefs });

Deno.serve({ port: 3000 }, async () => {
  const { pathname } = new URL(req.url);

  return pathname === "/graphql"
    ? await GraphQLHTTP<Request>({
      schema,
      graphiql: true,
    })(req)
    : new Response("Not Found", { status: 404 });
});

Client​

To make GraphQL client calls in Deno, import the graphql npm module with the esm CDN. To learn more about using npm modules in Deno via CDN read here.

Make GraphQL client calls with the graphql npm module​

import { buildSchema, graphql } from "https://esm.sh/graphql";

const schema = buildSchema(`
type Query {
  hello: String
}
`);

const rootValue = {
  hello: () => {
    return "Hello world!";
  },
};

const response = await graphql({
  schema,
  source: "{ hello }",
  rootValue,
});

console.log(response);