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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

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

deno_mongo is a MongoDB database driver developed for Deno.

Connect to MongoDB with deno_mongo

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

const client = new MongoClient();

// Connecting to a Local Database
await client.connect("mongodb://127.0.0.1:27017");

// Connecting to a Mongo Atlas Database
await client.connect({
  db: "<db_name>",
  tls: true,
  servers: [
    {
      host: "<db_cluster_url>",
      port: 27017,
    },
  ],
  credential: {
    username: "<username>",
    password: "<password>",
    db: "<db_name>",
    mechanism: "SCRAM-SHA-1",
  },
});

// Connect using srv url
await client.connect(
  "mongodb+srv://<username>:<password>@<db_cluster_url>/<db_name>?authMechanism=SCRAM-SHA-1",
);

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 is targeted at 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 via CDN read here

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 via CDN read here

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

The idea with ORMs (object relational mapping) is to define your data models as classes that can be persisted to a database. The classes and their instances then provide you with a programmatic API to read and write data in the database.

Deno has support for a number of popular ORMs, including Prisma and DenoDB.

DenoDB

Denodb is a Deno-specific ORM database. ORM (object-relational mapping) databases allow instances of classes to be persisted to a database.

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

Server (GQL)

The simplest way to run a GraphQL API server in Deno is to use gql, an universal GraphQL HTTP middleware for Deno.

Run a GraphQL API Server with gql

import { Server } from "https://deno.land/std@0.165.0/http/server.ts";
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 });

const s = new Server({
  handler: async (req) => {
    const { pathname } = new URL(req.url);

    return pathname === "/graphql"
      ? await GraphQLHTTP<Request>({
        schema,
        graphiql: true,
      })(req)
      : new Response("Not Found", { status: 404 });
  },
  port: 3000,
});

s.listenAndServe();

console.log(`Started on http://localhost:3000`);

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);